- Compact style
- Indico style
- Indico style - inline minutes
- Indico style - numbered
- Indico style - numbered + minutes
- Indico Weeks View
Help us make Indico better by taking this survey! Aidez-nous à améliorer Indico en répondant à ce sondage !
Organised by CSSM, the University of Adelaide
Quantum computing is a novel and promising way to solve problems
that are extremely hard or even impossible to address with classical
computers.
We will discuss applications of quantum computing particularly for
high energy and nuclear physics.
This concerns theoretical models from lattice
gauge theories in 1+1- and 2+1-dimensions with the prospect
to eventually reach 3+1-dimensional models, relevant for the standard
model and beyond. We will discuss, how
such models can be formulated for a quantum computation and provide examples
for real hardware simulations including real time phenomena
and sign problem afflicted situations as carried out already today.
Recent progress in hadron-hadron interactions with lattice QCD simulations close to the physical pion mass opens the door for quantitative studies of the poorly understood low-energy hadron interactions with charm and strange quarks. It also allows comparison with femtoscopic studies in pp, pA, and AA collisions at RHIC (Relativistic Heavy Ion Collider at BNL) and LHC (Large Hadron Collider at CERN) as well as with the hypernuclear studies at J-PARC. After an overview of the basic theoretical concepts of the HAL QCD method for extracting hadronic interactions from lattice QCD data, interplay between theoretical and experimental studies will be presented, taking the H-dibaryon (6-quark system with uuddss component) and thetetraquark Tcc (doubly charmed 4-quark system) as examples. Ongoing program of physical point lattice QCD simulations using RIKEN's FUGAKI supercomputer will also be mentioned.
Morning tea
The quark model was formulated in 1964 to classify mesons as bound states made of a quark–antiquark pair, and baryons as bound states made of three quarks. However, in principle QCD also allows the existence of more complex structures, generically called exotic hadrons or known as XYZ states. These include fourquark hadrons (tetraquarks and hadronic molecules), five-quark hadrons (pentaquarks) and states with active gluonic degrees of freedom (hybrids), and even states of pure glue (glueballs). Exotic hadrons have been systematically searched for in numerous experiments for many years. This talk aims at reviewing the rapid progress in the field of exotic XYZ hadrons over the past 20 years in experiments.
After discussing the landscape of strongly interacting field theories, I will introduce novel theoretical approaches aimed at solving their complex dynamics. Following this, I will explore applications to particle and astroparticle physics, including the discovery of new strong dynamics via gravitational wave observatories. In the realm of particle physics, I will provide a mathematical classification of various extensions to the Standard Model based on their degree of naturalness. I will argue for the existence of a dual description of the Standard Model using “electric” variables, inspired by Dirac's electromagnetic duality and gauge-gauge duality in supersymmetric quantum field theories (QFTs).Finally, I will present a toy dual Standard Model to highlight key aspects of duality, offering potential elegant solutions to longstanding problems, such as the existence of three generations and the possibility that the Standard Model is a natural theory hidden in plain sight.
The phase structure of QCD remains an open fundamental problem of standard model physics. In particular at finite density, where importance sampling based methods like lattice QCD are severely restricted, our knowledge is limited. Yet, numerous model studies point towards a rich and complex phase diagram at large density. In addition to their fundamental relevance, the thermodynamic and transport properties of QCD in this regime are crucial for our understanding of the fireball created in heavy-ion collisions, as well as neutrons stars and their mergers. Functional methods like the functional renormalization group and Dyson-Schwinger equations offer a way to study hot and dense QCD matter directly from first principles. I will discuss the phase structure of QCD and its experimental signatures through the lens of these methods.
In collisions of heavy ions at ultra-relativistic energies at the Large Hadron Collider the deconfined state of nuclear matter, dubbed quark-gluon plasma (QGP), is produced.
Measurements of collective anisotropic flow have extensively contributed to the foundation of a perfect liquid paradigm about QGP properties, according to which QGP is the state of matter with the smallest specific shear viscosity ever discovered.
This talk presents new experimental methods and observables for anisotropic flow analyses developed recently, which can further constrain the QGP properties and other stages of nuclear matter produced in heavy-ion collisions. In particular, new multi-harmonic flow observables, Symmetric Cumulants (SC) and Asymmetric Cumulants (AC) of flow amplitudes are introduced, and their advantages over traditional flow observables are discussed. Theoretically, it is demonstrated that only SC and AC observables satisfy all fundamental properties of multivariate cumulants in a strict mathematical sense. Experimentally, it is found that these new flow observables can reveal for the first time the details of the differential temperature dependence of QGP's specific shear viscosity.
The talk concludes by presenting the latest measurements of multi-harmonic flow observables in heavy-ion collisions. A comparison with predictions from state-of-the-art theoretical models is made.
(Anti)deuterons, being the simplest light ions, have recently become the subject of many studies aimed at a better understanding of their production mechanisms in heavy-ion collisions where the quark–gluon plasma is formed. The mystery surrounding (anti)deuterons lies in their small binding energy, which holds the neutron and the proton together. This binding energy is about seventy times smaller than the freeze-out temperature, raising the question of whether they are produced by thermal or coalescence processes. This question has not yet been resolved. Moreover, the study of (anti)deuterons is crucial due to their interactions with other particles, since they consist of two nucleons. Investigating kaon-deuteron pairs opens up possibilities to explore hadron-hadron interactions in the strangeness sector by determining the isospin-dependent parameters of the strong interaction. Analyzing pairs such as proton-deuteron can enhance our understanding of 2- and 3-body interactions. The study of pion-deuteron pairs, in turn, can provide insights into the emission properties of heavier particle species.
In this talk, the femtoscopy study of (anti)deuterons with charged pions, kaons, and (anti)protons is presented. The particle pairs considered in these studies come from Pb--Pb collisions at an energy of $\sqrt{s_{\rm NN}} = 5.02$ TeV, as recorded by the ALICE experiment. All studies compare experimental femtoscopic correlation functions with theoretical ones from available models of the interactions.
The ALICE experiment at the LHC has extensively studied the production of light flavour particles from small to large hadronic collision systems. In particular, ALICE measured the production of rare probes, such as strange and multistrange hadrons, light (anti-)nuclei, such as (anti-)deuterons, (anti-)triton, (anti-)helium, together with their strange counterparts, i.e. (anti-)hyper-nuclei.
Studying strangeness hadronization and (anti)nucleosynthesis in hadronic and heavy-ion collisions is crucial to shed light on differences and similarities between small and large collision systems. In addition, understanding the production mechanisms of these particles has direct applications in cosmic ray physics, particularly for indirect dark matter searches in space.
This talk will present an overview of recent ALICE measurements in the light flavour sector in pp and AA collisions. These measurements address several open points, including the continuous enhancement of strange to non-strange particle production with the event multiplicity observed from small to large collision systems at the LHC and the different production scenarios for light nuclei and hyper-nuclei in hadronic collisions, such as thermal statistical production or coalescence of nucleons. The experimental results will also be compared with predictions from state-of-the-art theoretical models.
Hidden-flavour states are being actively studied at Belle II; the
programme is currently focussed on energy scan data taken above the
Upsilon(4S). Several results will be discussed, including constraints
on the properties of the Upsilon(10753), and analyses combining Belle
and Belle II data. Prospects for further results will also be set out,
including measurements based on the growing Upsilon(4S) dataset.
I will summarise some recent work on charm mesons and charmonium resonances, including exotics, using first-principles lattice QCD calculations. Investigations of S-wave $D\pi$ scattering will be presented, relevant for the $D^{\ast}_0(2300)$ and the enigmatic $D^{\ast}_{s0}(2317)$, where an exotic-flavour virtual bound state was found. Of other results that will be discussed, a highlight is a study of scalar and tensor charmonium resonances where a single $\chi_{c0}$ and a single $\chi_{c2}$ resonance were found in the energy region up to about 4100 MeV. Above the $\chi_{c0}$ ground state, no other scalar bound states or near-$D\bar{D}$ threshold resonances were found, in contrast to a number of theoretical and experimental studies. I will also comment on future prospects.
The XYZ exotic states discovered in the hadronic sector with two heavy quarks constitute one of the most important open problems in particle theory. In this talk, I show that an effective field theory derived from QCD, the Born Oppenheimer effective field theory (BOEFT), can describe exotics of any composition. I show the results of general Schr\"odinger coupled equations for arbitrary angular momentum of the light degrees of freedom. The coupled equations describe hybrids, tetraquarks, pentaquarks, doubly heavy baryons, and quarkonia in leading order, including nonadiabatic terms. Additionally, I also present the results of the predicted multiplets, corresponding selection rules, and expressions of the nonperturbative gauge invariant correlators, which are the input of the BOEFT: static energies, generalized Wilson loops, gluelumps, and adjoint mesons that should be calculated on the lattice. Moreover, based on BOEFT, I show new results on the behavior of tetraquark/pentaquark static energies at short distances and mixing with the threshold at long distances. As an application of this BOEFT. I show results for the hybrid spectrum and decay to quarkonium.
The spectrum of hadronic states holds valuable information about the interaction of the strong force. Photoproduction experiments can provide crucial insights due to their ability to produce a wide range of conventional and non-conventional hadrons, such as exotic hybrid mesons with gluonic degrees of freedom.
The GlueX experiment at Jefferson Lab, VA, USA, features a 9 GeV linearly polarized photon beam, incident on a fixed LH2 target. A hermetic detector system with excellent charged and neutral particle identification capabilities surrounds the interaction region and provides coverage for charged and neutral final states. This makes GlueX well suited to study the light meson and baryon spectrum.
This talk will present recent results from GlueX from our initial campaign of data taking.
We present a new method of using lattice QCD to extract the intrinsic soft function and the Collins-Soper kernel for TMDPDFs. This method relies on the computation of Wilson loops involving Wilson lines with complex directional vectors. In this talk, progress in numerical implementation of this approach will also be discussed.
We review recent developments in the determination of the quark and gluon structure of hadrons from global QCD analysis within the JAM analysis framework, including polarized and unpolarized PDFs in the proton, and momentum distributions in the pion.
We consider the capture of dark matter in neutron stars, and the heating caused by the subsequent thermalization and annihilation of that dark matter. We find that most of the dark matter’s kinetic energy is rapidly deposited in the star. Furthermore, we find that capture-annihilation equilibrium, and hence maximal annihilation heating, can be achieved without complete thermalization of the captured dark matter. Comparing projected neutron star sensitivities with limits from direct detection experiments, we find that neutron stars provide a possible means to probe dark matter interactions that would be difficult or impossible to observe in experiments on Earth.
We investigate QCD at large isospin density by computing correlation functions between sources with isospin charge $n=1,\ldots,6144$ on two lattice volumes at quark masses corresponding to a pion mass, $m_\pi\sim170$ MeV. By extracting the energies of the corresponding many-pion systems under the assumption of log-normality of the correlation function distributions, we determine the isospin chemical potential, the speed of sound, and related thermodynamic properties of the dense medium, extending previous work to considerably higher isospin chemical potentials, $\mu_I$. Significant deviations from perturbative QCD are seen until $\mu_I>10m_\pi$ and the speed of sound is seen to significantly exceed the expectation from a free gas of quarks over a large range of isospin chemical potentials. Implications for the nuclear equation of state at non-zero baryon chemical potential will also be discussed.
Core-Collapse Supernovae, the explosions of massive stars, are among the several types of gravitational-wave sources yet to be discovered by gravitational wave interferometers. These cataclysmic events may yield insights into the nuclear EoS at multiple times nuclear saturation density. I will review the current advancements in deducing properties of the proto-compact star from gravitational wave spectrograms obtained through Core-Collapse Supernova simulations. Specifically, I want to discuss the excitation of an inner g-mode located in the interior of the proto-compact star. The frequency of this mode falls within the decihertz range and is linked to the speed of sound at approximately four times saturation density.
A 22 GeV upgrade to the CEBAF accelerator at Jefferson Lab has been made possible by recent novel advances in accelerator technology. CEBAF’s envisioned capabilities, at the highest luminosities, will enable exciting opportunities to give scientists the full suite of tools necessary to comprehensively understand how QCD builds hadronic matter in the valence region. This talk will focus on the continuing development of the scientific case for the upgrade, with descriptions and concrete projections for experiments that are foreseen.
There is a flavor number range of $SU(3)$ gauge theory, $N_f^* < N_f < 16.5$, where spontaneous chiral symmetry breaking does not occur and the model is conformal. The upper end $16.5$ is determined by the 1-loop $\beta$-function but the lower end $N_f^*$ may be determined by non-perturbative phenomena. In this contribution a new approach is presented to estimate or constrain $N_f^*$: high order perturbative results are presented for meson masses and decay constants valid close to the upper end, $N_f \simeq 16.5$, and these are matched to continuum extrapolated lattice results in the range $2 \leq N_f \leq 10$. An attempt is made to match them in the intermediate range. It appears a significant qualitative change occurs in the studied quantities at around $N_f = 12$.
The Belle II collaboration recently announced that they observed the $B^+ \rightarrow K^+ \nu \bar{\nu}$ decay process for the first time. This mode has been theoretically identified as a very clean channel. However, their result encounters a 2.7 $\sigma$ deviation from the Standard Model (SM) calculation. On the other hand, last year, Fermilab released new data on muon g−2 away from the SM expectation with 5σ. In this letter, we study the simplest UV-complete $U(1)_{𝖫_\mu−𝖫_\tau}$-charged complex scalar Dark Matter (DM) model. Thanks to the existence of light dark Higgs boson and light dark photon, we can explain the observed relic density of DM and resolve the results reported by both Belle II and Fermilab experiments simultaneously. As a byproduct, the Hubble tension is alleviated by taking $\Delta N_{\rm 𝖾𝖿𝖿} \simeq 0.3$ induced by the light dark photon.
We go beyond the state-of-the-art by combining first principal lattice results and effective field theory approaches as Polyakov Loop model to explore the non-perturbative dark deconfinement-confinement phase transition and the generation of gravitational-waves in a dark Yang-Mills theory. We further include fermions with different representations in the dark sector. Employing the Polyakov-Nambu-Jona-Lasinio (PNJL) model, we discover that the relevant gravitational wave signatures are highly dependent on the various representations. We also find a remarkable interplay between the deconfinement-confinement and chiral phase transitions. In both scenarios, the future Big Bang Observer and DECIGO experiment have a higher chance to detect the gravitational wave signals. Most recently, via Quark-Meson model, we find the phase transition and thus gravitational wave signals will be significantly enhanced when the system is near conformal. In addition, we find that this effective field theory approach can be implemented to study the glueball dark matter production mechanism and for the first time provide a solid prediction of glueball dark matter abundance. Our prediction is an order of magnitude smaller than the existing glueball abundance results in the literature.
The gauge/gravity duality, combined with information from lattice QCD, nuclear theory, and perturbative QCD, can be used to constrain the equation of state of hot and dense QCD. I discuss an approach based on the holographic V-QCD model, which includes both nuclear and quark matter phases, separated by a first order phase transition. By using this model in state-of-the-art simulations of neutron star binaries, I study the formation of quark matter during the merger process, and its effect on the threshold mass for prompt collapse into a black hole.
The double copy mechanism relates the scattering amplitudes of Yang-Mills theories to the theory of gravity. In this talk I will demonstrate how gravitational amplitudes in arbitrary dimensions can be obtained via the double copy prescription of gauge theories. I will further demonstrate that the prescription holds even for compactified gauge theories, which can be related to compactified gravitational theories, and present the equivalent strong coupling scales of both theories.
The $SU(3)\otimes SU(2) \otimes U(1)$ standard model maps smoothly
onto a conventional lattice gauge formulation, including the
parity violation of the weak interactions. The formulation makes
use of the pseudo-reality of the weak group and requires the
inclusion a full generation of both leptons and quarks. As in
continuum discussions, chiral eigenstates of the Dirac operator
generate known anomalies, although with rough gauge configurations
these are no longer exact zero modes of the Dirac operator.
I will describe recent work on anomalies and fractional instantons on a twisted four torus and their relevance for the calculation of the gaugino condensate in minimally-supersymmetric four-dimensional Yang Mills theory
The phenomenon of unpaired Weyl fermions appearing on the sole
2𝑛-dimensional boundary of a (2𝑛+1)-dimensional manifold with massive Dirac fermions was recently analyzed. I discuss how similar unpaired Weyl edge states can be seen on a finite lattice. In particular, I consider the discretized Hamiltonian for a Wilson fermion in (2+1) dimensions with a 1+1 dimensional boundary and continuous time. The low lying boundary spectrum is indeed Weyl-like: it has a linear dispersion relation and definite chirality and circulates in only one direction around the boundary. This results is consistent with Nielsen-Ninomiya theorem and removes one potential obstacle facing the program of regulating chiral gauge theories.
In this work, we study the in- and out-of-equilibrium Chiral Magnetic Effects (CME) from lattice QCD simulations using two approaches. In the equilibrium approach, we consider a non-uniform magnetic background and show that local chiral magnetic currents appear as a response. We show that these currents average zero in the full volume, confirming that the total CME conductivity vanishes in equilibrium. This approach is based on the leading-order coefficient of the vector current in a chiral chemical potential expansion, which we extrapolate to the continuum limit. In the out-of-equilibrium approach, we give the first steps towards the extraction of the out-of equilibrium CME conductivity via temporal lattice correlation functions in a uniform magnetic background. We conclude by discussing possible implications of our findings to heavy-ion physics.
The differential photon emissivity of the QGP is proportional to the transverse channel spectral function $\sigma(\omega)$ at lightlike kinematics.
Estimating the full energy-differential photon emissivity of a medium at thermal equilibrium from lattice QCD poses a challenge, as it involves a numerically ill-posed inverse problem. However, energy-integrated information on the photon emissivity can be obtained without confronting an inverse problem utilizing spatially transverse Euclidean correlators $H_E(\omega_n)$ evaluated at imaginary spatial momenta.
Employing two flavors of $\mathcal{O}(a)$-improved Wilson fermions, we have performed measurements with very high statistics using stochastic wall sources. For this study, we are using three ensembles with lattice spacings in the range of $0.033-0.049\,$fm, thus allowing for a continuum extrapolation of the first two energy-moments $\sigma(\omega)/\omega$ at a fixed temperature $T \approx 254\,$MeV.
As the inserted momenta needed for the second energy-moment are of $\mathcal{O}(3\,\text{GeV})$, one faces a severe signal-to-noise problem. In adressing this issue, we have modelled the tail of the integrand with two-state fits and also bound the result from above using a bounding method. This allows for a comparison of the difference $H_E(\omega_2)- H_E(\omega_1)$ to the weak-coupling prediction by Arnold, Moore and Yaffe without the weak-coupling uncertainties associated with the very soft photons.
We extend the recent study of $K_{1}/K^{*}$ enhancement as a signature of chiral symmetry restoration in heavy ion collisions at the Large Hadron Collider (LHC) via the kinetic approach to include the effects due to non-unity hadron fugacities during the evolution of produced hadronic matter and the temperature-dependent $K_1$ mass. Although including non-unity pion and kaon fugacities reduces slightly the $K_1/K^*$ enhancement found in previous study due to chiral symmetry restoration, adding temperature-dependent $K_1$ mass leads to a substantial further reduction of the $K_1/K^*$ enhancement. However, the final $K_1/K^*$ ratio in peripheral collisions still shows a factor of 2.4 enhancement compared to the case without chiral symmetry restoration, confirming its use as a good signature for chiral symmetry restoration in the hot dense matter produced in relativistic heavy ion collisions.
Open heavy flavor and quarkonium observables are well established probes of the hot system produced in heavy-ion collisions. Open heavy flavor production is better under control than quarkonium in $p + p$ collisions due to uncertainties in the production mechanism. Newer observables such as correlated heavy flavor decays and production of exotics such as tetraquarks are generating added excitement. Highlights from $p + p$, $p + A$ and $A + A$ collisions will be shown, with some emphasis on results from the HEFTY collaboration.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and was also supported in part by LLNL LDRD 23-LW-036.
Thermal photon and dilepton rates are central probes for understanding the quark-gluon plasma and QCD at high temperatures. As a consequence there is a strong interest to determine them using lattice QCD calculations. However, this is made difficult as they are related to thermal spectral functions that are not directly accessible through lattice calculations. Instead they are indirectly obtainable through performing an inverse Laplace-type transformation of Euclidean time lattice correlation functions. In this talk we will present recent results in dynamical QCD with a focus on advancements in spectral reconstruction from lattice data.
We study the properties of the hadron-hadron potentials and quark-antiquark potentials from the viewpoint of the channel coupling[1]. We introduce the effective hadron-hadron potential with coupled to the quark channel.
As an application, we construct a coupled-channel model of $c\bar{c}$ and $D\bar{D}$ to describe exotic hadron $X(3872)$[2].
For the obtained nonlocal potentials, we apply two methods of the local approximation proposed previously, the formal derivative expansion and the derivative expansion in the HAL QCD method, by carefully examining the energy dependence of the potential.
