Building on previous studies of the nucleon spectrum and the enigmatic Roper resonance, we investigate the closely related $ \Delta $ baryon spectrum using a combination of lattice QCD and Hamiltonian Effective Field Theory (HEFT). We obtain effective masses for the ground state and first excitation of the spin-3/2 $ \Delta $ baryon in full QCD using 2+1 flavour PACS-CS gauge field...
Systems such as $\mathrm{K^- p}$ and baryon--antibaryon ($\mathrm{B\overline{B}}$) are both characterized by the presence of strong inelastic channels at the production threshold, which can affect the properties and the formation of bound states and resonances.\
In the $\mathrm{\overline{K}N}$ system, the $\Lambda(1405)$ arises from the interplay between the $\mathrm{\overline{K}N}$ and the...
The strong interaction between an antikaon and a nucleon is at the origin of various interesting phenomena in kaon-nuclear systems [1]. In particular, the interaction in the isospin $I=0$ channel is sufficiently attractive to generate a quasi-bound state, the $\Lambda(1405)$ resonance, below the $\bar{K}N$ threshold. Based on this picture, it may be expected that the $\bar{K}N$ interaction...
Wilsonian renormalization group with a multitude of cutoff parameters will be presented. Applications of Gell-Mann-Low and Winsonian Renormalization groups to problems of baryon-baryon scattering and halo nuclei in low-energy EFT will be considered.
Excited states, which show up as resonances embedded in the continuum spectrum and their structure, are primary issues in the study of hadron physics. In particular, many candidates of exotic hadrons have recently been found near the threshold of hadronic channels [1, 2]. Extraction of such resonance information is an essential and challenging task. However, many of the existing analyses of...
The study of b-baryon decays are sensitive probes of New Physics through the study of branching fractions, CP asymmetries and angular measurements. Additionally, measurements of spectroscopy can provide valuable experimental input for QCD. The LHCb experiment has collected a large dataset and features excellent detector performance. This provides the LHCb with unprecedented capabilities of...
We present a computational investigation of a problem of hadron collisions from recent years, that of baryon anticorrelations. This is an experimental dearth of baryons near other baryons in phase space, not seen upon examining numerical Monte Carlo simulations.
We have addressed one of the best known Monte Carlo codes, Pythia, to see what baryon (anti)correlations it produces, where they are...
Hamiltonian effective field theory (HEFT) provides a powerful method by which we can extract physical information about the nature of baryon excited states, using both experimental data and lattice simulations as a function of quark mass. In particular, we have found that both the $\Lambda$(1405) [1] and Roper [2] resonances are molecular in nature, with the states expected within the quark...
We apply the renormalization group procedure for effective particles (RGPEP) to the eigenvalue problem in QCD for only heavy quarks. We derive the effective Hamiltonian that acts on the Fock space by solving the RGPEP equation up to second order in powers of the coupling constant. The eigenstates that contain three quarks and two or more gluons are eliminated by inserting a gluon-mass term in...
Meson photoproduction is a helpful tool for studying baryon resonances thanks to many possibilities of final-state meson-baryon combinations, e.g., $\pi N$, $\eta N$, $\omega N$, or multi meson final states.
In addition, the spin information of intermediate resonances can also be obtained by utilizing the high polarization of a photon beam.
The $\pi N$ final states can couple to both I = 1/2...
During the last decades, numerous experiments were performed with the aim of understanding meson photoproduction on light and heavy nuclei. Meson production on light nuclei, such as the deuteron or helium isotopes, allows one to access the baryon resonances produced on the nucleon. Photoproduction on heavier targets is well-suited for the understanding of possible modifications of hadrons,...
High-energy electrons and photons are a remarkably clean probe of ha-
dronic matter, essentially providing a microscope for examining atomic nu-
clei and the strong nuclear force. One of the most striking phenomena of
Quantum Chromodynamics (QCD) is the formation of the nucleon out of
massless gluons and almost massless quarks. This system of confined quarks
and gluons serves as the basic...