We confirm that the local approximation by the HAL QCD method works better than the formal derivative expansion also for the energy-dependent potential. At the same time, we show that, in the HAL QCD method, the resulting phase shift is sensitive to the choice of the wavefunction to construct the local potential when the system has a shallow bound state such as $X(3872)$.
To investigate the internal structure of the $X(3872)$, we introduce the direct 4-point interaction of the hadron channel, in addition to the contribution of the coupling to the quark channel. We study the dominant compornent of the $X(3872)$ by annalyzing the wavefunctions, compositteness, and pole trajectories.
[1] I. Terashima and T. Hyodo, Phys. Rev. C 108, 035204 (2023).
[2] M. Takizawa and S. Takeuchi, PTEP 2013, 093D01 (2013).
In a recent publication [Few Body Syst. 65 (2024) , 59] we derived covariant equations describing the tetraquark in terms of an admixture of two-body states DD ̄ (diquark-antidiquark) and MM (meson-meson), with three-body-like states (where two of the quarks are spectators while the other two are interacting), and qq ̄ annihilation taken into account exactly. These equations have the feature of being exact in that all neglected terms are taken into account in a clear way through the inclusion of a single qq ̄ potential ∆. In addition, it was shown that the two-body t matrix Ta, describing the interaction of particle-pair a, enters the theory in terms of sums T + = Ta + Ta′ and products T× = TaTa′, and that by treating T+ perturbatively, one can unify separate well- established models of tetraquarks. However, the presence of poles (associated with the formation of diquarks and mesons) in the single terms Ta and Ta′ is a disadvantage of such a perturbative expansion. In the present work, by extracting the full information on the single-term poles contained within ∆, we are able to take into account T + in full, at once enabling us to propose a more practical expansion where the pole parts of Ta and Ta′ are treated non-perturbatively.
Recently, exotic hadrons have attracted much attention. Most exotic hadrons appear near the threshold; $X(3872)$ near the $D\bar{D}^{*}$ threshold, $T_{cc}$ near the $DD^{*}$, $P_{c}$ near the $\Sigma_c \bar{D}^{(*)}$. It is important to study the hadron scattering near threshold in order to clarify the nature of exotic hadrons. Based on this observation, we discuss the general behavior of the near-threshold scattering amplitude with channel couplings.
Currently, the Flatte amplitude is often used to analyze the experimental data. However, it is known that some condition is imposed on the Flatte amplitude near the threshold [1]. In this study, we first compare the Flatte amplitude with the Contact amplitude [2] derived from the effective field theory with contact interaction, and clarify the constraint imposed on the Flatte amplitude. Furthermore, we show that the Contact amplitude cannot reduce to the Flatte amplitude directly.
To solve the above problems, we propose the General amplitude [3] that can reduce to both the Contact amplitude and the Flatte amplitude. By using the General amplitude, we find that the cross section may show the dip structures that cannot be reproduced by Flatte amplitude.
[1] V. Baru et al., Eur. Phys. J. A 23, 523 (2005)
[2] T.D. Cohen, B.A. Gelman, U. van Kolck, Phys. Lett. B 588, 57 (2004)
[3] K.Sone and T.Hyodo, EPJ Web Conf. 291, 05004 (2024)
We will discuss how the confinement potential should be chosen within multi-quark exotic hadrons and what are the effects of the confinement in the spectrum of the tetra-quarks with heavy quark(s). We show the results from the complex scaling method calculation of the tetra-quark systems with the full coupling to the two-meson thresholds.
Since singly heavy baryons and doubly heavy tetraquarks contain two light quarks, they are expected to exhibit well-developed (light-)diquark structures. The properties of light diquarks are affected by spontaneous chiral symmetry breaking and serve as a sensitive probe for investigating the unknown property of the QCD vacuum.
In this talk, we will discuss the spectroscopic properties of heavy hadrons, where we construct a chiral effective model implementing chiral-partner structures of light diquarks (e.g., scalar/pseudoscalar diquarks [1] or vector/axialvector diquarks [4]) and apply this model to heavy-baryon spectra [1,2,4], heavy-baryon decays [3,6], and heavy tetraquarks [5].
[1] M. Harada, Y.-R. Liu, M. Oka, and KS, Phys. Rev. D101, 054038 (2020).
[2] Y. Kim, E. Hiyama, M. Oka, and KS, Phys. Rev. D102, 014004 (2020).
[3] Y. Kawakami, M. Harada, M. Oka, and KS, Phys. Rev. D102, 114004 (2020).
[4] Y. Kim, Y.-R. Liu, M. Oka, and KS, Phys. Rev. D104, 054012 (2021).
[5] Y. Kim, M. Oka, and KS, Phys. Rev. D105, 074021 (2022).
[6] Y. Kim, M. Oka, D. Suenaga, and KS, Phys. Rev. D107, 074015 (2023).
The nontrivial quark structure of light scalar mesons f0(500), f0(980) and a0(980) remains controversial for many years. In passed years, BESIII has collected 8.0 and 7.33 fb^-1 of e+e- collision data samples at 3.773 and 4.178-4.226 GeV, respectively. In this talk, we will review all the studies about light scalar mesons via semileptonic D decays at BESIII. These studies includes the decays D0 -> a0(980)- e+nu, D+ -> a0(980)0 e+nu, Ds+ -> a0(980)0 e+nu, D+ -> f0(500) l+nu, D+ -> f0(980) e+nu, and Ds+ -> f0(500)/f0(980) e+nu. A short outlook would be given based on BESIII new data in the future.
The origin of the EMC effect is one of the major unsolved problems in nuclear physics. Recent studies suggest that the EMC and Short Range Correlation (SRC) are correlated, and quantitative relations are obtained. In this talk, I will introduce our recent work on the EMC effect for the gluon and its correlation with the SRC. We explore the gluon EMC effect through heavy flavor production in DIS, and the SRC through sub-threshold photoproduction of J/Ψ. Based on an effective field theory (EFT) analysis, we derive a linear relation between the gluon EMC effect and the SRC scaling factor measurements. Examining this relation at future experimental facilities such as electron-ion collider (EIC) can help to accomplish the long-standing quest for the nucleon sub-structure.
The NA62 experiment at CERN collected the world's largest dataset of charged kaon decays in 2016-2018, leading to the first measurement of the branching ratio of the ultra-rare $K^+ \rightarrow \pi^+ \nu \bar\nu$ decay, based on 20 candidates.
In this talk NA62 reports new results from the analyses of rare kaon and pion decays, using data samples collected in 2017-2018. A sample of $K^+ \rightarrow \pi^+ \gamma \gamma$ decays was collected using a minimum-bias trigger, and the results include measurement of the branching ratio, study of the di-photon mass spectrum, and the first search for production and prompt decay of an axion-like particle with gluon coupling in the process $K^+ \rightarrow \pi^+ A$, $A \rightarrow \gamma \gamma$. A sample of $\pi^0 \rightarrow e^+ e^-$ decay candidates was collected using a dedicated scaled down di-electron trigger, and a preliminary result of the branching fraction measurement is presented. Recent results from analyses of $K^+ \rightarrow \pi^0 e^+ \nu \gamma$ and $K^+ \rightarrow \pi^+ \mu^+ \mu^-$ decays using 2017--2018 datasets are also presented. The radiative kaon decay $K^+ \rightarrow \pi^0 e^+ \nu \gamma$ (Ke3g) is studied with a data sample of O(100k) Ke3g candidates with sub-percent background contaminations. Results with the most precise measurements of the Ke3g branching ratios and T-asymmetry are presented. The $K^+ \rightarrow \pi^+ \mu^+ \mu^-$ sample comprises about 27k signal events with negligible background contamination, and the presented analysis results include the most precise determination of the branching ratio and the form factor.
The formalism of colour-Lorentz forces offers a novel approach to understanding the mechanisms that bind quarks into hadrons. We present a lattice QCD calculation of the transverse spatial distribution of the colour-Lorentz force acting on a struck quark in a proton. Utilising $N_f=2+1$ flavors of dynamical fermions at the SU(3) symmetric point across three lattice spacings, we identify a central, spin-independent confining force, alongside spin-dependent force distributions. The local forces are observed to exceed the scale associated with the QCD string tension, offering new insights into quark confinement and hadron structure. Further, our results are shown to provide a complementary perspective on the Sivers asymmetry observed in transversely polarized deep-inelastic scattering.
COMPASS is the longest-running experiment at CERN, with a record-breaking 20 years of data collection from 2002 to 2022. The experiment has a unique and diverse physics program focused on nucleon structure and spectroscopy measurements.
The experimental results obtained by COMPASS during Phase I (2002-2011) and Phase II (2012-2022) for a wide range of nucleon spin structure-related DIS and Drell-Yan measurements play an essential role in the general understanding of the three-dimensional nature of the nucleon. In 2022, the experiment concluded its final data-taking phase, which focused on the study of transverse spin phenomena in semi-inclusive measurements of hadron production in DIS. This was conducted using a high-energy muon beam and a transversely polarized deuteron target. This talk will review selected highlights from the COMPASS legacy on longitudinal and transverse nucleon spin structure studies and address recent results and prospects with the COMPASS successor, the AMBER experiment.
The Quark-Meson Coupling (QMC) model describes a self-consistent relationship between the dynamics of the quark structure of a nucleon and the relativistic mean fields arising within the nuclear medium. The model has been successful in computing ground-state observables of finite nuclei and in predicting properties of dense nuclear matter and non-rotating neutron stars. This presentation will focus on the most recent model predictions for the superheavy region, encompassing energies and deformations. The results have shown consistent improvement as the model evolved, comparable to those from other nuclear models, despite employing significantly fewer model parameters.
The results on recent studies of nuclear dynamics at extremely large internal
momenta in the deuteron are presented. We demonstrate that the paradigm shift
in the description of the deuteron consisting of proton and neutron to the description of
the deuteron as a pseudo-vector composite system in which proton and neutron is
observed in high energy electro-disintegration processes results in the emergence of
a new structure. We demonstrate that this new structure can exist only if it emerged from
pre-existing non-nucleonic component in the deuteron. The study of the dynamics of the
predicted new structure is presented focusing on the question if it allows to understand
the anomaly observed in the recent experiment at Jefferson Lab that probed deuteron
structure at internal momenta above 800 MeV/c.
The newly completed Stawell Underground Physics Laboratory (SUPL) in the Stawell Gold Mine will host rare event physics searches, including the dark matter direct detection experiment SABRE South, as well as low background experiments such as radiobiology and quantum computing. Neutrons present an important background to the experiments within SUPL, their penetrating power and neutral charge allows them to mimic signal events within detectors. The neutron monitoring system is being developed at the University of Adelaide, based on Bonner sphere detectors. An array of three He-3 neutron detectors, taking measurements from within 12 Bonner Spheres, will allow the neutron flux within the laboratory to be measured. The polyethylene spheres act as neutron moderators and range in size from 2.5 to 18 inches. Unfolding of the count rate in each sphere is used to calculate the neutron flux of the environment in energies from 10^2eV through to 10^7eV. The detectors have been successfully tested using a neutron source at the University of Adelaide and work is ongoing to develop a system for operation in the remote, limited access, environment of SUPL. This talk will report on the current status of the neutron monitoring system and its ongoing development.
The low-energy QCD, the theory within the Standard Model describing the strong interaction, is still missing fundamental experimental results to achieve a breakthrough in its understanding. Among these, the low-energy kaon-nucleon/nuclei interaction studies are playing a key-role.
Combining the excellent quality of the low-energy kaon beam delivered by the DANE collider of INFN-LNF with new experimental techniques, like high-precision spectroscopic Silicon Drift Detectors, we performed unprecedented measurements in the low-energy strangeness sector in the framework of the SIDDHARTA Collaboration and are presently running the SIDDHARTA-2 experiment for very challenging kaonic atoms measurements, such as kaonic deuterium first measurement.
I shall introduce the physics of kaonic atoms, the experiment, the first exciting results, and discuss future plans. I shall also present AMADEUS collaboration results on studies of low-energy kaons interacting with various nuclei.
The experiments at DANE represent a unique opportunity to unlock QCD secrets in the strangeness sector and contribute to better understand the role of strangeness in the Universe, from nuclei to the stars.
The neutron lifetime anomaly speaks to the possibility of exotic decay channels of the neutron. The very existence of neutron stars constrains the strength of such effects, and in this talk I develop how precisely determined energy-loss constraints, particularly anomalous binary-pulsar period lengthening, limit not only the total baryon loss rate across the star but also the parameters of the particle physics models that can produce such loss. To do this, we compute the new processes in the dense nuclear medium found at the core of a neutron star, employing the techniques of relativistic mean-field theory. Focusing on scenarios in which the dark-sector particles do not accumulate in the star, we extract limits on in-vacuum exotic neutron decays, and we determine them for various equations of state, noting their implications.
At the TeV scale, low-energy precision observations of neutron characteristics provide unique probes of novel physics. Precision studies of neutron decay observables are susceptible to beyond the Standard Model (BSM) tensor and scalar interactions, while the neutron electric dipole moment, $d_n$, also has high sensitivity to new BSM CP-violating interactions. To fully utilise the potential of future experimental neutron physics programs, matrix elements of appropriate low-energy effective operators within neutron states must be precisely calculated. We present results from the QCDSF/UKQCD/CSSM collaboration for the isovector charges $g_T$ , $g_A$ and $g_S$ of the nucleon, $\Sigma$ and $\Xi$ baryons using lattice QCD methods and the Feynman-Hellmann theorem.
We detail dispersive evaluations of various window quantities relevant to the determination of the HVP contribution to the anomalous magnetic moment of the muon in the Standard Model, and compare these to lattice evaluations of the same quantities. Of particular interest are the light-quark connected window quantities, where dispersive results obtained using data prior to the new CMD-3 2-pion cross-section results show sizeable discrepancies with lattice results. We also show that replacing the old 2-pion data with the CMD-3 in the region where the latter is measured removes all these discrepancies.
I will discuss the first lattice QCD calculation of the universal axial γW-box contribution to both superallowed nuclear and neutron beta decays. This contribution emerges as a significant component within the theoretical uncertainties surrounding the extraction of |Vud| from superallowed decays, thereby making an important impact on the precision test of the first-row CKM unitarity.
A method to sum over (unknown) final states is proposed in
the lattice QCD calculation. Systematically improvable in principle,
but it induces new problems, including the one related to the
approximation of the kernel function. Potential applications other than
the inclusive decays will be discussed too.
Numerical methods for exploring high-dimensional parameter spaces are crucial across a wide variety of scientific fields, including:
This pedagogical talk will discuss the theoretical challenges of exploring high-dimensional parameter spaces, a practical framework for assessing the performance of different sampling algorithms, and scientific case-studies from the fields above. We will focus the discussion around the ScannerBit module of the GAMBIT global fitting framework, which includes a variety of sampling algorithms for both Frequentist and Bayesian analyses. In particular we will highlight ScannerBit 2.0 which incorporates a python interface to state-of-the-art sampling algorithms alongside the tried-and-tested Differential evolution (Diver) and Nested sampling methods (MultiNest & PolyChord).
In a high energy physics experiment, a straightforward approach to estimating the dependency of a distribution of events on a nuisance parameter is to take the difference of histograms of the distribution coming out of a simulation before and after perturbing the value of the nuisance parameter. This is often done by perturbing one already simulated event at a time by a small post-simulation correction, due to e.g. a change of energy scale or energy resolution. This leads, unfortunately, to uncomfortably large statistical fluctuations, as the perturbed events move discontinuously from one histogram bin to the next. These fluctuations are frequently dealt with by a smoothing technique, which is pain-staking to validate. In this work we focus on the first and second moments of the small movements of the events to more directly estimate the shape dependence on the nuisance parameter. A fundamental assumption, and limitation, of this approach is that there is no hidden dependence one the acceptance on the nuisance parameter, i.e., events may move around in the distribution but events do not leave or enter the analysis acceptance except at the edges of the histogram. The approach could, however, prove useful for precision shape-dependent measurements of, for example, the mass of the W boson. Toy studies illustrate the potential of the approach.
Quantifying tension between different experiments aiming to constrain the same physics is essential for validating our understanding of the world around us. A commonly used metric of tension is the evidence ratio statistic, R, corresponding to the ratio of a joint evidence to the product of individual evidences under a common model. R can be interpreted as the fractional increase in our confidence in a dataset given knowledge of another. While R has been widely adopted as an appropriately Bayesian way of quantifying tensions, it has a non-trivial dependence on the prior that is not always accounted for properly. In this work, we propose using Neural Ratio Estimators (NREs) to calibrate the prior dependence of the R statistic. We show that the output of an NRE corresponds to R if the inputs correspond to data sets from two different experiments. We then show that with an appropriately trained NRE one can derive the distribution of all possible in concordance values of R for two experiments given a model and prior choice. One can then calibrate one's observed R, derived via an independent method such as Nested Sampling, against this distribution to derive a prior independent estimate of tension.
We describe a software pipeline that models atmospheric gamma and hadron showers and their detection and reconstruction by an array of Cherenkov detectors on the ground, as well as the calculation of a utility function aligned with the scientific goals of the SWGO experiment. The variation of the utility with the position of each detector on the ground allows to perform stochastic gradient descent to an optimal layout. This epitomizes the concept of co-design for future experiments in fundamental science.
Particle physics experiments often rely on statistical hypothesis testing to determine statements of discovery, evidence, or exclusion, typically assessed through p-values, "number of sigmas." However, in many cases, the significance is evaluated using asymptotic formulae based on Wilk's Theorem, without guarantees that its conditions are fulfilled. Alternatively, p-values can be assessed using simulations, "toy Monte Carlo" but extending this technique to achieve the customary 5-sigma threshold required for a discovery is often impractical.
To address this challenge, we propose a method based on importance sampling, which allows for estimation via simulation while reducing the required sample size by orders of magnitude. Specifically, we suggest sampling from a signal-like probability distribution, and we demonstrate that, for a broad range of scenarios, this approach optimally minimizes variance.
We will outline the mathematical proofs supporting this method and discuss its application to various synthetic examples. Additionally, we will explore the feasibility of implementing this approach in realistic experimental settings.
We investigate the vacuum structure of SU(3) Yang-Mills theory on the lattice in the presence of chromometallic mirrors both at zero and finite temperatures in 3+1 dimensions. The new excitation at the boundaries with the mass $m_{gt} = 1.0(1)\sqrt{\sigma}=0.49(5)$GeV which is more than three times lighter than mass of $0^{++}$ groundstate glueball was uncovered. We call this excitation "glueton" and interpret it as a non-perturbative colorless gluonic state of two gluons bound to their negatively colored images in a chromometallic mirror. The glueton is a gluonic counterpart of a surface electron-hole exciton in semiconductors. Additionally, we show that a heavy quark is linearly attracted to the mirror, and it presumably forms a "quarkiton" ("quark exciton") colorless state with its anti-quark image in the chromometallic mirror.
In this talk, we explore the QCD vacuum structure with topological theta angle, employing a novel semiclassical framework on $\mathbb{R}^2 \times T^2$ with 't Hooft and baryon magnetic fluxes. Grounded in the adiabatic continuity conjecture, the semiclassical analysis at small $T^2$ can capture the QCD vacuum structure, and the confining vacuum is described by the dilute gas of center vortices. Our 2d effective theory at small $T^2$ explains a plausible $\theta$-dependence of the QCD vacuum: (1) The one-flavor QCD exhibits the $CP$-broken two-fold degenerate vacua at $\theta =\pi$ for quark mass above a critical value, and (2) the multi-flavor QCD shows the $CP$-breaking at $\theta =\pi$ for all (degenerate) quark masses. This 2d effective theory can be regarded as a 2d analog of the chiral Lagrangian with periodicity-extended eta prime. Intuitively, eta prime extends its periodicity by "eating" the $\mathbb{Z}_N$ SPT label of the $SU(N)$ Yang-Mills vacuum. Based on this observation, we point out that the periodicity extension of eta prime can improve the consistency of the $4$d chiral Lagrangian with known global structures, such as discrete anomalies.
The Schwinger model (QED in 1+1 dims) describes confinement and nontrivial $\theta$ vacuum similar to QCD. In this presentation, I quantitatively reveal the confining properties in the Schwinger model at finite temperature and $\theta$ using the Monte Carlo method. The well-known sign problem is avoided using bosonization, in which the Dirac fermion is transformed into a scalar boson. We observe that the string tension for noninteger probe charge becomes negative near $\theta = \pi$ at low temperatures, which can be understood by the creation of a dynamical charge pair.
Reference:
H. Ohata, “Monte Carlo study of Schwinger model without the sign problem,”
JHEP 12 (2023) 007, arXiv:2303.05481.
Filtering methods based on adjoint fermion zero modes are presented in this talk. The theoretical foundations and relations of supersymmetric theories are discussed and results from Monte Carlo data are presented. Furthermore, some specific properties of Yang-Mills theories with twisted boundary conditions are introduced, which lead to an interesting approach for a better understanding of vacuum and confinement.
This presentation will focus on defining the net topological charge within distinct topological objects in the nontrivial ground-state fields of $\mathrm{SU}(N)$ lattice gauge theory. Such an analysis has been called for by the growing number of models for Yang-Mills topological structure which propose the existence of fractionally charged objects. We perform this investigation for $\mathrm{SU(3)}$ colour at a range of temperatures across the deconfinement phase transition, providing an assessment of how the topological structure evolves with temperature. This reveals a connection between the topological charge and holonomy of the system which must be satisfied by finite-temperature models of QCD vacuum structure. We then proceed to discuss instanton-dyons, one such model which exhibits a promising consistency with our results. To conclude, we will present preliminary findings for the gauge groups $\mathrm{SU(2)}$ and $\mathrm{SU(4)}$ at zero temperature to analyse the dependence of the topological structure on the number of colours.
While the mandate of particle physics research institutes is fundamental research, the developed technologies find applications for the benefit of society. With the aim to highlight their impact on medical applications and in particular on cancer treatment, the new Particle Therapy MasterClass (PTMC) package was developed and integrated into the International MasterClass 2021 (IMC) online programme, attracting immediately some 37 institutes from 20 countries and more than 1500 students. The PTMC, focusing on the topic of cancer treatment, a particular sensitive topic, is becoming increasingly popular, attracting the interest of students and tutors alike. The main idea is to show that (a) fundamental properties of particle interactions with matter, which are used to detect them in physics experiments, are also the basis for treating cancer tumours; and (b) the same accelerator technologies are used in both research laboratories and therapy centres. Ultimately students are shown “what physics has to do with medicine” and what are the various possibilities that physics and STEM studies may open up for job opportunities in fields that there is lack of expert personnel.
The ARC Centre of Excellence for Dark Matter Particle Physics has developed a partner school program to build long-term collaborations with traditionally underserved regional and rural schools in Australia. Now in its fourth year, this program has expanded to seven schools across two states.
In this session, we will discuss: The inspiration, drive, and support behind the development of the program; The structure of the program and its alignment with the centre’s scientific research; An overview of the scaffolded and curriculum-aligned lessons covering topics such as gravity, the galaxies, the nature of science, and particle models; and an update on the evaluation of the efficacy of the program in conjunction with the University of Melbourne Faculty of Education.
There have been rapid developments in the direct calculation in lattice QCD (LQCD) of the Bjorken-x dependence of hadron structure through large-momentum effective theory (LaMET) and other similar effective approaches. These methods overcome the previous limitation of LQCD to moments (that is, integrals over Bjorken-x) of hadron structure, allowing LQCD to directly provide the kinematic Bjorken-x regions where the experimental values are least known. In this talk, I will show some selected recent progress along these directions and examples of how including lattice-QCD calculations in the global QCD analysis can play a significant role in improving our understanding of parton distributions in the future.
In high energy collision experiments with multiple hadron productions, the momentum distribution of the measured hadron pair shows a correlation due to the hadron interactions and the quantum statistics. In the past, this femtoscopy technique has been developed to extract the information of the emission source from the momentum correlation functions. Recently, correlation function measurement is utilized also as a new method to determine the hadron interactions. In fact, the ALICE collaboration at LHC measures the correlation functions with various hadron pairs, for which the standard scattering experiment is difficult, providing remarkable progress in the study of the hadron scattering. In this talk, we introduce the basics of theoretical method to calculate the momentum correlation function [1], and present recent applications to antikaon-nucleon systems [2] and hypernuclei [3], including future prospects at J-PARC.
[1] S. Cho et al., ExHIC collaboration, Prog. Part. Nucl. Phys. 95, 279 (2017).
[2] Y. Kamiya, T. Hyodo, K. Morita, A. Ohnishi, W. Weise, Phys. Rev. Lett. 124, 132501 (2020).
[3] A. Jinno, Y. Kamiya, T. Hyodo, A. Ohnishi, arXiv:2403.09126 [nucl-th].
In this talk I review our current understanding of the interior of neutron stars and modern constraints relevant for dense matter. This includes theoretical first-principle results from lattice and
perturbative QCD, as well as chiral effective field theory results. From the experimental side, it includes heavy-ion collision and low-energy nuclear physics results, as well as observations from neutron stars and their mergers.
In recent years, many vector charmonium(-like) states were reported by different electron-positron collider experiments above 4.2 GeV. However, so far, there not only exists sizable tension in the parameters of those states, but there is also no consensus on the number of the vector states in this energy range.
In this talk, we focus on the mass range between 4.2 and 4.35 GeV, conducting a comprehensive analysis of eight different final states in e +e − annihilation. Our findings demonstrate that, within this mass range, a single vector charmonium-like state, exhibiting properties consistent with a D1D molecular structure, can effectively describe all the collected data. This is made possible by allowing for an interference with the well-established vector chamonium ψ(4160) along with the inclusion of the D1D threshold effect.
We study the system of light mesons, charmonium and glueballs in the flavour singlet channels where they can mix. We use lattice QCD simulations with an almost physical charm quark and three degenerate light quarks for two values of the pion mass ($m_{\pi} \approx 420, 800$ MeV). Thanks to a variational basis which includes mesonic operators with profiles in distillation space, Wilson loops and two-pion operators we detect and show results of their mixing.
A singly heavy baryon can be viewed as a bound state of $N_c-1$ valence quarks in a pion mean-field approach, a heavy quark being regarded as a static color source. This aspect provides a great virtue of dealing with both light and singly heavy baryons on an equal footing. The presence of $N_c-1$ valence quarks polarizes the vacuum and produces pion mean fields, by which the $N_c-1$ valence quarks are influenced self-consistently. In this picture, the mass spectrum of singly heavy baryons is well described. In the current talk, we present a series of recent investigations on electromagnetic and axial-vector properties of the singly heavy baryons with both spin 1/2 and 3/2. We compare the numerical results with those from lattice data. We finally discuss possible future works on the physics of heavy baryons.
Owing to the color confinement, the phenomena of strong interaction physics can be described either in terms of fundamental quarks and gluons of Quantum Chromodynamics (QCD) or as mesons and baryons and the nuclear force between them. Mesons and baryons themselves are confined dynamic systems of quarks and gluons. Understanding fully the relationship between this dual representation of strong interaction physics requires us to explore the inner structure of nucleons and nuclei and its emergence from QCD dynamics. In this talk, I will review the opportunities presented by the current JLab 12 GeV and future EIC research programs, demonstrating that both theory and experimental technology have now reached a point where we can explore the inner structure of nucleons and nuclei at sub-femtometer distances. This capability allows us to search for answers to the most compelling and fundamental emergent phenomena of the strong interaction physics, leading to the emerging science of nuclear femtography.
The gravitational form factors (GFFs) describe the fundamental structure of nucleons and nuclei through the matrix element of the energy-momentum tensor. Their Fourier transform allows a description of the spatial distribution of mass, angular momentum, pressure, and shear force densities for both quarks and gluons in the nucleon. In this presentation, I will focus on the recent results of the $J/\psi$ photoproduction near-threshold on the proton at Jefferson Lab to determine the elusive ${\it gluonic}$ gravitational form factors (gGFFs) using data from both $J/\psi$ decay channels, electronic and muonic. We'll discuss the caveats of the extraction of these gluonic GFFs in the threshold region and how to validate this extraction with the future SoLID $J/\psi$ and the EIC \Upsilon$ measurements. Both would enable future measurements critical to access the trace anomaly and gain insight into the origin of the nucleon mass
We describe recent developments in the determination of the strong coupling $\alpha_s$ from finite energy sum rule (FESR) analyses of non-strange spectral distributions measured in hadronic $\tau$ decay. This includes details of an isovector, vector channel analysis employing a improved version of the relevant spectral function obtained via use of a recent BaBar determination of the $\tau\rightarrow K\bar{K} \nu_\tau$ distribution and improved CVC-based higher-multiplicity distributions obtained using recent electro-production cross-section results. We also use this improved spectral function to explore recently debated systematic issues in past FESR determinations, as well as describing new developments clarifying the understanding of what is actually learned in those determinations, and the modifications this understanding necessitates in the interpretation of those results.
Neutron star physics has wrestled with the longstanding challenge of the hyperon puzzle, attempting to reconcile lowered theoretical predictions of maximum masses due to hyperons with astrophysical observations based on the measured masses of the heaviest pulsars. Recently, we conducted a comprehensive statistical analysis of equations of state (EoSs) for neutron stars with hyperons, including both laboratory data and astrophysical observations. Results from the statistical analysis reveal the important role of the correlations between the scalar and vector channels of hyperon-nucleon interactions deduced from available 𝛬-separation-energy data of single 𝛬 hypernuclei. The analysis preliminarily quantifies uncertainties in hyperon star properties due to the uncertain hyperon-nucleon interaction in dense matter, and the maximum mass of hyperon star is found to be around 2.2 solar masses, challenging the existence of the hyperon puzzle. As part of a broader initiative connecting nuclear physics and astronomy to quantitatively determine neutron star EoS, the study provides valuable insights into the hyperon puzzle and its implications for our understanding of neutron star interiors. Moreover, the investigation addresses the lack of precise knowledge regarding hypersonic interactions, emphasizing the need for additional hypernuclear data through a combined effort involving theory, experiments, and observations.
It has been suggested [1] that the observation of pulsars with the same mass but significantly different radii (twin stars) would prove that the existence of a critical endpoint in the QCD phase diagram since this phenomenon requires a strong phase transition in cold neutron star matter.
We explore whether such a phase transition in neutron star cores, possibly coupled with a secondary kick mechanism such as neutrino or electromagnetic rocket effect, may provide a formation path for isolated and eccentric millisecond pulsars (MSPs) [2].
We find that in compact binary systems (Porb = 8 days) the accretion-induced phase transition occurs towards the end of mass transfer, specifically during the spin equilibrium phase. In contrast, in binary systems with wider orbits (Porb ≃ 22 days), this transition takes place during the subsequent spin-down phase, leading to a delayed collapse. We find that a gravitational mass loss of approximately ∆M ∼ 0.01 M⊙ suffices to produce an eccentricity of the order of 0.1 without the need of a secondary kick mechanism. Wider systems are more prone to yielding highly eccentric orbits and be disrupted, presenting a formation path for isolated MSPs [2].
We show that in hot neutron star matter, at constant entropy per baryon s/n_B ~ 2, thermal twin stars can exist [3], even when in the mass-radius diagram of cold neutron stars the branch of hybrid stars with color superconducting quark matter cores is connected (no twins) to that of pure neutron stars. Investigating systematically star sequences for increasing s/n_b = const, we find a correlation
between the transition to normal quark matter cores, the change from enthalpic to entropic character of the transition and the occurrence of thermal twin stars. We speculate about a correlation of the thermal twin phenomenon with the supernova explodability of massive blue supergiant stars [3].
[1] D. Blaschke, D. E. Alvarez-Castillo and S. Benic, Mass-radiu constraints for compact stars and a
critical endpoint, PoS CPOD2013 (2013), 063, arXiv:1310.3803 [nucl-th]
[2] S. Chanlaridis et al., Formation of twin stars in low-mass X-ray binaries. Implications on
eccentric and isolated millisecond pulsar populations, in preparation (2024)
[3] J. Carlomagno et al., Hybrid isentropic twin stars, arXiv: 2406.17193 (2024)
Gravitational waves allow us to probe the interiors of both cold and hot neutron stars where potentially exotic states of matter exist. I will review current efforts to observe gravitational waves from merging neutron stars by the LIGO-Virgo-KAGRA collaborations. I will also provide an overview of what this field holds in the next decade with current gravitational-wave observatories, and what is being forecast for the next-generation of observatories slated for operation in the 2030s.
Observables that violate lepton flavor symmetry are sensitive probes of physics beyond the Standard Model (BSM), since any observation would be a clear BSM signal. Limits on $\mu\to e$ conversion in nuclei are amongst the most stringent ones available, and are even expected to improve by up to four orders of magnitude at Mu2e and COMET. In this talk, I will discuss, based on an effective-field-theory analysis, how the spin-dependent process already implies indirect limits on lepton-flavor-violating decays of light pseudoscalars that surpass direct limits by orders of magnitude. I will also comment on the nuclear-structure input required for a robust interpretation of $\mu\to e$ conversion limits.
The forthcoming Mu2e and COMET experiments will search for electrons produced via the neutrinoless conversion of muons captured onto the atomic nucleus $^{27}$Al, improving existing limits on charged lepton flavor violation (CLFV) by roughly four orders of magnitude and probing new physics at scales in excess of 10,000 TeV. Many proposed extensions of the standard model give rise to observable CLFV. If a positive signal is observed at Mu2e/COMET, a follow-up program of $\mu\rightarrow e$ conversion experiments with different target nuclei can be used to further constrain the form of the new physics.
Connecting the results of these experiments, which are performed at relatively low energies, to candidate UV theories formulated at very high energies is a significant theoretical challenge. We describe a tower of effective field theories that bridges this gap, providing a complete description of $\mu\rightarrow e$ conversion and allowing one to predict experimental rates for arbitrary UV theories. A crucial set of inputs to this framework are the numerical values of form factors describing the nonperturbative matching between quarks and nucleons.
We propose a new approach to search for light dark matter (DM) in the mass range of keV-GeV via inelastic nucleus scattering at large-volume neutrino detectors such as Borexino, DUNE, JUNO, and Super-/Hyper-K. The approach uses inelastic nuclear scattering of cosmic-ray boosted DM, enabling a low-background search for DM in these experiments. The large-volume neutrino detectors with higher threshold can be used since the nuclear de-excitation lines are $O(10)$ MeV. Using a hadro-philic dark-gauge-boson-portal model as a benchmark, we show that the nuclear inelastic channels generally provide better sensitivity than the elastic scattering for a large region of light DM parameter space.
The geometry of centre vortices is studied in SU(3) lattice gauge theory at finite temperature to capture the key structural changes that occur through the deconfinement phase transition. Visualisations of the vortex structure in temporal and spatial slices of the lattice reveal a preference for the vortex sheet to align with the temporal dimension above the critical temperature. This is quantified through a correlation measure. A collection of vortex statistics, including vortex and branching point densities, and vortex path lengths between branching points, are analysed to highlight internal shifts in vortex behaviour arising from the loss of confinement. We find the zero-temperature inclination of branching points to cluster at short distances vanishes at high temperatures, embodying a rearrangement of branching points within the vortex structure. These findings establish the many aspects of centre vortex geometry that characterise the deconfinement phase transition in pure gauge theory.
In this talk, we revisit the idea proposed by one of us in PRD 98 036018 (2018) where the nonoriented component, in 4d ensembles of percolating thin center-vortex worldsurfaces, was shown to be essential to understand the properties of confinement at asymptotically large distances between heavy quarks. The same physics was reobtained in the Schrödinger's wave (functional) representation PRD 106 114021 (2022), which deals with center-vortex lines and pointlike monopoles in 3d real space. In the present contribution, the 4d ensemble is reassessed by means of Weingarten's lattice representation for the sum over oriented surfaces. In the percolating phase, stabilized by repulsive interactions, the emergence of lattice gauge fields as the Goldstone modes for the oriented center-vortex condensate is straightforward. In addition, worldsurfaces attached to monopole worldlines (nonoriented component), as well as their fusion rules, can be easily characterized in the lattice. Thus, the original mechanism, where the Wilson loop ensemble average was given by an effective 4d Yang-Mils-Higgs model with frustration, is neatly confirmed. In this mechanism, percolating oriented and nonoriented center vortices trigger the formation of a flux tube that conciliates N-ality with Abelian-like profiles and one of the possible asymptotic scaling laws (Casimir).
A study of centre vortices and gluon propagators is presented on anisotropic, dynamical lattices. We use thermal ensembles from the FASTSUM collaboration and results are discussed in both the confined and deconfined phases. Centre vortices are analysed including their percolation and branching point properties, and an analysis of the Landau gauge-fixed gluon propagators is presented. Issues surrounding gauge fixing in the anisotropic case are outlined..
The quark-hadron transition that happens in ultra-relativistic heavy-ion collisions is expected to be influenced by the effects of rotation and magnetic field, both present due to the geometry of a generic non-head-on impact. We augment the conventional $T$-$\mu_B$ planar phase diagram for QCD matter by extending it to a multi-dimensional domain spanned by temperature $T$, baryon chemical potential $\mu_B$, external magnetic field $B$ and angular velocity $\omega$. Using two independent approaches, one from a rapid rise in entropy density and another dealing with a dip in the speed of sound, we identify deconfinement in the framework of a modified statistical hadronization model. We find that the deconfinement temperature $T_C(\mu_B,~\omega,~eB)$ decreases nearly monotonically with increasing $\mu_B,~\omega$ and $eB$ with the most prominent drop (by nearly $40$ to $50$ MeV) in $T_C$ occurring when all the three quasi-control (collision energy and impact parameter dependent) parameters are tuned simultaneously to finite values that are achievable in present and upcoming heavy-ion colliders. We discuss the possibility of having phenomenological probes acting as magnetometer and anemometer in heavy-ion collisions.
We study one-flavor $\mathrm{SU}(2)$ and $\mathrm{SU}(3)$ lattice QCD in ($1+1$) dimensions at zero temperature and finite density using matrix product states and the density matrix renormalization group. We compute physical observables such as the equation of state, chiral condensate, and quark distribution function as functions of the baryon number density. As a physical implication, we discuss the inhomogeneous phase at nonzero baryon density, where the chiral condensate is inhomogeneous, and baryons form a crystal. We also discuss how the dynamical degrees of freedom change from hadrons to quarks through the formation of quark Fermi seas.
We discuss the QCD phase diagram in strong magnetic fields, where the chiral condensate is enhanced by the magnetic catalysis mechanism. In contrast to the conventional discussions, we include heavy-quark impurities that have been known to induce the Kondo effect. We propose a quantum critical point that arises as a consequence of the Kondo effect and the chiral symmetry breaking. Our phase diagram is obtained from a self-consistent determination of the magnitudes of the chiral condensate and the Kondo condensate, which is a particle pairing composed of conducting Dirac fermions and localized impurities. We also discuss finite-temperature effects and implications for condensed matter physics including bilayer graphene.
Koichi Hattori, Daiki Suenaga, Kei Suzuki, Shigehiro Yasui, "Dirac Kondo effect under magnetic catalysis," Phys.Rev.B 108 (2023) 24, 245110. 2211.16150 [hep-ph]
Diquarks are often invoked as QCD effective degrees of freedom to describe baryons as well as certain exotic hadrons. However, even though they are successful in describing many of these low lying QCD states, they and their properties have been difficult to pin down. Here we present progress in studying diquarks in a gauge-invariant setup through embedding them in a parent hadron containing a heavy spectactor quark using lattice QCD calculations.
A dominant source of uncertainty in theoretical determinations of ratios of inclusive lifetimes of heavy hadrons are 'Spectator Effects', wherein the light degrees of freedom participate in the decay process. The heavy-quark-expansion describes these effects as matrix elements of four-quark HQET operators in the heavy hadron states of interest. Using a recently developed position-space scheme to nonperturbatively renormalize these operators in lattice-HQET, we present updates on the spectator effect matrix elements.
The renormalization group (RG) beta function characterizes the nature of gauge-fermion systems, describes the running of the renormalized coupling, and connects ultraviolet and infrared regimes of quantum field theories. We use the RG beta function as a tool to explore how gauge-fermion systems with SU(3) gauge group change, when the number of fundamental flavors increases. Using lattice field theory simulations, we aim to establish nonperturbatively e.g. whether a theory with $N_f$ fundamental flavors is conformal exhibiting an infra-red fixed point. Of special interest for constructing BSM theories is to identify the onset of the conformal window. Presently SU(3) with eight fundamental flavors is in the spotlight of our investigations because tantalizing signs of a new phase have emerged.
The Lambda parameter of three flavor QCD is obtained by computing the running of a renormalized finite volume coupling from hadronic to very high energies where connection with perturbation theory can safely be made.
The theory of decoupling allows us to calculate the running of the
coupling in pure gauge theory. The missing piece is then an accurate matching of a massive three flavor coupling with the pure gauge one, in the continuum limit of both theories. A big challenge is to control the simultaneous continuum and decoupling limits, especially when chiral symmetry is broken by the discretization.
Recent lattice QCD results for the low-lying positive parity $\Delta$ spectrum indicate that the $2s$ excitation of the ground state $\Delta(1232)$ lies at ~2.15 GeV. This sits significantly above the experimentally measured mass of the first positive parity excitation, the $\Delta(1600)$. Using Hamiltonian Effective Field Theory (HEFT), the $1s$ and $2s$ states are represented by single-particle bare basis states, mixing through $\pi N$ and $\pi\Delta$ scattering channels. Constraining this Hamiltonian to $p$-wave $\pi N$ scattering data, we extract the finite-volume energy spectrum for this system at unphysical pion masses. This allows for comparison with recent lattice QCD results, providing insight into the structure of lattice QCD eigenstates through the eigenvectors of the Hamiltonian. This method indicates that the eigenstate associated with the $\Delta(1600)$ is dominated by $\pi N$ and $\pi\Delta$ rescattering contributions, rather than the dressing of a three-quark-like core as previously considered in literature.
For over seventy years, the internal structure of the proton has been studied using electromagnetic interactions to measure elastic form factors. The quark structure has been explored for over fifty-five years, and the helicity structure for over forty years. However, our understanding of the proton’s mechanical properties—such as internal mass distribution, angular momentum, pressure, and shear stress—remains limited. These properties are encoded in gravitational form factors. In this talk, we will present the pioneering extraction of the pressure and force distribution within the proton. Additionally, we will discuss ongoing and future experiments aimed at achieving a more precise understanding of the proton’s mechanical properties.
In this talk, I will present our recent work on two-loop QCD corrections to pion electromagnetic form factors with large momentum transfer.
We explicitly verify the validity of the collinear factorization to two-loop order for this observable, and obtain the respective IR-finite two-loop hard-scattering kernel in the closed form.
Incorporating this new ingredient of correction, we make a comprehensive comparison between the theoretical predictions and pion form factor measurements in both space-like and time-like regions.
Our phenomenological analysis provides constraint on the second Gegenbauer moment of the pion light-cone distribution amplitude
obtained from recent lattice QCD studies.
I will discuss a lattice QCD calculation of the nucleon electric polarizabilities at the physical pion mass. Our findings reveal the substantial contributions of the Nπ states to these polarizabilities. Without considering these contributions, the lattice results fall significantly below the experimental values, consistent with previous lattice studies. This observation has motivated us to compute both the parity-negative Nπ scattering up to a nucleon momentum of ∼ 0.5 GeV in the center-of-mass frame and corresponding Nγ∗ → Nπ matrix elements using lattice QCD. Our results confirm that incorporating dynamic Nπ contributions is crucial for a reliable determination of the polarizabilities from lattice QCD. This methodology lays the groundwork for future lattice QCD investigations into various other polarizabilities.
The nuclear equation of state (EOS) describes varied phenomena, from the distribution of neutrons and protons inside heavy nuclei to the maximum size of neutron stars. The PREX-2 and CREX experiments used parity violating electron scattering to determine the neutral weak form factors for two doubly magic nuclei: 208Pb and 48Ca. These results can be used to cleanly extract a neutron radius and put constraints on parameters in the nuclear EOS. This talk will review the experiments and extraction of neutron skins. Considerations regarding the broader implications and comparisons to other neutron star experimental results will also be provided.
we evaluate the energy loss rate of supernovae induced by the axion emission process 𝜋+𝑝→𝑛+𝑎 with the Δ(1232)resonance in the heavy baryon chiral perturbation theory for the first time. Given the axion-nucleon-Δ interactions, we include the previously ignored Δ-mediated graphs to the 𝜋+𝑝→𝑛+𝑎 process. In particular, the Δ-mediated diagram can give a resonance contribution to the supernova axion emission rate when the center-of-mass energy of the pion and proton approaches the Δ(1232) mass. With these new contributions, we find that for the typical supernova temperatures, compared with the earlier work with the axion-nucleon (and axion-pion-nucleon contact) interactions, the supernova axion emissivity can be enhanced by a factor of 4(2) in the Kim-Shifman-Vainshtein-Zakharov model and up to a factor of 5(2) in the Dine-Fischler-Srednicki-Zhitnitsky model with small tan𝛽 values. Remarkably, we notice that the Δ(1232) resonance gives a destructive contribution to the supernova axion emission rate at high supernova temperatures, which is a nontrivial result in this study.
In the present work we calculate the transition magnetic moments for the radiative decays of $\Delta $ baryon to $proton$ ($\Delta \rightarrow p$) in isospin asymmetric strange hadronic medium at finite temperature using chiral $SU(3)$ quark mean field model. Within the framework of chiral $SU(3)$ mean field model, the properties of baryons in strange isospin asymmetric medium are modified through the exchange of scalar fields ($\sigma$, $\zeta$ and $\delta$) and vector fields ($\omega$, $\rho$ and $\phi$). The isospin asymmetry of the medium is taken into account via scalar-isovector field $\delta$ and vector isovector field $\rho$. We calculate the in-medium masses of quarks, $proton$ and $\Delta$ baryon in asymmetric strange matter within the chiral SU(3) quark mean field model and use these as input in the chiral constituent quark $(\chi CQM)$ model to calculate the in-medium transition magnetic moments for $\Delta \rightarrow p$ transition for different values of isospin asymmetry and strangeness fraction of hot and dense medium. For calculating the transition magnetic moments, valance, sea and orbital contributions to the magnetic moment are considered in these calculations.
When continuous symmetry is spontaneously broken, the system supports gapless Nambu-Goldstone modes. As a result, the low-energy real-time dynamics are governed by hydrodynamic theory incorporating these Nambu-Goldstone modes. In this talk, I will introduce a general framework for deriving hydrodynamic equations for symmetry-broken phases and discuss their potential application to dense quark-nuclear matter.
We consider a pure Yang-Mills theory on $\mathbb{T}^2\times\mathbb{R}^2$ with boundary conditions imposed not only in the imaginary time direction but also in one spatial direction, and discuss thermodynamic quantities and their phase structures. The introduction of the boundary condition leads to the breaking of rotational symmetry, resulting in anisotropy of the pressure. Results from lattice QCD simulations [1] show that the anisotropic effect is suppressed until the spatial extension becomes significantly smaller near the critical temperature. This result is a very different behavior from that of massless free boson systems. In order to clarify the mechanism behind this result, we employ an effective model with two Polyakov loops along the time and spatial directions [2]. We show that introducing the interplay of two Polyakov loops well describes the lattice data in the high-temperature region, as suggested in a previous study [3]. Furthermore, we suggest the presence of a new first-order phase transition, which is distinguished from the confinement phase transition.
[1]Masakiyo Kitazawa et al, Phys. Rev. D 99, 094507 (2019)
[2]Daisuke Fujii, Akihiro Iwanaka, Masakiyo Kitazawa and Daiki Suenaga, arXiv:2402.17638 [hep-ph]
[3]Daiki Suenaga and Masakiyo Kitazawa, Phys. Rev. D 107, 074502 (2023)
Loss of unitarity in an effective field theory is often cured by the appearance of dynamical resonances, revealing the presence of new degrees of freedom. These resonances may manifest themselves when suitable unitarization techniques are implemented in the effective theory, which in the scalar-isoscalar channel require making use of the coupled-channel formalism. Conversely, experimental detection of a resonance may provide interesting information on the couplings and constants of the relevant effective theory. By applying a systematical procedure we shall try to confront the efective theory with the absence or presence of resonances at the LHC in the vector boson fusion channel.
The SABRE experiment aims to provide a definitive answer on the nature of the purported dark matter annual modulation signal from the DAMA/LIBRA experiments. Their 12.9𝜎 measurement remains incompatible with null results of other dark matter experiments. By relying on ultra-pure NaI(Tl) crystals and dual hemisphere locations, the SABRE experiment will provide a model independent test.
SABRE’s two detector setup, one in the Northern Hemisphere (LNGS, Italy) and one in the Southern Hemisphere (SUPL, Australia), provides a robust method to account for seasonal effects which might be insufficiently understood.
In the SABRE-South experiment the NaI(Tl) crystals are submerged in a veto vessel containing 10 tonnes of liquid scintillator. This vessel is instrumented with 18 photomultiplier tubes (PMTs) to efficiently detect and reject background events.
PMTs should be meticulously calibrated to achieve optimal veto efficiency and monitor the optical properties of the liquid scintillator over time.
This talk focuses on the ongoing optical calibration of veto PMTs and their performance as a whole of the veto system as well as their independent characteristics.
We present a unified approach to the transition from hadronic matter to quark matter where hadrons are treated as bound states of quarks which dissociate at high densities due to quark Pauli blocking. We demonstrate that a sudden switch of the quark mass from a sufficiently high value to mimic quark confinement to its current mass value is compatible with a smooth crossover behavior of the chiral condensate and agrees well with the results of recent lattice QCD simulation for 2+1 flavors. The newly developed approach makes use of a cluster virial expansion formulated in terms of a generalized Φ-derivable approach to multi-quark correlations with bound and continuum states in their spectrum [1]. Our model can be used to obtain thermodynamic functions, consistent with lattice QCD simulations at zero chemical potential, also at finite chemical potentials where lattice QCD simulations have the sign problem. Conclusions for the chemical freeze-out of multi-quark clusters in heavy-ion collisions as well as for primordial black hole formation and compact star evolution are drawn.
[1] D. Blaschke, M. Cierniak, O. Ivanytskyi, G. Röpke, Thermodynamics of quark matter with multiquark clusters in an effective Beth-Uhlenbeck type approach, Eur. Phys. J. A 60 (2024) 14
Motivated by color-magnetic instability in QCD [1,2], we investigate spatial color-magnetic correlation in SU(2) and SU(3) lattice QCD. In the Landau gauge, we numerically obtain the spatial color-magnetic correlation $\langle H_z^a({\bf x}) H_z^a({\bf x}+{\bf r})\rangle$. Curiously, the correlation is found to be always ${\it negative}$ for ${\bf r}$ on $xy$-plane, apart from the same-point correlation. This behavior seems fairly different from the Savvidy/Copenhagen vacuum [1,2].
From an analytical expression of the gluon propagator $\langle A_\mu^a(x) A_\mu^a(x)\rangle\propto\frac{e^{-mr}}{r}$ [3] in the Landau gauge, we obtain an analytic form of the magnetic correlation, which agrees with the lattice QCD data.
[1] G.K. Savvidy, Phys. Lett. B71 (1977) 133.
[2] H.B. Nielsen and P. Olesen, Nucl. Phys. B160 (1979) 380.
[3] T. iritani, H. Suganuma and H. Iida, Phys. Rev. D80 (2009) 114505.
We examine a pattern of dynamical chiral symmetry breaking making use of the vacuum energy density as a function of the quark condensate. We compute the vacuum energy density and the quark condensate in the interacting instanton liquid model (IILM) with three-flavor quarks. These computations are performed by using a numerical simulation of the canonical IILM, i.e., the number of instantons and anti-instantons are fixed. We find that chiral symmetry is broken in the U(1)_A anomaly assisted way in the IILM with three-flavor dynamical quarks. Comparing the full and the quenched IILM calculations, we also find the instanton-quark interaction included in the IILM plays a crucial role for the chiral symmetry breaking.
In the lattice SU(2) gauge-scalar model with a single scalar field in the fundamental representation of the gauge group, we have quite recently found that there exists a gauge-independent transition line separating Confinement phase and Higgs phase without contradicting the well-known Osterwalder-Seiler-Fradkin-Shenker analyticity theorem between the two phases by performing numerical simulations without any gauge fixing [Phys.Rev.D109, 054505 (2024)]. This was achieved by examining the correlation between the original fundamental scalar field and the so-called color-direction field constructed from the gauge field through the gauge-covariant decomposition due originally to Cho-Duan-Ge-Shabanov and Faddeev-Niemi.
In this talk, we give further numerical evidences for the gauge-independent separation between Confinement phase and Higgs phase in the above model to establish its physical origin. For this purpose, we measure the string tension (the Wilson loop average) and the gauge boson mass (the gauge field correlator) across the new transition line. Moreover, we investigate the contributions from magnetic monopoles to determine their role in confinement and mass generation (mass gap) from the viewpoint of the electric-magnetic duality.
I discuss the symmetry and the physics which distinguishes the confinement and Higgs phases of a gauge-Higgs theory, and the possible existence of unexpected particle excitations in the Higgs phase.
After briefly reviewing the axion solution to the strong CP problem, I will discuss recent new alternative ideas based on CP as part of a spontaneously broken flavour symmetry such as modular invariance.
I will discuss recent applications of functional methods, in particular the combination of Dyson-Schwinger and Bethe-Salpeter equations, to hadron spectroscopy. There are various ongoing efforts in investigating the properties of exotic hadrons and multiquark states such as tetraquarks, pentaquarks and hexaquarks. Here I will mainly focus on four-quark states in the heavy-light sector and present first results on six-quark states such as the deuteron. Progress towards ab-initio calculations of hadron properties will also be highlighted.
Beta decays offer an opportunity for low-energy precision tests of the Standard Model, in particular, checking the unitarity of the first-row CKM matrix which connects the weak and QCD flavor bases. These tests require a combination of the experimental measurements, effective field theory and phenomenology, as well as lattice QCD for non-perturbative input. State of the art theory predictions require an understanding of radiative QED corrections at the 1e-4 level of precision. There is presently a ~3 sigma tension in first-row unitarity with exciting prospects to improve the experimental and theoretical inputs. I will describe some theoretical advances with am emphasis on lattice QCD contributions.
J-PARC, Japan Proton Accelerator Research Complex, is located in Ibaraki, Japan. It is capable of providing a high-intensity proton beam of up to 30 GeV. A broad nuclear and particle physics program is conducted at J-PARC's Hadron Experimental Facility to study matter in extreme conditions, understand the origin and structure of hadrons, and search for physics beyond the standard model. This includes hypernuclear and hadron spectroscopy, hyperon scattering experiments, studies of exotic meson-nucleus systems, and searches for CP-violating rare kaon decays. In this talk, I will focus on research activities at the Hadron Experimental Facility. It accepts a slowly extracted 30 GeV proton beam from the J-PARC Main Ring and provides either directly the primary proton beam or secondary beams such as pions and kaons to its experimental areas. I will review the outcomes of the experiments and discuss some of the current and future physics programs. I will include one of my recent activities, which involves dielectron measurement in p+A collisions at J-PARC, which aims to study the spectral change of vector mesons in a nuclear medium.
Almost twenty years ago, physicists at at Brookhaven National Laboratory measured the magnetic moment of the muon with a remarkable precision of 0.54 parts per million. Since that time, the reference Standard Model prediction for this quantity has exhibited a persistent discrepancy with experiment of more than three sigma. This raises the tantalizing possibility of undiscovered forces or elementary particles.
The attention of the world was drawn to this discrepancy in 2021 when physicists at Fermilab presented the first results of a new experimental measurement, brilliantly confirming Brookhaven's measurement and bringing the discrepancy to a near discovery level of 4.2 sigma. This discrepancy was further enhanced to 5.1 sigma in 2023 with Fermilab’s latest result, which reduces the measurement uncertainty by a factor of 2. However, in the meantime, new tensions have emerged between different determinations of the hadronic vacuum polarisation (HVP) contribution to the theoretical result.
In this plenary I will review the current status of theoretical determinations of the muon anomalous magnetic moment in the context of the latest experimental results. I will particularly focus on our evolving understanding of the HVP, and what this means for the possibility of new physics in this longstanding discrepancy.
In recent years, rapid progress has been made on the determination of PDFs and others from Lattice QCD. Very promising results are obtained while there are still some open questions that need to be discussed. New perspectives are also required, and we hope through this round table discussion, new thoughts can be inspired.
High-order perturbative calculations are one of the only first-principles ways of studying the behaviour of QCD matter at extreme densities. Understanding such matter has become increasingly important in recent years, with the improved experimental access to neutron stars --- the only known systems where deconfined dense matter exists --- via both improved measurements of lonely neutron stars as well as the advent of gravitational wave astronomy, with which collisions involving neutron stars can be observed.
The most fundamental quantity in thermal field theory is the energy density governing the equation of state of matter, from which other equilibrium properties can be derived. I will explain how a diagrammatic perturbative expansion of this quantity is constructed in dense QCD. This will include contributions from low-energy gluons sI will discuss a perturbative evaluation of the adjoint chromoelectric correlator in euclidean space as well as the related transport coefficients. With modern thermal IBP methods for handling the relevant loop integrals, the computation can be automated and the integrals reduced to a far simpler form than those encountered in the past. For the adjoint correlators, this method also allows one to track down the source of an asymmetry of the correlator in the euclidean space, observed in lattice simulations, in a pertubative calculation.creened by the medium as a key ingredient of proceeding past classic results from the 1970s. A description of these "soft" gluons in terms of Hard Thermal Loops, extended to two-loop order, has been the key missing ingredient in high-order computations. I will discuss recent N3LO results up to and including O(g⁶log(g)), now matching those obtained at high temperatures, and including all contributions involving soft gluons.
Understanding the thermodynamics of cold and dense QCD matter has become a prominent research topic due to recent advances in neutron-star observations. Unfortunately, the notorious Sign Problem impedes the study of such matter using lattice QCD.
However, nonperturbative inequalities constrain the pressure of dense QCD with its phase-quenched counterpart, a Sign-Problem-free theory that is amenable to lattice treatment. In the perturbative regime, characterized by a small QCD coupling constant g, one of these inequalities manifests as an O(g⁶) difference between the phase-quenched and full QCD pressures at large baryon chemical potential.
In this talk, I will introduce the finite-density generalization of the loop-tree-duality, a powerful algorithmic technique from vacuum quantum field theory used for numerically tackling high-order diagrammatic computations. Using this approach, we have evaluated the O(g⁶) difference, demonstrating that it is a gauge-independent, small positive number relative to the known perturbative coefficients at this order. This finding suggests that phase-quenched lattice simulations can serve as a complementary nonperturbative method for accurately determining the pressure of cold and dense quark matter at O(g⁶).
Due to its phenomenological relevance in heavy-ion collisions, cosmology and astrophysics, the determination of the QCD pressure - either at high temperature or large baryon density - has driven a number of important theoretical advances in perturbative thermal field theory applicable to equilibrium thermodynamics. In particular, the long-standing infrared problems that obstruct the perturbative series have been overcome by a systematic use of dimensionally reduced effective theories at high temperatures, and hard thermal loops at large baryon density. This allows mapping the problem of determining the full next-to-next-to-next-to-leading-order (N3LO) pressure to a challenging four-loop computation in thermal QCD. In this talk, we present advances in organizing this formidable calculation both in the hot Yang-Mills sector and for cold and dense quark matter. By classifying the distinct contributions, we filter out a large fraction of sub-diagrams that exhibit a factorized structure, and push ahead systematic simplifications taking into account linear relations that originate from the graphs' internal symmetries. This will enable us to gauge the grade of difficulty of a full determination of the pressure of QCD at N3LO in two phenomenologically interesting regimes, serving as the first steps toward the automation of large-scale perturbative computations in thermal field theory.
We investigate spectral features of bottomonium at high temperature, in particular the thermal mass shift and width of ground state S-wave and P-wave state. We employ and compare a range of methods for determining these features from lattice NRQCD correlators, including direct correlator analyses, smeared spectral functions, and Bayesian methods for spectral function reconstruction. We comment on the reliability and limitations of the various methods.
The status of narrow states in heavy quark systems is discussed. For states with only heavy valence quarks these are generally states without Zweig allowed decays. The special case of the X(3872) is reexamined in light of new measurements.
For systems with heavy quarks plus light degrees of freedom three systems are discussed: (1) The j=1/2 1P states of heavy-light mesons, (2) The stability of some ground state tetraquark systems, (3) For doubly heavy baryons (ccs, cbs, bbs) the lowest 1P states will be narrow.
We present results for dipion transitions between heavy quarkonium states of large principal quantum number for which the multipole expansion does not hold. We combine the QCD effective string theory with the Chiral Lagrangian in order to get the appropriate vertexes. We extend the results to transitions for which the initial estate is a heavy quarkonium hybrid. We observe that the dipion spectrum is qualitatively different if the initial state is a hybrid or a quarkonium.
We study the light and heavy quark mass dependence of the low-lying charmed mesons in the framework of one-loop HHχPT. The low energy constants are determined by analyzing the available lattice data from different LQCD simulations. Model selection tools are implemented to determine the relevant parameters as required by data with a higher precision. Discretization and other effects due to the charm quark mass setting are discussed. We also show how this study can be used for studying the quark mass dependence of exotic states, connected to their molecular nature. In particular, we show several results from analyses of LQCD data for the Ds0(2317) and Ds1(2460).
I will discuss recent progress in heavy quarkonium calculations from lattice QCD. Fully relativistic QCD on fine lattices -- with physical light and heavy quark masses, and realistic sea quark content -- allows precise determination of a number of charmonium and bottomonium properties such as meson masses and decay constants, which provide stringent tests of the strong interaction. Meson masses can subsequently be used to tune and make accurate determinations of quark masses from lattice QCD, while the decay constants can allow, in conjunction with annihilation rates from experiment, calculations of CKM matrix elements. I will discuss these and other important highlights from recent lattice QCD calculations including precise determinations of decay rates, comparing them to results from experiment.
Pseudoscalar mesons are the simplest quark-antiquark bound states. Understanding their internal structure is at least as important in comprehending the working of quantum chromodynamics as hydrogen atom was for understanding quantum electrodynamics. The Q^2 evolution of their electromagnetic and two-photon transition form factors from Q^2 -> 0 to its asymptotically large values helps us explore the infrared and ultraviolet behavior of quantum chromodynamics within one single observable. Schwinger-Dyson equations (SDEs) provide an ideal framework to study the fundamental internal degrees of a meson, i.e., quarks and gluons, as their derivation and structure requires no recourse to the coupling strength being small or large. Mesons being two-body bound states also require a relativistic Bethe-Salpeter equation (BSE) to study their internal structure. We adopt a coupled SDE/BSE based formalism to investigate light pseudoscalar meson form factors, making comparison with the experimental results whenever available and also discussing their implications for the tests of the Standard Model of particle physics.
Baryon spectroscopy gives insights into the dynamics between the constituents of baryons and study quantum chromodynamics (QCD) in the non-perturbative regime. Quark models and Lattice calculations predict a large number of baryons, but only a fraction of them have been found experimentally.
The baryon spectra can be probed with a real photon beam by studying various different photoproduction reactions. Partial-wave analyses need to be performed to extract the baryon resonance parameters from the experimental data. For an unambiguous solution, several single and carefully chosen double polarization observables are needed in addition to the unpolarized cross section.
Worldwide, various experimental facilities have dedicated programs to measure these polarization observables in different photoproduction reactions using polarized photon beams and polarized targets. Two of the leading experimental facilities are located in Germany, the CBELSA/TAPS experiment at the accelerator facility ELSA in Bonn and the Crystal Ball experiment at the accelerator facility MAMI in Mainz. Both experiments are excellent at measuring neutral mesons in the final states, using electromagnetic calorimeters covering almost the full angular range, while exploring complementary beam energy regions. This talk will give an overview about recent results in non-strange baryon spectroscopy at ELSA and MAMI.
While the excitation spectrum of light mesons, which are composed of up and down quarks, is already mapped out fairly well, the spectrum of strange mesons is still to be mapped out in detail, potentially holding many surprise.
At the COMPASS experiment at CERN, we study the strange-meson spectrum in the diffractive scattering of a high-energy kaon beam.
In this talk we will focus on the $K^-\pi^-\pi^+$ final state, for which COMPASS has acquired the world's largest data set to date.
Based on this data set, we have performed a partial-wave analysis to disentangle the produced mesons by their spin-parity quantum numbers and to measure their masses and widths.
We will report on recent results from this analysis, including the search for an exotic strange mesons, and we will give prospects for a high-precision measurement of the strange-meson spectrum at AMBER -- a new QCD facility at CERN.
Computing the parton distribution functions (PDFs) of hadrons from lattice QCD poses well known challenges due to the theory being formulated on discrete Euclidean spacetime. For example, power divergent mixing due to the reduced symmetry of the lattice theory precludes obtaining Mellin moments of PDFs starting at <x^4> or higher, and requires the use of boosted states with poor signal-to-noise properties for <x^2> and <x^3>. In this work, we implement and test a recent proposal [1] to use gradient flow to circumvent the power divergent mixing problem. We present preliminary results on the first few moments of the unpolarized flavor non-singlet PDF of the pion in the MSbar scheme, using ensembles at the SU(3) flavor symmetric point, generated with stabilized Wilson fermions by the OpenLat Initiative.
[1] Moments of parton distribution functions of any order from lattice QCD, Andrea Shindler, arXiv:2311.18704
Duality between quarks and baryons is the fundamental properties of QCD. We have recently shown in Ref. [1] that the duality is closely tied to Quarkyonic nature of matter at high baryon density. We have formulated a dual model for dense QCD, which allows a thermodynamic description both in terms of baryons or quarks, with the quark confinement relation that sets the transformation between both descriptions.
The nontrivial robust consequence of the duality is that when we persist with the baryonic picture in the region where the quark description is more natural, the shell structure, which is the notable feature of Quarkyonic matter, appears in the pure baryonic distribution owing to the Pauli exclusions among quarks. This Quarkyonic shell structure is dual to a description in terms of quarks with a filled Fermi sea of quarks with a finite Fermi surface.
In this talk, we discuss the implication of this Quarkyonic duality to the hyperon puzzle [2]. We illustrate the combined effect of the duality and the strangeness by extending the model to three flavors. We find that the threshold density for the hyperons are shifted to higher density compared to the conventional treatment, and the softening of the equation of state becomes milder.
References:
[1] Y. Fujimoto, T. Kojo, L. McLerran, Phys. Rev. Lett. 132, 112701 (2024), [2306.04304].
[2] Y. Fujimoto, T. Kojo, L. McLerran, In preparation.
We investigate the effects of rotation on deconfinement and chiral phase transitions in the framework of dynamical holographic QCD model. Instead of transforming to the rotating system by Lorentz boost, we construct an anisotropic gravitational background by incorporating the rotating boundary current. We firstly investigate the pure gluon system under rotation to extract deconfinement phase transition from the Polyakov loop then add 2-flavor probe for chiral restoration phase transition from the chiral condensate. It is observed that at low chemical potentials, the deconfinement phase transition of pure gluon system is of first order and the chiral phase transition of 2-flavor system is of crossover. Both the critical temperatures of deconfinement and chiral phase transitions decrease/increase with imaginary/real angular velocity ($\Omega_I/\Omega$) as $T/T_c\sim 1- C_2 \Omega_I^2$ and $T/T_c\sim 1+ C_2 \Omega^2$, which is consistent with lattice QCD results. In the temperature-chemical potential $T-\mu$ phase diagram, the critical end point (CEP) moves towards regions of higher temperature and chemical potential with real angular velocity.
Recently, we conducted a kaonic nuclear-bound state search experiment using a K
−
beam
(1 GeV/c) bombarding a 3He target. We succeeded in observing a kaonic nuclear quasi-bound
state,“K−pp”, via a nucleon knockout reaction, K−N → K ̄n′, followed by the decay K ̄NN → Λp
(2NK ̄A) in the two-nucleon K ̄ absorption process, resulting in the final state Λp + n′. The result
−
cay width of about 100 MeV. From the Λp decay, the isospin of the system is determined to be
IK ̄NN = 1/2. The momentum transfer distribution of the Λp system is very broad, implying that
−
decay process of the K ̄NN via one-nucleon K ̄ absorption (1NK ̄A: K ̄N → πY ), and B) by searching
for the K ̄NNN bound state through the Λd invariant mass study of the Λd + n′ final state with
shows that the ”K pp” binding energy is about 40 MeV below the binding threshold, with a de-
the size of the ”K
We extended our study on the kaonic nuclear-bound state in two ways: A) by studying the mesonic
pp” system might be very compact [1, 2].
a K− beam (1 GeV/c) bombarding a 4He target. The aim of A) is to understand why the decay −
width of “K pp” is about twice as broad as that of Λ(1405) (∼ 50 MeV), which is assumed to be
a molecule-like hadronic cluster composed of a K ̄ meson and a nucleon, i.e., Λ(1405) ≡ K ̄N, as
introduced by R.H.Dalitz et.al.[3]. The result shows that the K ̄NN → πYN decay is dominant
(1NK ̄A ≫ 2NK ̄A) and that the πΣN to πΛN ratio is about 1:1, indicating that the IK ̄N = 1 channel
absorption channel is approximately equal to the IK ̄N = 0 channel. The result also suggests that
there is a hint of the ”K ̄0nn” bound state, a charge mirror state of “K−pp”, existing in the π−Λp −′
invariant mass spectrum of the π Λp + p final state.
In the Λd invariant mass study B), the two-dimensional preliminary spectrum of the Λd invari-
ant mass and the momentum transfer to Λd (mΛd,qΛd) shows an almost identical distribution to (mΛp , qΛp ), indicating the presence of K ̄NNN , decaying to Λd. If this is another kaonic nuclear- bound state, then the isospin, spin-parity is fixed to be I(JP ) = 0(1/2−).
In this talk, we’ll describe these two new results on kaonic nuclear-bound states and discuss the prospects of studying the molecule-like hadronic cluster with strangeness.
The enormous density of the nuclear matter at the core of a neutron star (or proto-star) challenges our understanding of the strong interaction. There are convincing arguments that hyperons must play a role, with consequences for the equation of state, the speed of sound and observable properties. It is also possible that confinement breaks down. We will review recent progress on these issues.
Ab initio nuclear structure theory aims to predict the structure of atomic nuclei from "first principles," employing systematically improvable approximations for nuclear forces and many-body wave functions. This ab initio paradigm has been established as a consistent, precise framework for predicting the structure of medium-mass nuclei with the ability to fully quantify uncertainties. In particular, ab initio calculations can give controlled predictions for nuclear structure effects in searches for physics beyond the standard model in atoms and nuclei. Recent developments have extended ab initio calculations on two frontiers: towards higher precision and towards heavier nuclei. These developments allow us to provide fully uncertainty quantified nuclear structure input for a search for a new boson in ytterbium isotope shifts. Based on our input, we identify the leading signal in ytterbium isotope shifts to be due to the structure of ytterbium isotopes, not the new possible boson, and extract new information on higher-order nuclear structure from high-precision mass and frequency measurements. We conclude with an outlook on ongoing studies of nuclear structure effects in neutrinoless double-beta decay and muon-to-electron conversion.
Since the 2017 observation of gravitational wave and electromagnetic signals from a neutron star merger, binary mergers have emerged as a powerful environment in which to study physics beyond the standard model (BSM). As an example of BSM physics, and due to their connection to QCD, I will focus on axions and describe the various roles they may play in neutron star mergers, as well as the prospects for constraining axions with future neutron star merger observations.
FASER, the Forward Search Experiment, at the Large Hadron Collider (LHC) aims to study neutrino interactions with the unexplored high energy range and to search for light, weakly-interacting new particles. The detector is located 480 m downstream of the ATLAS interaction point along the beam axis.
The FASER collaboration announced the first direct observation of collider neutrinos, using the initial data from Run3. The first measurement of the cross-sections of electron neutrino and muon neutrino interactions were made, using a sub-sample of data collected with an emulsion detector. We also searched for dark photons and axion-like particles (ALPs), which are strong candidates for light dark matter models, obtaining new constraints on the parameter space.
In this seminar, the first physics results from FASER will be discussed. Additionally, future plans for the Forward Physics Facility (FPF), which will provide important insights into QCD, will be introduced.
The Belle II experiment at the SuperKEKB energy-asymmetric e+e− collider is a substantial upgrade of the B factory facility at the KEK laboratory. Belle II will be able to measure the Cabibbo-Kobayashi-Maskawa (CKM) matrix, the matrix elements and their phases, with unprecedented precision and explore flavor physics with B, charmed mesons, and τ leptons. We report on recent results obtained by the Belle II experiment related to searches for beyond-the-standard-model physics.
Superinsulators are a new topological state of matter, predicted by our collaboration and experimentally observed in the critical vicinity of the superconductor-insulator transition (SIT). Superinsulators are dual to supercon- ductors and realise electric-magnetic (S) duality. In superinsulators ,Cooper pairs are linearly bound by electric fields squeezed into strings (dual Meissner effect) by a monopole condensate (instantons plasma in (2+1) dimensions), in analogy to quarks in hadrons. Superinsulators realise, thus, the electric version of the dual superconductor mechanism proposed to explain confinement in QCD.
When Anderson localization entered the QCD landscape, it was almost immediately thought about in connection with thermal phases, namely as a factor in the chiral phase transition or crossover. However, developments over the last three years revealed an additional structure that made Anderson-like features central to the genesis and understanding of the new thermal phase: the IR phase of QCD. I will explain these developments.
I present a new way of understanding how chiral symmetry is realized in the
high temperature phase of QCD. I show that a simple instanton-based random
matrix model provides an excellent description of the lowest part of the
spectrum of the lattice overlap Dirac operator. Even though dynamical quarks
introduce instanton-antiinstanton interactions, the lowest part of the
spectrum, dominating physical quantities related to chiral symmetry, can be
understood in terms of a non-interacting instanton gas that turns out to
generate a spectral density singular at the origin. Besides providing an
intuitive physical picture of how light quarks interact with gluons at high
temperature, the model also has nontrivial quantitative predictions. In
particular, by generalizing the Banks-Casher formula for the singular spectral
density, I show a possible resolution of the long-standing debate about the
fate of the anomalous U(1)_A symmetry above the critical temperature.
We discuss the properties of Quantum Chromodynamics obtained by means of lattice simulations with the overlap fermion discretisation. This fermion discretization preserves chiral symmetry even at finite lattice spacing. We present the details of the formulation, results for the chiral observables and discuss the (chiral) properties of finite temperature QCD around the phase transition.
We deepen the understanding of the primordial composition of the Universe in the temperature range $130\,\mathrm{GeV}>T>0.02\,\mathrm{MeV}$ within the big-bang FLWR cosmology model by applying the know-how of the Standard Model (SM) of particle physic. In this temperature range the unknown cold dark matter and dark energy have a negligible influence allowing a reliable understanding of physical properties of the SM Universe. SM elementary particles were abundantly present as the hot primordial Universe expanded and cooled. We study the abundance of SM particles initially dominated by strongly coupled SM heavies (t, H, W, Z) present in the hot primordial plasma in search for periods of long-lasting abundance (chemical) non-equilibrium of great relevance to baryogenesis processes. After SM heavies diminish in abundance below $T\simeq 50$\,GeV, the SM plasma the Universe properties are governed by the strongly interacting Quark-Gluon content. Once the temperature drops below $T\simeq 150$\,MeV Quarks and gluons hadronize into strongly interacting matter particles. Rapid disappearance of baryonic antimatter ensues which completes near $T=38.2$\,MeV in a Universe with the present day photon to baryon ratio. Near $T=\mathcal{O}(2)$\,MeV we explore the emergence of the free-streaming neutrino era, and develop methods allowing to study the ensuing speed of the Universe expansion as a function of SM parameter primordial values which could differ from the present day measurement. We subsequently follow the early Universe as it passes through the hot dense electron-positron plasma epoch and we analyze the paramagnetic characteristics of the electron-positron plasma when exposed to an external primordial magnetic field. The high density of positron antimatter disappears near $T=20.3$\,keV, well after the Big Bang nucleosynthesis era. This requires reconsideration of nuclear reactions in the presence of a highly mobile electron-positron plasma phase. We apply plasma theory methods to describe the strong screening effects associated with polarization of the highly mobile electron-positron plasma phase.
Machine learning technologies has gained a great advance to affect various fields of research in physics, and nonperturbative QCD is not an exception. Here in this talk I will rephrase the AdS/CFT correspondence by a deep learning architecture, and demonstrate the emergence of the gravity geometry by using QCD data, thus establishing a possible duality between QCD and a gravitational theory. This solves the inverse problem of the AdS/CFT, in other words, it is a QFT-driven holographic modeling. The lattice data of the chiral condensate is used to train a neural network to make a bulk gravity model, and the model can predict Wilson loop expectation values, to be well compared with the lattice Wilson loop results.
QCD instantons are arguably the best motivated yet unobserved nonperturbative effects predicted by the Standard Model. A discovery and detailed study of instanton-generated processes at colliders would provide a new window into the phenomenological exploration of QCD and a vastly improved fundamental understanding of its non-perturbative dynamics. We review a recent calculation of QCD instanton-induced processes in proton-proton collisions accounting for quantum corrections due to both initial and final state gluon interactions. Although QCD instanton processes are predicted to be produced with a large scattering cross-section at small centre-of-mass partonic energies, discovering them at hadron colliders is a challenging task that requires dedicated search strategies.
Basis light-front quantization (BLFQ) is a fully relativistic and nonperturbative method based on a light-front quantized Hamiltonian with input from Quantum Chromodynamics (QCD), offering the potential for first-principle calculations. In our QCD applications, we incorporate a form of confinement derived from light-front holography and additional longitudinal confinement into the Hamiltonian. This approach ensures that BLFQ results align with both global fitting and experimental data for various hadronic properties. Recent progress includes expanding Fock spaces to include five-particle sectors, such as the five-quark and three-quark-two-gluon sectors, and incorporating relevant QCD interactions to replace the effective confining potential. By utilizing the light-front wave functions generated by BLFQ, we compute observables such as parton distribution functions (PDFs) of gluons and sea quarks at low-resolution scales and evolve them to higher scales in line with QCD, enabling comparison with experimental extractions. In conclusion, I will also discuss potential directions for future advancements.
I will review the latest fluctuation measurements of strangeness, charge and baryon number from LHC and RHIC, with a focus on results from the second beam energy scan at RHIC. I will confront the data with lattice QCD calculations at zero and small baryon densities and with phenomenological and holographic models at finite baryon densities.
Exploration of the QCD phase diagram is pivotal in particle and nuclear physics. We construct a full four-dimensional equation of state of QCD as a function of the temperature and the chemical potentials of baryon (B), charge (Q), and strangeness (S) by extending the NEOS model [1] beyond the conventional two-dimensional approximation. Lattice QCD calculations based on the Taylor expansion method [2] and the hadron resonance gas model are considered for the construction. We also develop an efficient numerical method for the application of the four-dimensional equation of state to relativistic hydrodynamic simulations, which can be used for the analyses of the nuclear collisions at beam energy scan energies and of different nuclear species at the BNL Relativistic Heavy Ion Collider.
[1] A. Monnai, B. Schenke, and C. Shen, Phys. Rev. C 100, 024907 (2019); Int. J. Mod. Phys. A 36, 2130007 (2021)
[2] A. Bazavov et al., Phys. Rev. D 90, 094503 (2014); H.-T. Ding et al., Phys. Rev. D 92, 074043 (2015); A. Bazavov et al., Phys. Rev. D 95, 054504 (2017)
We develop the (3+1)D dilute Glasma approximation [1], a semi-analytic framework for the computation of rapidity-dependent early-time observables in relativistic proton and ion collisions. Going beyond the boost-invariant approximation, we take the three-dimensional distribution of color charges within nucleons and nuclei into account. Specifically, we find a simple analytic expression for the Yang-Mills field strength tensor of the Glasma. In contrast to classical lattice simulations, our approach allows for the efficient computation of energy and momentum densities of the Glasma using Monte Carlo integration. In this contribution, I present our study of proton collisions considering different models with and without individual quark hot spots and allowing for fluctuations in the saturation momentum. The obtained energy density is mapped to charged-particle multiplicity and compared to experimental data in order to constrain the model parameters. This paves the way for future (3+1)D simulations of pA- and AA-collisions in the dilute Glasma framework.
[1] Ipp, A., Leuthner, M., Müller, D. I., Schlichting, S., Schmidt, K., & Singh, P.
Energy-momentum tensor of the dilute (3+1)D Glasma [2401.10320]
The dilute Glasma is a novel approach to modeling the rapidity-dependent initial stage of ultra-relativistic heavy-ion collisions based on the Color Glass Condensate effective field theory. The gluonic interaction between the large Bjorken-x, static sources localized in the colliding nuclei is described by classical Yang-Mills equations. By performing an expansion in the weak sources, we are able to obtain remarkably simple, analytic solutions for the Glasma field strength tensor and evaluate them via Monte-Carlo integration. Within this setup, we employ a generalized McLerran-Venugopalan nuclear model with parametrized longitudinal correlations and study Pb+Pb collisions at LHC and Au+Au collisions at RHIC energies. In particular, we recover limiting fragmentation on the level of the energy-momentum tensor at RHIC and predict it to hold for LHC energies as well. In this contribution, I will compare this prediction to other initial state models and assess its compatibility with experimental data. I will also give an outlook for our analytic proof of the limiting fragmentation behavior and discuss that it is a generic feature of the dilute Glasma expansion.
[1] Ipp, A., Leuthner, M., Müller, D. I., Schlichting, S., Schmidt, K., & Singh, P.
Energy-momentum tensor of the dilute (3+1)D Glasma. [2401.10320]
Using a quark model with parameters that well reproduce the ground state hadron masses, we discuss what configurations are attractive and contribute to exotic configurations. We then discuss how these configurations conspire to enhance production of certain particles in heavy ion collisions when quark-gluon plasma is formed. As an illustration, we discuss recent observations of $\Xi_c/D$ enhancement in high multiplicity high-energy proton-proton or ultrarelativistic heavy-ion collisions (Ref: PLB851 (2024) 138569).
We resum the double logarithmic singularities at threshold in heavy quarkonium fragmentation functions based on the nonrelativistic QCD factorization formalism. At fixed order, we reproduce the double logarithmic singularities known at next-to-leading order accuracy. Unlike fixed-order calculations, the resummed fragmentation functions we obtain are smooth functions that no longer contain singularities at threshold. We also discuss phenomenological applications including inclusive production at large transverse momentum.
It was found that, using nonrelativistic QCD factorization, the predicted $\chi_{cJ}$ hadroproduction cross section at large $p_T$ can be negative. The negative cross sections originate from terms proportional to plus function in $^3P_{J}^{[1]}$ channels, which are remnants of the infrared subtraction in matching the $^3P_{J}^{[1]}$ short-distance coefficients. In this article, we find that the above terms can be factorized into the nonperturbative $^3S_{1}^{[8]}$ soft gluon distribution function in the soft gluon factorization (SGF) framework. Therefore, the problem can be naturally resolved in SGF. With an appropriate choice of nonperturbative parameters, the SGF can indeed give positive predictions for $\chi_{cJ}$ production rates within the whole $p_T$ region. The production of $\psi(2S)$ is also discussed, and there is no negative cross section problem.
The production of particles containing heavy quarks (beauty and charm) from proton and heavy ion collisions is extensively studied at the LHCb (Large Hadron Collider beauty) experiment. Studying the effect of multiplicity on the production of particles containing heavy quarks, probes the production mechanism of such particles.
The LHCb experiment is unique in its ability to observe particles containing heavy quarks in the 'forward' region (2 < η < 5), complementing observations in central pseudo-rapidity regions found in the barrel spectrometer experiments (ATLAS, CMS and ALICE) at the LHC.
Through the use of tools like RIVET, the LHCb experiment can coordinate with theorists to further refine and validate event generators using experimental data from such analyses.
In this talk, we will present results from the latest measurements of heavy flavour production performed by the LHCb experiment, pointing out areas where there is scope for improvements in event generators.
The study of CP violation is critical for understanding the asymmetry between matter and antimatter in the universe. This talk presents the CP violation in $B_s^0 \to J/\psi\,\phi$ decays measured with the CMS detector at the LHC using Run 2 data. A full angular analysis of the decay is performed, extracting several key parameters such as the CP-violating phase, the amount of direct CP violation and differences in decay width and mass between mass eigenstates. The study employs an innovative flavour tagging approach, leveraging machine learning to improve accuracy by using information from both sides of the decay.
This talk present the study on the next-to-next-to-leading-order (NNLO) QCD corrections to $e^+e^- \to J/\psi+\eta_c$ and $e^+e^- \to J/\psi+J/\psi$ at the $B$ factories, based on our two published work :
JHEP 02 (2024) 055e-Print: 2311.04751 [hep-ph], and JHEP 02 (2023) 049, e-Print: 2212.03631 [hep-ph].
For $e^+e^- \to J/\psi+\eta_c$ is enhanced by about $17\%$, and the perturbative series of the prediction shows the convergent behavior. It is also found that the contributions from bottom quark starts at the $\alpha_s^3$-order, which is about $2.4\%$ of the total prediction. The renormalization scale $\mu_R$ dependence of the cross section is reduced at the NNLO level, but the prediction is sensitive to the charm quark mass $m_c$. By considering the uncertainties caused by renormalization scale $\mu_R$, charm quark mass $m_c$ and the NRQCD factorization scale $\mu_\Lambda$, our prediction shows agreement with the BBAR and BELLE measurements within errors
For $e^+e^- \to J/\psi+J/\psi$, to obtain a reasonable estimation for the cross section, the square of the amplitude up to NNLO is used, and the result for total cross section and differential cross section could be compared with precise experimental measurement in future at the B factory.
In this talk, I will present our latest theoretical results regarding the exclusive double J/psi production at the B factory.
I will elucidate the reasons why the conventional NRQCD-based predictions for this process exhibit a notably poor convergence. I will then demonstrate that this convergence can be significantly enhanced by employing an improved NRQCD factorization approach. I will also present our most precise predictions, accurate up to NNLO QCD corrections, and discuss the detection prospects for this process.
The self-interacting nature of gluons remains one of the most fascinating characters of QCD. An observation of glueball states will be the ultimate validation of low energy QCD. The radiative decay of the $J/\psi$ meson is a gluon-rich process and is therefore regarded as an ideal place for searching and studying glueballs.
Based on $(10087\pm44)\times10^{6}$ $J/\psi$ events collected with the BESIII detector, a partial wave analysis of the decay of $J/\psi\rightarrow\gamma K^{0}_{S}K^{0}_{S}\eta'$ is performed and spin-parity of the X(2370) is determined for the first time to be $0^{-+}$ [PRL.132.181901(2024)]. Besides that, the mass and width of the X(2370) are measured, as well as the corresponding product branching fraction $\mathcal{B}[J/\psi\rightarrow\gamma X(2370)] \times \mathcal{B}[X(2370) \rightarrow f_{0}(980)\eta'] \times \mathcal{B}[f_{0}(980) \rightarrow K^{0}_{S}K^{0}_{S}]$. The measured properties of $X(2370)$ are consistent with the predictions of the pseudoscalar glueball candidate by lattice QCD calculation. In addition, recent results on the psedoscalar spectroscopy from BESIII will also be presented, including J/psi->gamma KKpi [JHEP 03, 121 (2023)]and Jpsi->gamma gamma phi[arXiv:2401.00918].
We present the first observation of the rare η→μ^+ μ^- μ^+ μ^- double-Dalitz decay. The analysis is based on data collected by the CMS experiment at the CERN LHC operating at the centre-of-mass energy of √s=13 TeV. The data sample was collected with high-rate muon triggers for an integrated luminosity of 101 fb^(-1).
The branching fraction of the η→4μ decay is measured relative to the η→2μ decay yielding a value of B(η→μ^+ μ^- μ^+ μ^- )=[5.0±0.8(stat)±0.7(syst)±0.7(B_2μ )]×10^(-9), in agreement with the Standard Model theoretical predictions.
We explore the distribution of the Lee-Yang zeros around the critical point that appears in the heavy-quark region of QCD at nonzero temperature in lattice numerical simulations. With the aid of the hopping-parameter expansion that is well justified around the critical point in our setting, our numerical analysis is capable of analyzing the partition function in the complex parameter plain with high accuracy. This enables precise analyses of the Lee-Yang zeros around the critical point. We study their finite-size scaling around the critical point. We also propose new methods to utilize the scaling behavior of the Lee-Yang zeros to fix the location of the critical point and edge singularity.
In this talk, I will introduce a novel framework proposed to extract near-threshold resonant states from finite-volume energy levels of lattice QCD and is applied to elucidate structures of the positive parity $D_s$. The quark model, the quark-pair-creation mechanism and $D^{(*)}K$ interaction are incorporated into the Hamiltonian effective field theory. The bare $1^+$ $c\bar s$ states are almost purely given by the states with heavy-quark spin bases. The physical $D^*_{s0}(2317)$ and $D^*_{s1}(2460)$ are the mixtures of bare $c \bar s$ core and $D^{(*)}K$ component, while the $D^*_{s1}(2536)$ and $D^*_{s2}(2573)$ are almost dominated by bare $c\bar{s}$. Furthermore, our model well reproduce the clear level crossing of the $D^*_{s1}(2536)$ with the scattering state at a finite volume. The same framework has also been extended to study the the positive parity $B_s$ states.
Using the world’s largest samples of J/psi and psi(3686) events produced in e+e- annihilation, BESIII is uniquely positioned to study light hadrons in radiative and hadronic charmonium decays. In particular, exotic hadron candidates including multiquark states, hybrid mesons and glueballs can be studied in high detail. Recent highlights on the light exotics searches, including observation of an iso-scalar spin-exotic 1-+ state η1(1855) in J/ψ→γηη′, observation of X(2600) in J/ψ→γπ+π-η′, observation of the anomalous shape of X(1840) J/ψ→γ3(π+π-), and amplitude analysis of J/ψ→γγphi will be presented.
A unified set of predictions for pion and kaon elastic electromagnetic and gravitational form factors is obtained using a symmetry-preserving truncation of each relevant quantum field equation. A key part of the study is a description of salient aspects of the dressed graviton + quark vertices. The calculations reveal that each meson’s mass radius is smaller than its charge radius, matching available empirical inferences; and meson core pressures are commensurate with those in neutron stars. The analysis described herein paves the way for a direct calculation of nucleon gravitational form factors.
We present a talk on recent investigations of the gravitational form factors (GFFs) and relevant mechanical structure of the nucleon, focusing also on the flavor components of the GFFs. We employ a pion mean-field approach, grounded in the large Nc limit of Quantum Chromodynamics (QCD). We mainly consider the contributions from the twist-2 operators to the flavor-triplet and octet GFFs. We perform the flavor decomposition of the mass, angular momentum, and D-term form factors of the nucleon. We find that the strange quark contributions are found to be mild for the mass and angular momentum of the nucleon while providing significant corrections to the D-term form factor. We discuss a significant contribution from the effects of twist-4 operators. The gluonic contributions are suppressed by the packing fraction of the instanton vacuum in the twist-2 case, but those from twist-4 operators are of order unity, so its explicit consideration is required.
In this work, we study the generalized transverse momentum dependent distribution (GTMD) $E_{21}^{\nu}(x, p_{\perp},\Delta_{\perp},\theta)$ for proton using light-front quark-diquark (LFQDM) model. We construct the $E_{21}^{\nu}(x, p_{\perp},\Delta_{\perp},\theta)$ GTMD using the GTMD overlap equation in light-front wave functions obtained from the GTMD correlator with Dirac matrix structure $\Gamma=1$, in both situations of scalar and vector diquark. Taking two variables at a time while holding the other variables constant, the $3$-dimensional plots obtained from $E_{21}^{\nu}(x, p_{\perp},\Delta_{\perp},\theta)$ GTMD have been analyzed.
The electromagnetic structure of hadrons can be determined by evaluating the scattering of light off the system, provided by the Compton amplitude. Such an evaluation is infeasible mathematically at low energies due to the non-perturbative nature of QCD. Lattice QCD provides a way to numerically determine these structures using a path-integral approach. To produce results in a feasible amount of time the computation is sped up by utilising heavier than physical quark masses. Utilising these methods can provide insight into the electromagnetic structure of any hadron of interest. The Feynman-Hellmann technique is utilised to effectively reduce such an evaluation from that of a four-point correlation function down to a simpler two-point correlation function. While previous work has been done in determining the Compton amplitude of the nucleon, the less explored pion presents a particularly difficult case to evaluate. The lighter mass of the pion makes it more susceptible to noise when evaluating boosted correlation functions of the system. I present preliminary results for the Compton amplitude of the pion at a fixed photon momentum. Additionally, I will discuss ongoing research into the applications of All-Mode Averaging (AMA) as a noise reduction technique to improve these results for further analysis.
Strong magnetic fields impact quantum chromodynamics properties in several situations; examples of situations include the early universe, magnetars, and heavy-ion collisions. All of these examples involve time evolution. In this presentation, I will first present results of a study of the effects of a strong magnetic field on the time evolution of the quark condensate (scalar density) at finite temperature and baryon density within the linear sigma model. The closed-time path (CTP) formalism of nonequilibrium quantum field theory is used to address time evolution and obtain a Langevin equation for the condensate. I will present results of solutions of the derived Langevin equation using values of temperature and magnetic field relevant for different situations. Next, I will present an extension of the CTP formalism to address quark percolation in nuclear matter at high baryon density within a relativistic effective field theory approach. I will then present first results obtained with the formalism on the effects of quark percolation on the scalar density of (magnetized) nuclear matter.
We present a novel resonant spectroscopy technique devoted to the study of gravitation and the related cosmological problems of Dark Matter and Dark Energy. The object is a quantum mechanical wavepacket of an ultra-cold neutron, and the new method extends the techniques of Purcel, Rabi and Ramsey to neutron quantum states in the gravity potential of the Earth. The new technique is named Gravity Resonance Spectroscopy (GRS) in close analogy to Magnetic Resonance Spectroscopy (MRS). Here a neutron in the gravity potential of the Earth is placed on a reflecting mirror, and transitions between the gravitational quantum states are performed by applying mechanical oscillations of the mirror with the proper transition frequency, whereas in MRS technique, an atom, a molecule or a nucleus with a magnetic moment is placed in an outer magnetic field and transitions between the magnetic Zeeman splitting are performed by applying proper oscillations of radiofrequency fields.
We present recent results on the following topics:
First, we analyze the dynamics of ultracold neutrons caused by interactions violating Lorentz invariance within the Standard Model Extension (SME). We use the effective non–relativistic potential for interactions violating Lorentz invariance derived by Kostelecký and Lane (1999) and probe contributions of these interactions to the transition frequencies of transitions between quantum gravitational states of UCNs bouncing in the gravitational field of the Earth.
Second, we analyze a possibility to probe beyond-Riemann gravity by GRS. We improve by order of magnitude some constraints obtained by Kostelecký and Li (2021).
Third Erik Verlinde’s theory of entropic gravity, postulating that gravity is not a fundamental force but rather emerges thermodynamically, has gathered much attention as a possible resolution to the quantum gravity problem. We address some criticism by modelling linear gravity acting on small objects as an open quantum system and show full compatibility with the qBOUNCE experiment.
It is well known that Dark Matter can be captured and accumulate in celestial objects. While this problem and been studied thoroughly for the Sun and the Earth, recently compact celestial objects like White Dwarfs and Neutron Stars have raised the interest of the scientific community. Here I present two recent results related to these objects.
In the case of Neutron Stars, we consider Dark Matter candidates that are allowed to annihilate. The capture of dark matter, and its subsequent annihilation, can heat old, isolated neutron stars. In order for kinetic heating to be achieved, the captured dark matter must undergo sufficient scattering to deposit its kinetic energy in the star. We find that this energy deposit typically occurs quickly, and that capture-annihilation equilibrium, and hence maximal annihilation heating, can be achieved without complete thermalization of the captured dark matter.
For White Dwarfs, we consider the scenario where the Dark Matter is very heavy and cannot annihilate. In the heavy dark matter regime, multiple collisions are required for the dark matter to become gravitationally captured: we present an improved treatment to calculate the multiple scattering rates when the particle interacts with the ion constituents of a white dwarf.
Generalised parton distributions promise to expand our understanding of the behaviour of the elementary quarks and gluons into three dimensions. They provide us with a framework for describing the position of the quarks and gluons as well as how they divide the hadron’s momentum between them. This is an exciting research frontier to be investigated at Jefferson Lab as well as the future Electron-Ion Collider. We use a model for the GPDs to study the cross section for a ground-state nucleon transitioning into a low-energy excited state described as a molecular state, rather than as a simple excitation of a three-quark system. In this way we expect to gain new insight into the makeup of low-lying hadronic resonances.
Including the effects of the chiral anomaly within Chiral Perturbation Theory at finite baryon chemical potential, it has been shown that neutral pions form an inhomogeneous phase dubbed the "Chiral Soliton Lattice" (CSL) above a certain critical magnetic field. Above a second, even higher critical field, the CSL becomes unstable to fluctuations of charged pions, implying they condense. I will point out the similarity of this second critical field to the upper critical magnetic field in conventional type-II superconductors, suggesting that an inhomogeneous superconducting charged pion phase exists beyond this point. Applying similar methods originally used by Abrikosov, I will present results where we've constructed such a phase and show the region where it is preferred in the baryon chemical potential-magnetic field phase diagram at zero temperature. This new phase has a non-zero baryon number density which is periodic in all three spatial dimensions.
The possible link between entanglement and thermalization, and the dynamics of hadronization are addressed by studying the real-time response of the massive Schwinger model coupled to external sources. This setup mimics the production and fragmentation of quark jets, as the Schwinger model and QCD share the properties of confinement and chiral symmetry breaking. By using quantum simulations on classical hardware, we study the entanglement between the produced jets, and observe the growth of the corresponding entanglement entropy in time. This growth arises from the increased number of contributing eigenstates of the reduced density matrix with sufficiently large and close eigenvalues. We also investigate the physical nature of these eigenstates, and find that at early times they correspond to fermionic Fock states. We then observe the transition from these fermionic Fock states to meson-like bound states as a function of time. In other words, we observe how hadronization develops in real time. At late times, the local observables at mid-rapidity (such as the fermion density and the electric field) approach approximately constant values, suggesting the onset of equilibrium and approach to thermalization.
Most of the condensed matter is dominated with models with quasiparticles in the form of Fermi liquid theory. However, physics becomes quite interesting where there is a lack of quasiparticles in the so-called strange metals. We will introduce the physics of non-Fermi liquids in the form of a model without quasiparticles, namely the Sachdev-Ye-Kitaev (SYK) model. We will discuss its various dynamic and thermodynamic properties including charge transport in SYK chains as well as critical exponents for the associated phase transition. Apart from the observed universalities, there might lurk a universality of universalities in the properties of such non-Fermi liquids that we will discuss in the form of critical exponents and quantum chaos characterized using Lyapunov exponents. SYK model has been proposed as a dual to some gravity models and we will discuss the implications of the results for the black holes.
It has been a long-standing problem to study parton showers with important quantum interference effects. In this work, we discuss quantum/classical veto algorithm with kinematical effects incorporated. Our veto algorithm could be of wider use in many other problems of Monte Carlo simulations with quantum interferece effects. This talk is based on Phys. Rev. A 109, 032432 (2024) [arXiv:2310.19881], in collaboration with Christian W. Bauer and So Chigusa.
We present a novel deep learning approach to rebuild the dense matter equation of state (EoS) for probing neutron star observables. By leveraging an automatic differentiation framework, our method solves inverse problems and achieves accurate EoS optimization. Through training a neural network on a comprehensive dataset, we develop a predictive EoS model that yields precise relationships between pressure, speed of sound, and mass density. Our results align with conventional approaches and are consistent with the observed tidal deformability from the gravitational wave event, GW170817.
The BESIII experiment locates at the BEPCII $e^+e^-$ collider in Beijing, China, running in a center-of-mass energy range from 1.84 GeV to 4.95 GeV. After 15 years of successful running of the experiment since 2009, BESIII has accumulated more than 50 fb$^{-1}$ of electron-positron annihilation data, which include 10 billions J/ψ events, 2.7 billions ψ(2S) events, 20 fb$^{-1}$ $D\bar{D}$ samples at ψ(3770) peak and 6.4 fb$^{-1}$ data above $\Lambda_c^+\bar{\Lambda}_c^-$ threshold. From these samples, BESIII has produced many world-leading results in the (exotic) hadron spectroscopy, charmed meson and baryon decays, light baryon and meson decay properties, as well as baryon pair near-threshold productions. To extract intermediate states in multi-particle final states from hadron decays, BESIII develops advanced amplitude analysis tools to carry out multi-dimensional likelihood fits to data with a large set of fitting parameters. Furthermore, to improve detection efficiency and identify rare decay process, several machine learning techniques are deployed in offline reconstruction, detector simulations and physics analysis. In this talk, we will report the progress of implementation of these statistical tools at BESIII.
Current noisy quantum computers can be already used to investigate properties
of quantum systems. Here we focus on lattice QED in (2+1)D including fermionic matter.
This complex quantum field theory with dynamical gauge and matter fields has similarities
with QCD, in particular asymptotic freedom and confinement.
We define a suitable setup to measure the static potential between two static charges as a function of their distance and
use a quantum computation to explore the Coulomb, the confinement and the string breaking regimes.
A symmetry-preserving variational quantum circuit is employed for the creation of the ground state
of the theory at various coupling constant values corresponding to different
physical distances. We confirm that classical simulations for the static potential agree with
quantum simulations of the system and also with results from quantum experiments on a trapped-ion device.
Moreover, we visualize the relevant flux configurations that contribute to the quantum ground state
in the different distance regimes of the potential giving thus insight into the mechanisms
of confinement and string breaking.
GAMBIT - the Global and Modular beyond-Standard Model Inference Tool - is an open-source package for performing global fits of beyond-Standard Model physics theories. I will present the design of the package and some highlights of recent results.
The Compton amplitude is of significant phenomenological interest, particularly at higher momenta, where numerical approaches such as Lattice QCD are required to calculate the Compton amplitude. There are, however, significant challenges to using Lattice QCD at non-zero momentum, not least of which is the reduction in signal to noise ratio. Traditionally, signal to noise ratios are improved by exploiting freedom in interpolator construction, however, at non-zero momenta these methods become less effective. Hence, other methods to reduce noise are needed such as the recently developed Momentum Smearing which modifies traditional quark smearing by including an extra momentum dependent phase factor to the smearing kernel. Here, we use this method to calculate the Compton amplitude for nucleons at high momenta, and further extend the method using variational techniques.
We revisit the Standard Model fit to electroweak precision observables using the latest data and the Particle Data Group value of the mass of the W boson. This analysis is repeated for the value reported by CDF. The constraints on the parameter space for dark photons arising from these electroweak precision observables are then evaluated for both values of the W boson mass. We also extend previous work by placing the first electroweak precision observable constraints on the coupling of dark photons to the fermionic dark matter sector.
Since the matter in neutron stars is stable long term, then to the extent that the cores of such stars are hadronic, one must satisfy the conditions of beta equilibrium and hyperons must be present. The initial appearance of hyperons carries low momentum and thus slows the increase in pressure in comparison to the nucleon only equation of state. In turn, the maximum mass is lowered when hyperons are present. Neutron stars are thought to have a central density between 4-10 times saturation density. At high densities there is good justification for the addition of extra repulsion stemming from the Pauli-exclusion principle, reconfiguration to a multi-quark environment, or even physics beyond the standard model. Here we examine the effects of phenomenological high-density repulsion within the framework of QMC and describe the composition, mass, radii, and tidal deformability from the resulting equation of state.
We perform a comprehensive analysis of the scattering of matter and gravitational Kaluza-Klein (KK) modes in five-dimensional gravity theories. We consider matter localised on a brane and in the bulk of the extra dimension for scalars, fermions and vectors, respectively and consider an arbitrary warped background. While naive power-counting suggests that there are amplitudes that grow as fast as $\mathcal{O}(s^3)$ [where $s$ is the centre-of-mass scattering energy-squared], we demonstrate that cancellations between the various contributions result in a total amplitude which grows no faster than $\mathcal{O}(s)$. Extending previous work on the self-interactions of the gravitational KK modes, we show that these cancellations occur due to sum-rule relations between the couplings and the masses of the modes that can be proven from the properties of the mode equations describing the gravity and matter wavefunctions. We demonstrate that these properties are tied to the underlying diffeomorphism invariance of the five-dimensional theory. We discuss how our results generalise when the size of the extra dimension is stabilised via the Goldberger-Wise mechanism. Our conclusions are particularly relevant for freeze-out and freeze-in relic abundance calculations for dark matter models, including a spin-2 portal arising from an underlying five-dimensional theory.
The CMS group has recently reported an anomaly in the production of particles at ~95 GeV above expected background at the LHC in the ditau and diphoton channels. Taken with an older result from LEP showing a similar anomaly in bb production, this indicates the prospect of a new particle at this energy.
As a possible explanation for these anomalies, we consider a pair of Simplified Models that add an additional Higgs doublet to the Standard Model – realizing the well-known Two-Higgs Doublet Model (2HDM) – as well as an additional scalar or pseudoscalar gauge singlet. We investigate the possibility that the lightest scalar or pseudoscalar state in these models could have a mass of 95 GeV, generating the observed excesses. We also apply relevant bounds from flavour physics (primarily from decays of rare B-mesons), collider physics (resonance and missing transverse energy searches), and Higgs physics to determine if these constraints can be satisfied while still generating the observed excesses.
We find that both models could generate the anomalies seen at the LHC, but neither can effectively reproduce the bb anomaly at the LEP.
We study the impact of Gribov copies on the quark propagator in lattice 2-colour QCD. We find that the Gribov noise is comparable to the gauge noise for smaller volumes but becomes less significant for larger spatial volumes. The Gribov noise in the quark propagator is found to be comparable to, but smaller than in the gluon propagator on the same ensembles. No correlation is found between the values of either of the quark propagator form factors and the value of the gauge fixing functional, nor between the two form factors.
The computation of the four-gluon and ghost-gluon vertices in the Landau gauge using high statistical lattice ensembles for 324 and 484 volumes is addressed. For the four-gluon vertex, our previous results for the collinear kinematics are updated allowing to get a better coverage of the IR region. Furthermore, the one-particle irreducible ghost-gluon Green function in the soft gluon limit is computed covering, with precision, a large momentum region.
In this project we examine a compact U (1) lattice gauge theory in (2 + 1) dimensions and present a strategy
for studying the running coupling and extracting the non-perturbative Lambda-parameter.
The methodology involves a series of sequential steps (i.e., the step scaling function) to bridge results
from small lattice spacings to non-perturbative large-scale lattice calculations.
We propose variational Ansatz circuits adapted to gauge degrees of freedom and demonstrate
that these quantum circuits are able to capture the relevant physics with a future plan to extend them to
fermionic matter fields. In the latter case, one can study phenomena like confinement and asymptotic freedom.
In fact, QED in these dimensions has similarities with Quantum Chromodynamics (QCD) and
it can thus be used as a test bed for future QCD studies.
In this work, we study the expectation value of the plaquette operator, for matching with corresponding Monte Carlo simulations
and also present results for the static potential and static force, which can be related to the renormalized coupling.
One advantage we see in a quantum approach is that it does not suffer from autocorrelation problems
for small values of the bare coupling towards the continuum limit, as in the case with the classical Monte Carlo method.
Whether interested in hadron spectroscopy, nuclear structure, or precision tests of the standard model, three-hadron dynamics play a key role in a broad class of rich physical phenomena. Presently, lattice QCD is the only non-perturbative tool for studying QCD exactly. In this talk, I review novel formal techniques that have allowed to non-perturbatively constraining scattering amplitudes involving three-particle states directly via lattice QCD. As I will discuss, these techniques may also impact future experimental analysis in a variety of processes. Finally, I will present some key lattice QCD calculations, including the first QCD determination of a three-hadron scattering amplitude.
Relativistic heavy-ion collisions at the LHC create the quark–gluon plasma (QGP); a state of matter where quarks and gluons are not confined inside hadrons. In this review talk I will show what measurements of key observables in Pb-Pb, Xe-Xe, p-Pb and pp collisions at the LHC experiments have taught us about the hottest fluid ever studied in the laboratory and what this tells us about the enigmatic QGP properties. I will focus on the road ahead and present what the current key open questions are and how we plan to address these in the coming decade using precise measurements of rare probes such as heavy-quarks and di-leptons.
Sasha Andrianov passed away a few months ago. His work span more than four decades in high energy physics, with very significan contributions associated to current trends in the theory of elementary particles: bosonization of quantum chromodynamics, Higgs physics, cosmology of complex systems, supersymmetric quantum mechanics, anomalies in quantum field theory, local parity violation under extreme conditions, and many more. In this talk I shall try to review the most important milestones of his work by placing them in their time and context. A great person and a great physicist. We miss him.
We calculate the leading and subleading corrections to the real-time static potential in a high-temperature quark-gluon plasma for distances smaller than the screening length. The calculation involves one-loop two and four point functions in the hard-thermal-loop effective theory. We apply our results to estimate the dissociation temperature, the thermal mass shift and the thermal decay width of the bottomonium ground state. We compare them with lattice results in the literature.
The propagation of colored quarks and subsequent formation of hadrons in the nuclear medium are the phenomena closely related to the fundamental processes in QCD. This topic has captivated the interest of diverse scientific communities, ranging from Deep Inelastic Scattering (DIS) to Drell-Yan and Heavy-Ion collisions. A unique feature of semi-inclusive DIS is its ability to investigate time-dependence of color propagation and hadronization processes by embedding it in well understood nuclear medium of increasing size allowing for studies of a variety of important partonic and hadronic processes. These include characteristics of light and heavy hadron formation and attenuation, quark energy loss, diquark searches, di-hadron and Bose-Einstein correlations which will be discussed in this talk in the framework of experimental data gathered from Jefferson Lab and complimented by QCD-based phenomenological analyses.
Heavy-ion collisions are a gateway to understanding quantum chromodynamics under extreme conditions. At such high energies, heavy quarks become important, and via the use of effective field theories, their behaviour can be related to a correlator of chromoelectric fields. Studying it in the high-temperature background relevant for heavy-ion collisions lets one, for example, extract the transport properties of matter. In particular, chromoelectric field correlators in the adjoint representation relate to the physics of quarkonium, bound states of heavy quark-antiquark pairs.
I will present a perturbative evaluation of the adjoint chromoelectric correlator at finite temperatures in Euclidean space. With modern thermal IBP methods for handling the relevant loop integrals, the computation can be easily automated and the integrals reduced to a far simpler form than those encountered in the past. Applying this explicitly to correlators at NLO, I will also discuss potential extensions to higher orders in perturbation theory, as well as the steps necessary for obtaining the transport coefficients with this method. The Euclidean computation is particularly useful for comparisons with lattice simulations, and a detailed breakdown of the loop integrals and their structure provides an analytic understanding of some features of the lattice results.
Using the potential non-relativistic quantum chromodynamics (pNRQCD) effective field theory in an open quantum system, we derive a Lindblad equation for the evolution of the heavy-quarkonium reduced density matrix that is accurate to next-to-leading order (NLO) in the ratio of the binding energy of the state to the temperature of the medium [1]. The resulting NLO Lindblad equation can be used to more reliably describe heavy-quarkonium evolution in the quark-gluon plasma at low temperatures compared to the leading-order truncation. For phenomenological application, we numerically solve the resulting NLO Lindblad equation using the quantum trajectories algorithm. Averaging over the Monte-Carlo sampled quantum jumps, we obtain the solution to the NLO Lindblad equation without truncation in the angular momentum quantum number of the states considered. We demonstrate the importance of quantum jumps in the nonequilibrium evolution of bottomonium states in the quark-gluon plasma [2]. We show that quantum regeneration of singlet states from octet configurations is necessary to understand experimental results for the suppression of both bottomonium ground and excited states. The values of the heavy-quarkonium transport coefficients used are consistent with recent lattice QCD determinations.
References:
[1] N. Brambilla, M.A. Escobedo, A. Islam, M. Strickland, A. Tiwari, A. Vairo, and P. V. Griend. ``Heavy quarkonium dynamics at next-to-leading order in the binding energy over temperature.'' JHEP, 08:303, 2022.
[2] N. Brambilla, M.A. Escobedo, A. Islam, M. Strickland, A. Tiwari, A. Vairo, and P. V. Griend. ``Regeneration of bottomonia in an open quantum systems approach.'', Phys.Rev.D 108 (2023) 1, L011502.
The FASTSUM collaboration has a long-standing project examining hadronic properties using anisotropic lattice QCD. I will introduce our efforts to determine the spectral properties of bottomonia at finite temperature using lattice NRQCD and describe how our newer simulations improve our control over systematic errors. Motivated by these efforts, I will discuss the temperature dependence of charm hadron masses where it is found that temperature effects can extend into the confining phase and that some species remain stable deep past the deconfinement temperature.
In recent experiments in the heavy quark sector, various candidates of exotic hadrons have been observed. Most of exotic hadrons are discovered near the threshold of two-body scattering as represented by $T_{cc}$ and $X(3872)$ [1,2]. Such near-threshold states are empirically considered as hadronic molecules [3]. To focus on the molecular structure, it is useful to calculate the compositeness, the fraction of the hadronic molecule component in the wavefunction [4]. By using the compositeness, we demonstrate that near-threshold bound states are usually molecular dominant [5] which is consistent with the consequence of the low-energy universality [6]. When we consider the decay and coupled-channels effects which are important for the exotic hadrons, the compositeness is found to be suppressed by these effects [5]. As an application, we discuss the internal structure of $T_{cc}$ and $X(3872)$ by using a new interpretation of the complex compositeness [7].
[1] LHCb Collaboration, Nat. Commun. 13, 3351 (2022); Nat. Phys. 18, 751 (2022).
[2] S.-K. Choi et al. (Belle Collaboration), Phys. Rev. Lett. 91, 262001 (2003).
[3] F. K. Guo et al., Rev. Mod. Phys. 90, 015004, (2018)
[4] T. Kinugawa and T. Hyodo, Phys. Rev. C 106, 015205 (2022).
[5] T. Kinugawa and T. Hyodo, Phys. Rev. C 109, 045205 (2024).
[6] T. Hyodo, Phys. Rev. C 90, 055208 (2014).
[7] T. Kinugawa and T. Hyodo, arXiv:2403.12635 [hep-ph].
The doubly charmed tetraquark $T^+_{cc}$ recently discovered by the LHCb Coll. is studied by using (2+1)-flavor lattice QCD simulations with nearly physical pion mass $m_\pi=146$ MeV. The interaction between $D^*$ and $D$ in the isoscalar and $S$-wave channel extracted from the hadronic spacetime correlation by the HAL QCD method is attractive and leads to a near-threshold virtual state with a pole position $E_\text{pole}\simeq-59$ keV. The virtual state is shown to evolve into a loosely bound state as $m_\pi$ decreases to its physical value by using a potential modified to $m_\pi=135$ MeV based on the pion-exchange interaction. Such a potential is also able to describe the LHCb data on the $D^0D^0\pi^+$ mass spectrum.
We have studied the mass spectra of doubly charm pentaquark states in the $\Lambda_{c}^{(*)}D^{(*)}$ and $\Sigma _{c}^{(*)}D^{(*)}$ channels with various quantum numbers in QCD sum rules. We use the parity projected sum rules to separate the contributions of negative and positive parities from the two-point correlations induced by the pentaquark interpolating currents. Our results show that the bound states of $P_{cc}$ pentaquarks may exist in the $\Lambda _cD\, (\frac{1}{2}^-)$, $\Sigma _cD\, (\frac{1}{2}^-)$, $\Sigma _cD^*\, (\frac{3}{2}^-)$, $\Lambda _c^*D\, (\frac{3}{2}^-)$, $\Lambda _c^*D^*\, (\frac{5}{2}^-)$ channels with negative-parity and $\Sigma _cD\, (\frac{1}{2}^+)$, $\Sigma _cD^\ast\, (\frac{3}{2}^+)$, $\Sigma _c^\ast D\, (\frac{3}{2}^+)$ channels with positive-parity, since their masses are predicted to be lower than the corresponding meson-baryon thresholds. However, they are still allowed to decay into the $\Xi_{cc}^{(\ast)}\pi$ final states via strong interaction. The triply charged $P_{cc}^{+++}(ccuu\bar d)$ and neutral $P_{cc}^{0}(ccdd\bar u)$ in the isospin quartet would definitely be pentaquark states due to their exotic charges. We suggest searching for these characteristic doubly charmed pentaquark signals in the $P_{cc}^{+++}\to\Xi_{cc}^{(\ast) ++}\pi^+/\rho^+$, $\Sigma_c^{(\ast)++}D^{(\ast)+}$ and $P_{cc}^{0}\to\Xi_{cc}^{(\ast) +}\pi^-/\rho^-$, $\Sigma_c^{(\ast)0}D^{(\ast)0}$ decays in the near future.
The T_cc^+ is a a doubly charmed tetraquark that lies very close to the D^* D meson thresholds. As such it can be described as a molecular bound state in an effective field theory (EFT) of heavy mesons. An EFT calculation of the width is in excellent agreement with experiment and also successfully reproduces the invariant mass spectrum of the D mesons in the three body decays of the T_cc^+. This latter observable is particularly sensitive to the molecular nature of the T_cc^+. An NLO calculation in EFT continues to be in excellent agreement with experiment and leading sources of uncertainty are sensitive to scattering properties of D mesons.
We have investigated the internal structure of the open- and hidden-charmed($DD^∗/D\bar{D}^∗$) molecules in the unified framework. We first fit the experimental lineshape of the $T^+_{cc}$ state and extract the $DD^∗$ interaction, from which the $T^+_{cc}$ is assumed to arise solely. Then we obtain the $D\bar{D}^∗$ interaction by charge conjugation. Our results show that the $D\bar{D}^∗$ interaction is attractive but insufficient to form $X(3872)$. Instead, its formation requires the crucial involvement of the coupled channel effect between the $D\bar{D}^∗$ and ccbar components, although the ccbar accounts for approximately $1\%$ only. Besides $X(3872)$, we have obtained a higher-energy state around $3957.9$ MeV with a width of $16.7$ MeV, which may be a potential candidate for the $X(3940)$. In $J^{PC} = 1^{+−}$ sector, we have found two resonances related to the iso-vector $Z_c$ and the iso-scalar $h_c(2P)$, respectively. Our combined study provides valuable insights into the nature of these $DD^∗/D\bar{D}^∗$ exotic states.
Chiral trajectories of dynamically generated resonances are connected to the SU(3) breaking pattern and their nature. From an analysis of a recent LQCD simulation on the $\pi\Sigma-\bar{K}N$ scattering for $I=0$, and the study of the quark mass dependence of the octet baryons, we determine for the first time the trajectory of the two poles associated to the $\Lambda(1405)$ towards the symmetric point ($\mathrm{Tr}[M]=\mathrm{cte})$ accurately. Our result at unphysical pion mass is consistent with the lattice simulation at $m_\pi\simeq 200$ MeV and the extrapolation to the physical point, based on the NLO chiral lagrangian, agrees perfectly well with previous analyses of experimental data. Contrary to other works, we predict qualitatively similar trajectories at LO and up to NLO, being consistent with the dominance of the LO interaction. At the SU(3) symmetric point up to NLO, we obtain that the lower pole is located at $E^{(1)}=1595\pm8$ MeV, being a singlet representation, while the higher pole belongs to the octet with a mass $E^{(8)}=1600\pm4$ MeV. This can be tested in the future LQCD simulations.
At BESIII, the electromagnetic form factors (EMFFs) and the pair production cross sections of various baryons have been studied. The proton EMFF ratio |GE/GM| is determined precisely and line-shape of |GE| is obtained for the first time. The recent results of neutron EMFFs at BESIII show great improvement comparing with previous experiments. Cross sections of various baryon pairs (Lambda, Sigma, Xi, Lambdac) are studied from their thresholds. Anomalous enhancement behavior on the Lambda and Lambdac pair are observed. The relative phase of EMFFs for Lambda and Sigma+ are measured for the first time.
The rare radiative $K^+\to\pi^+\ell^+\ell^-$ decays ($\ell=e,\mu$) provide experimental access to the $K^+\to\pi^+\gamma^*$ transition. The relevant form factor is conventionally written in terms of two hadronic parameters, $a_+$ and $b_+$, which are being measured by NA62 in both electron and muon channels. Comparing the two channels allows for a stringent test of lepton-flavor universality. However, appropriate experimental analysis requires adequate theory inputs: Although the $K^+\to\pi^+\gamma^*$ conversion has been studied extensively, radiative corrections involve the $K^+\to\pi^+\gamma^*\gamma^{(*)}$ transitions (with up to two virtual photons), not fully addressed in the literature. At the same time, the $K^+\to\pi^+\gamma^*\gamma^*$ transition is essential for the description of the $K^+\to\pi^+e^+e^-\ell^+\ell^-$ decays, which represent a background to new-physics searches.
We study the $J/\psi \to \phi \pi^+ a_0(980)^- (a_0^- \to \pi^- \eta)$ decay, evaluating the double mass distribution in terms of the $\pi^- \eta$ and $\pi^+ a^-_0$ invariant masses. We show that the $\pi^- \eta$ mass distribution exhibits the typical cusp structure of the $a_0(980)$ seen in recent high statistics experiments, and the $\pi^+ a^-_0$ spectrum shows clearly a peak around $M_{\rm inv}(\pi^+ a^-_0)=1420 \,{\rm MeV}$, corresponding to a triangle singularity. When integrating over the two invariant masses we find a branching ratio for this decay of the order of $10^{-5}$, which is easily accessible in present laboratories. We also call the attention to the fact that the signal obtained is compatible with a bump experimentally observed in the $\eta \pi^+\pi^-$ mass distribution in the $J/\psi \to \phi \eta \pi^+\pi^-$ decay and encourage further analysis to extract from there the $\phi \pi^+ a_0^-$ and $\phi \pi^- a_0^+$ decay modes.
Recently, two experiments in Hall C at Jefferson Lab finished data taking. One experiment focused on a precision measurement of the virtual photon asymmetry A$_1^n$ at large values of Bjorken-x (0.61 < x < 0.77) at various values of Q$^2$, and the other experiment measured the spin structure function g$_2^n$ over a large range of Bjorken-x (0.20 < x < 0.95) to extract the Q$^2$ evolutions of the twist-3 matrix element, d$_2^n$(Q$^2$), at three different values of Q$^2$ (3.0 GeV$^2$ < Q$^2$ < 5.60 GeV$^2$). Details of the experiments and an update of the data analyses will be presented.
This research is partially supported by the Office of Nuclear Physics of the DOE Office of Science, Grant Number: DE-FG02-99ER41101
The high-precision study of multi-nucleon matrix elements via lattice QCD requires numerical resources that increase dramatically with the number of nucleons, due to signal-to-noise degradation and a factorial number of Wick contraction terms. To address this, we present a particular variant of e-graphs (equality graphs) called tensor e-graphs which construct composite tensors that are ‘maximally’ re-used within the numerical evaluation of a set of tensor expressions. By applying tensor e-graph optimisation to multi-nucleon matrix elements, we present speed-ups for a range of interpolating operators. We also show how an extension of Feynman-Hellmann theorem techniques developed for forward Compton virtual photon-nucleon scattering in concert with e-graph optimisation can enable a pathway to high-precision study of virtual photon-multi-nucleon scattering using lattice QCD.
We investigate the roles of the electromagnetic interaction in the photoproductions and radiative decays of nucleon excitations and exotic heavy hadrons, as well as their relevant electromagnetic form factors. Our quantitative investigation shows that their electromagnetic properties can provide important hints to decode the inner structure of hadrons. The electromagnetic processes can better reflect the difference between the charged and neutral components, since the electromagnetic interaction explicitly breaks the isospin symmetry. The study of electromagnetic properties will help us disclose further the structure of these unconventional states.
The color/quark deconfinement is one of the remarkable features of QCD phase transitions, with the observation of (strongly coupled) quark-gluon plasma in the heavy-ion collision experiments. In phenomenology, the deconfinement phase transition corresponds to the Polyakov loop which symbols the glue dynamics.
In this talk, I will discuss the relevance of the Polyakov loop for the QCD thermodynamic functions.
Firstly, I'll show the impact of the Polyakov loop on the quark sector and on the evolution trajectories of the QCD system, in a combined study with the hydrodynamic simulation, and also in a cosmological study.
Moreover, I will discuss the nonperturbative determination of the Polyakov loop potential via the Dyson-Schwinger equations (DSEs), and introduce some new progress about the DSEs study on the baryon number fluctuations and the finite-density QCD equation of state.
I will report the three-dimensional structure of the proton obtained from a recently constructed nonperturbative approach based on the light-front Hamiltonian formalism, named Basis Light-front Quantization (BLFQ). First, we obtain the light-front wave function of the proton through solving the eigenvalue problem of the light-front Hamiltonian of QCD in $|qqq\rangle$+$|qqqg\rangle$+$|qqqq\bar q\rangle$ Fock sectors. Next we calculate the generalized parton distribution functions (GPDs) of the proton in momentum space based on the overlap of the obtained light-front wave functions. Finally, by Fourier transforming the proton GPDs into the impact parameter space we obtain the spatial imaging of the proton in terms of its constituent quarks, gluons and anti-quarks. In this talk, I will present our numerical results on the three-dimensional distribution of the valence quarks, the gluon as well as the sea quarks inside the proton.
A precision determination of the pion-nucleon sigma term requires the consideration of isospin-breaking corrections, given that such effects are enhanced due to the chiral suppression of the isoscalar pion-nucleon amplitude. In particular, when comparing phenomenological and lattice-QCD determinations, it is critical that consistent definitions be employed. In the talk, I will give an update on the determination of the sigma term from pion-nucleon scattering, focusing on the role of isospin violation.
Modern few- and many-body simulations of nuclei rely on precise nuclear forces and electro-weak currents. A powerful tool which makes such high-precision calculations possible without losing connection to Quantum Chromodynamics (QCD), the fundamental theory of the strong interaction, is chiral effective field theory (EFT). Instead of working directly with quarks and gluons it is more efficient to formulate an effective field theory of QCD with pions and nucleons as explicit degrees of freedom. The relevant symmetries of QCD are by construction implemented in chiral EFT and equip one with a small expansion parameter in the low energy sector. Nuclear forces and currents can then be determined via perturbation theory. The increase of precision is achieved by going to higher orders in this expansion.
In my talk I will review the current status of the construction and implementation of chiral nuclear forces: I will show that in order to get chiral three-nucleon forces at next-to-next-to-next-to-leading order (N3LO) one has to use symmetry-preserving cut-off regulator, otherwise one violates chiral symmetry at N3LO. I will present powerful techniques like symmetry-preserving gradient-flow regularization and novel path-integral approach for construction of nuclear forces and will present the current status of their application.
The SABRE experiment aims to detect an annual rate modulation from dark matter interactions in ultra-high purity NaI(Tl) crystals in order to provide a model independent test of the signal observed by DAMA/LIBRA. It is made up of two separate detectors that rely on joint crystal R&D activity; SABRE South located at the Stawell Underground Physics Laboratory (SUPL), in regional Victoria, Australia, and SABRE North at the Laboratori Nazionali del Gran Sasso (LNGS).
SABRE South is designed to disentangle seasonal or site-related effects from the dark matter-like modulated signal by using an active veto and muon detection system. Ultra-high purity NaI(Tl) crystals are immersed in a Linear Alkyl Benzene (LAB) based liquid scintillator veto, further surrounded by passive steel and polyethylene shielding and a plastic scintillator muon veto. Significant work has been undertaken to understand and mitigate the background processes, taking into account radiation from the detector materials, from both intrinsic and cosmogenic activated processes, and to understand the performance of both the crystal and veto systems.
SUPL is a newly built facility located 1024 m underground (~2900 m water equivalent) within the Stawell Gold Mine and its construction has been completed in 2023.
The commissioning of SABRE South started in early 2024 and the first equipment including the muon detectors have been already installed in SUPL.
This talk will report on the general status of the SABRE South assembly, its expected performance, and the design of SUPL.
Two-color ($N_c=2$) QCD world is one of the useful testing grounds to delineate cold and dense QCD matter, since the lattice QCD simulation is straightforwardly applicable thanks to the disappearance of the sign problem. Motivated by recent numerical results from the lattice QCD activities, I am being investigating properties of dense two-color QCD by constructing the linear sigma model (LSM). In this talk, I summarize my recent works based on my LSM, such as the modifications of hadron mass spectrum, topological susceptibility, and the sound-velocity peak in cold and dense two-color QCD.
References:
[1] D. Suenaga, K Murakami, E. Itou and K. Iida, Phys.Rev.D 107 (2023) 5, 054001,
[2] M. Kawaguchi and D. Suenaga, JHEP 08 (2023) 189,
[3] D. Suenaga, K. Murakami, E. Itou, K. Iida, 2312.17017 [hep-ph] (to appear in Phys.Rev.D),
[4] M. Kawaguchi and D. Suenaga, 2402.00430 [hep-ph].
Since the EMC effect indicates modification of quark distribution in the nucleons inside the nucleus, the properties and structure of nucleons might be modified in the nucleus. However, it is still unclear. In order to correctly describe high-density nuclear matter in neutron stars, this problem should be also studied, as well as the nuclear force in dense nuclear matter.
We are planning to experimentally investigate possible modification of baryons in nuclei by using hyperons in hypernuclei. The J-PARC E63 experiment will investigate possible change of the magnetic moment of the Λ hyperon in hypernuclei by measuring the B(M1) value of the Λ’s spin-flip 7ΛLi(3/2+ -> 1/2+) transition.
Another experiment will study possible change of the Λ’s beta-decay rate in hypernuclei. The Quark Meson Coupling model predicts a reduction of the beta-decay rate up to 20% by baryon modification. We are considering an experiment at J-PARC to measure the beta-decay rate precisely via the beta-decay branching ratio and the lifetime of the Λ in hypernuclei such as 5ΛHe and 13ΛC. We are currently designing the detectors, but precise estimates of various nuclear effects in the Λ’s beta decay are essential, and we strongly need the advice and cooperation by theorists.
Neutron scattering off neutron halos can provide important information about the internal structure of nuclei close to the neutron drip line. In this work, we use halo effective field theory to study the $s$-wave scattering of a neutron and the spin-parity $J^P=\frac{1}{2}^+$ one-neutron halo nuclei $^{11}\rm Be$, $^{15}\rm C$, and $^{19}\rm C$ at leading order. In the $J=1$ channel, the only inputs to the Faddeev equations are their one-neutron separation energies. In the $J=0$ channel, the neutron-neutron scattering length and the two-neutron separation energies of $\rm ^{12}Be$, $\rm ^{16}C$ and $\rm ^{20}C$ enter as well. The numerical results show that the total $s$-wave cross sections in the $J=1$ channel at threshold are of the order of a few barns. In the $J=0$ channel, these cross sections are of the order of a few barns for $n$-$^{11}\rm Be$ and $n$-$^{19}\rm C$ scattering, and about 60 $\rm mb$ for the $n$-$^{15}\rm C$ scattering. The appearance of a pole in $p\cot\delta$ close to zero in all three cases indicates the existence of a virtual Efimov state close to threshold in each of the $^{12}\rm Be$, $^{16}\rm C$, and $^{20}\rm C$ systems. Observation of this pole would confirm the presence of Efimov physics in halo nuclei. The dependence of the results on the neutron-core scattering length is also studied.
We present a method for computing energy spectra in quantum field theory by digital quantum simulation. We utilize a quantum algorithm called coherent imaging spectroscopy which quenches the ground state with an oscillating perturbation in time and then reads off the excited energies from the vacuum persistence probability following the quench. We demonstrate this method in the lattice Schwinger model using a classical simulator and compare the results with expectations from the continuum limit. The estimation of computational complexity implies that the method is potentially efficient in early fault-tolerant quantum computer era.
We introduce Nuclear Co-Learned Representations (NuCLR), a deep learning model that predicts various nuclear observables, including binding and decay energies, and nuclear charge radii. The model is trained using a multi-task approach with shared representations and obtains state-of-the-art performance, achieving levels of precision that are crucial for understanding fundamental phenomena in nuclear (astro)physics. We also report an intriguing finding that the learned representation of NuCLR exhibits the prominent emergence of crucial aspects of the nuclear shell model, namely the shell structure, including the well-known magic numbers, and the Pauli Exclusion Principle. This suggests that the model is capable of capturing the underlying physical principles and that our approach has the potential to offer valuable insights into nuclear theory.
In high energy physics, it is challenging to estimate precisely the trials factor for a resonance search with an unspecified mass. A relatively new approach is to model the significance derived from the likelihood ratio (fit a spectrum with and without the presence of the resonance in the statistical model) as a Gaussian Process. The knowledge of the covariance of the significance between different mass points in the search region is the key. Two published approaches for estimating the covariance are presented. The first is based on fits to a carefully designed set of Asimov-like background samples, where individual fluctuations of the background sample are introduced in each sample. The second approach is based on a linear expansion of the likelihood ratio and requires surprisingly little computation. The second approach actually justifies the somewhat ad-hoc first approach. The approaches have been tested extensively with high-statistics samples of toy Monte Carlo experiments and several different statistical models (including a 2-D model with unspecified mass and width). Depending on how fast the ATLAS collaboration works, it may be possible to show results from the application of the second approach to an actual resonance search at the LHC.
The unfolding problem is to make inferences about the true particle spectrum based on smeared observations from a detector. This is an ill-posed inverse problem, where small changes in the smeared distribution can lead to large fluctuations in the unfolded distribution. The forward operator is the response matrix which models the detector response. In practice, the forward operator is rarely known analytically and is instead estimated using Monte Carlo simulation. This raises the question of how to best estimate the response matrix and what impact this estimation has on the unfolded solutions. In most analyses at the LHC, response matrix estimation is done by binning the true and smeared events and counting the propagation of events between the bins. Unexpectedly, we find that the noise in the estimated response matrix can inadvertently regularize the problem. As an alternative, we propose to use conditional density estimation to estimate the response kernel in the unbinned space followed by binning this estimator. Using a simulation study, we investigate the performance of the two approaches. Finally, we discuss how a new class of unfolding techniques might eliminate the need for plug-in response matrix estimation, hence simplifying this aspect of the unfolding problem.
In recent years, machine learning and AI technologies have revolutionized physics, becoming essential in overcoming the enormous computational costs and time constraints faced by traditional methods. This talk will discuss their applications in lattice QCD and related fields. We will introduce new configuration generation methods for lattice QCD using gauge-covariant neural networks and self-learning Monte Carlo methods, as well as the application of transformers respecting global symmetries. These methods excel at capturing long-range correlations, as evidenced by the success of models like ChatGPT and AlphaFold. Additionally, we will cover the use of sparse modeling for spectral function analysis and decision tree algorithms for higher-order 1/D estimation, exploring their potential for susceptibility calculations and Taylor expansions.
We investigate the internal structure of deuteron using the light-front wave functions obtained from the two Schrödinger-like equations: the light-front holographic QCD equation and the 't Hooft equation. The former governs the transverse dynamics inside the composite system, while the latter describes the confinement in the longitudinal direction. After generating the wave functions, we employ them to investigate the electromagnetic form factors, structure functions and tensor-polarized properties of the deuteron. As a spin-one system, deuteron exhibits a unique structure, more complex than that of spin-0 and spin-1/2 systems. We also briefly discuss the investigation of this system using the basis light-front approach, wherein we solve for the wave functions by considering the fundamental QCD interactions among the quarks and gluons inside the deuteron.
Composite Higgs Models offer an attractive solution to the hierarchy problem. We extend previously examined models based on a SO(5) → SO(4) symmetry breaking pattern and 3rd generation quarks, with two representations of the τ and its neutrino. We conduct Bayesian global fits of these models using a wide array of constraints in order to find regions in the parameter volume that best fit experimental measurement. We then study the effects of including lepton parameters and constraints on the fit results for similar scans, as well as analyse the fine-tuning of each model by calculating the Kullback-Lieber divergence between their respective priors and posteriors, and the robustness of each scan. Both models were found to satisfy all constraints at the 3σ level and capable of predicting gluon-fusion produced Higgs signal strengths that are agreeable with the Standard Model order of unity. Additionally, we present the predicted leptons' experimental signatures for valid points in said models and discuss their potential phenomenology at future high-luminosity LHC runs.
Observations of neutron stars place the upper mass limit at above 2 solar masses. Since the matter in neutron stars is stable long term, then to the extent that the cores of such stars are hadronic, one must satisfy the conditions of beta equilibrium and hyperons must be present. The initial appearance of hyperons carries low momentum and thus slows the increase in pressure in comparison to the nucleon only equation of state. In turn, the maximum mass is lowered when hyperons are present. Neutron stars are thought to have a central density between 4-10 times saturation density. At high densities there is good justification for the addition of extra repulsion stemming from the Pauli-exclusion principle, reconfiguration to a multi-quark environment, or even physics beyond the standard model. Here we examine the effects of phenomenological high-density repulsion within the framework of QMC and describe the composition, mass, radii, and tidal deformability from the resulting equation of state.
Gauge p-forms in diverse dimensions naturally occur in supergravity and string theory. This talk will review new formulations for interacting gauge p-form theories in d = 2p + 2 space-time dimensions. For odd p, such theories possess U(1) duality invariance and include the Born-Infeld action as a well-known representative. For even p, each theory describes a self-interacting chiral boson with a self-dual field strength. In the four-dimensional case, an important example is a low-energy effective action for the N = 4 supersymmetric Yang-Mills theory on its Coulomb branch where the gauge group SU(n) is spontaneously broken to SU(n-1) x U(1) and the dynamics is described by a single N = 2 this effective action will be briefly discussed.
We proposed that the parity-violating electron scattering (PVES) offers a powerful tool to probe the hypothetical dark photon. We calculated the dark photon contributions to PVES asymmetries in both elastic and deep-inelastic scatterings (DIS). These contributions are characterized by the corrections to the standard model couplings $C_{1q}, \, C_{2q}$, and $C_{3q}$.
At low scales, the corrections to $C_{1q}$ and $C_{3q}$ could be as large as $5\%$ were a dark photon to exist. In DIS at very high $Q^2$, of relevance to HERA or the EIC, the dark photon could induce substantial corrections to $C_{2q}$, suggesting as large as $10\%$ uncertainties in the extraction of valence parton distribution functions.
We also extract the favoured region of the dark photon parameter space by fitting the experimental data of PVES and atomic parity-violation, which prefers a heavy dark photon with mass above the Z-boson mass.
In the presence of a deconfined medium, scattering amplitudes slightly change, leaving an imprint on jet production. Precise measurements of these modified jets thus infer knowledge of the QGP phase compared to standard perturbative QCD calculations. In this talk, we review the theory of jets and their modification in a deconfined plasma on the ground of perturbation theory. We introduce a general formalism that comprehensively discusses jet-quenching models and allows us their comparison. We review the most recent progressions of jet-medium interaction and their possible applications in jet description.
The LHC Runs 5 and 6 will provide high luminosity pp and Pb-Pb collisions and options for pA and lighter AA systems are under study. ATLAS and CMS will upgrade their detectors during LS3, LHCb is planning a major upgrade for LS4. The ALICE Collaboration is proposing a completely new apparatus, ALICE 3, for the LHC Runs 5 and 6. The ALICE 3 detector consists of a large pixel-based tracking system covering eight units of pseudorapidity, complemented by multiple systems for particle identification, including silicon time-of-flight layers, a ring-imaging Cherenkov detector, a muon identification system, and an electromagnetic calorimeter. ALICE 3 will enable novel studies of the quark-gluon plasma and open up important physics opportunities in other areas of QCD and beyond. New studies in the QGP sector will focus on low-pT heavy-flavour production, including beauty hadrons, multi-charm baryons and charm-charm correlations, as well as on precise multi-differential measurements of dielectron emission to probe the mechanism of chiral-symmetry restoration and the time-evolution of the QGP temperature. Besides QGP studies, ALICE 3 can uniquely contribute to hadronic physics, with femtoscopic studies of the interaction potentials between charm mesons and searches for nuclei with charm. The presentation will cover the detector concept, the physics performance, and the status of novel sensor R&D.
The ALICE experiment has provided numerous insights into the properties and behavior of the quark-gluon plasma (QGP), greatly advancing our understanding of this state of matter in the early universe and the fundamental properties of QCD matter under extreme conditions. This talk will present the latest ALICE results covering topics such as collective dynamics, correlations and fluctuations, heavy flavors, Quarkonia, jets and high pT hadrons, electromagnetic probes, small system physics and the ongoing upgrade program. This talk will highlight some of the selected results.
In this talk, I will present a novel effective-field-theory-based approach for extracting two-body scattering information from finite volume energies. By explicitly incorporating one-pion exchange, we overcome the challenging left-hand cut problem in Lüscher’s method and can handle finite volume energy levels both below and above the left-hand cut. Additionally, we utilize the plane wave basis instead of the conventional partial wave expansion to account for partial wave mixing effects resulting from rotational symmetry breaking in a cubic box. Applied to the lattice data for DD^* scattering at a pion mass of 280 MeV, it reveals the significant impact of the one-pion exchange interaction. This study demonstrates, for the first time, that two-body scattering information can be reliably extracted from lattice spectra including the left-hand cut.
Recent measurements of polarization phenomena in relativistic heavy ion collisions have aroused a great interest in understanding dynamical spin evolution of the QCD matter. In particular, the spin alignment signature of $J/\psi$ has been recently observed in Pb-Pb collisions at LHC, which may infer nontrivial spin transport of quarkonia in quark gluon plasmas. Consequently, we study the spin-dependent in-medium dynamics of quarkonia by using the potential nonrelativistic QCD (pNRQCD) and the open quantum system framework. By considering the Markovian condition and applying the Wigner transformation upon the diagonal spin components of the quarkonium density matrix with the semiclassical expansion, we systematically derive the Boltzmann transport equation for quarkonia with polarization dependence in the quantum optical limit. Unlike the spin-independent collision terms governed by certain chromoelectric field correlators, new gauge invariant correlators of chromomagnetic fields determine the recombination and dissociation terms with polarization dependence at the order we are working. We also derive a Lindblad equation describing the in-medium transitions between spin-singlet and spin-triplet heavy quark-antiquark pairs in the quantum Brownian motion limit. The Lindblad equation is governed by new transport coefficients defined in terms of the chromomagnetic field correlators. Our formalism is generic and valid for both weakly-coupled and strongly-coupled quark gluon plasmas. It can be further applied to study spin alignment of vector quarkonia in heavy ion collisions.
I will review the status of theoretical development and analysis results related to searches for the $\pi_1$ exotic hybrid meson.
The recent PRad experiment at Jefferson Lab has precisely measured the cross sections for elastic electron proton scattering at four momentum transfer square ($Q^2$) from $2\times10^{-4}$ to $6\times10^{-2}$ GeV$^2$/c$^2$. The charge radius of proton was extracted based on the measured proton form factors at very low $Q^2$. This experiment utilized a high precision, hybrid calorimeter (HyCal) that can precisely determine the energy and position of electrons and photons. The HyCal's inner array of PbWO$_4$ modules can also separate two incident particles with a distance greater than about 30 mm ($\sqrt{2}$ of the module size) on the detection plane. Together with the GEM detectors placed in front of the HyCal, which serve as a veto detector for neutral particles, the PRad detector system is capable of measuring and identifying the scattered electrons and the radiative photons simultaneously from the elastic $ep$ scattering process. In this talk, I will present the preliminary results of the direct radiative effects measurement from the PRad experiment. I will also discuss the expected improvements with the upcoming PRad-II experiment.
The dominant contribution to the theoretical uncertainty in the extracted weak parameters of the Standard Model comes from the hadronic uncertainties in the electroweak box diagrams, i.e. $\gamma-W^\pm/Z$ exchange diagrams. A dispersive analysis relates the box diagrams to the parity-odd structure function, $F_3$, for which the experimental data either do not exist or belong to a separate isospin channel. Therefore a first-principles calculation of $F_3$ is highly desirable.
In this contribution, I report on the CSSM/QCDSF/UKQCD Collaboration's progress in calculating the moments of the $F_3^{\gamma Z}$ structure function from the forward Compton amplitude at the SU(3) symmetric point. We focus on the first moment of $F_3^{\gamma Z}$ for a range of $Q^2$ values. We discuss the implications of our results for the electroweak box diagrams along with the possibility of a determination of the strong coupling constant via the Gross-Llewellyn Smith sum rule.
Using a confining version of the Nambu-Jona--Lasinio model we present results for the transverse momentum dependent parton distribution functions (TMDs) of the free nucleon and also a nucleon bound in nuclear matter. We study how nuclear medium effects impact quark transverse momentum. Implications for the EMC effect and semi-inclusive deep inelastic experiments on nuclear targets will also be discussed.