We present the spectrum of positive-parity baryons composed of light and heavy quarks. Our analysis is provided by a symmetry preserving Schwinger-Dyson Bethe-Salpeter Equation
(SDBSE) approach of a vector-vector contact interaction model. Our computations include the results using two different sets of parameters: one used to compute observables of light quarks, where the QCD-coupling is...
We solve the structure of baryons in a nonperturbative approach in the framework of light-front Hamiltonian, named Basis Light-front Quantization (BLFQ). We apply BLFQ to study the structure of the nucleon and the heavy baryons containing one strange or charm quark. I will show the resulting observables such as the form factors and various parton distribution functions characterizing the three...
I review the current status on baryon-baryon interactions such as nuclear forces in lattice Quantum ChromoDynamics (QCD), using the HAL QCD potential method. I first show results on HAL QCD potentials between nucleons (proton and neutron, denoted by $N$) in various cases, including preliminary results at the almost physical pion and kaon masses and exploratory studies on three-nucleon...
Effective chiral Lagrangian of deltas, nucleons and pions in external gravitational field and the corresponding energy-momentum tensor will be considered. Gravitational form factors of the deltas and their relation to internal forces will be discussed.
During the last few years, an unexpected emergent approximate symmetry has been observed in Euclidean correlation functions computed on the lattice. This chiral spin synnetry, once combined with isospin symmetry, is larger than the well-known chiral symmetry, and emerges dynamically in a range between the chiral crossover and roughly three times the crossover temperature. This can only happen...
We study the $\Omega(2012)$ which was measured in the Belle experiment. We conduct a study of the interaction of the $\bar K \Xi^*$, $\eta \Omega$($s$-wave) and $\bar K \Xi$($d$-wave) channels within a coupled channel unitary approach. We also present a mechanism for $\Omega_c \to \pi^+ \Omega(2012)$ production through an external emission Cabibbo favored weak decay mode, where the...
CP violation tests of hyperon-antihyperon pairs at BESIII
With the large datasets on 𝑒+𝑒−-annihilation at the 𝐽/𝜓 and 𝜓(3686) resonances collected at the BESIII experiment, multi-dimensional analyses making use of polarization and entanglement can shed new light on the production and decay properties hyperon-antihyperon pairs. In a series of recent studies performed at BESIII, significant...
While hadronic structure is experimentally probed by processes such as DIS and DVCS, both lattice and continuum techniques are employed to corroborate such results from a theoretical perspective. On the continuum side, the Fadeev equations provide a fully covariant approach to three body interactions convenient for describing three quark hadronic states. However, the four-spacetime-dimensional...
New relations between the electromagnetic/gravitational local spatial densities and corresponding form factors for various spin systems will be considered. It will be shown how traditional densities in the Breit frame emerge from a static approximation of the matrix element of corresponding local operators. Interpretation, advantages and disadvantages of the new and traditional definitions...
I give an overview of (some of) the different analysis tools and PWA approaches used to extract the spectrum of $N^*$ and $\Delta^*$ states from experimental data. Differences and similarities, e.g. in the construction of the amplitude, will be illustrated and I will show selected recent results.
We present an approach that allows one to obtain information on the compositeness of molecular states from
combined information of the scattering length of the hadronic components, the effective range, and the binding
energy. We consider explicitly the range of the interaction in the formalism and show it to be extremely important
to improve on the formula of Weinberg obtained in the limit...
We report on our studies of the forward virtual Compton scattering (VVCS) off a deuteron and the two-photon-exchange corrections to the $S$-levels in muonic ($\mu$D) and ordinary (D) deuterium within the pionless effective field theory (EFT). The spin-independent deuteron VVCS amplitudes are evaluated up to next-to-next-to-next-to-leading order (N3LO) for the longitudinal and next-to-leading...
The High Acceptance DiElectron Spectrometer (HADES) is a versatile detector with particular focus on dielectron measurements in pion, proton, deuteron and (heavy-) ion-induced reactions using proton or nuclei targets and SIS-18 beams with energies of up to 4.5 GeV/nucleon. Its excellent particle identification capabilities also allow for the investigation of hadronic observables.
The excess...
Data on the photo- and electroproduction of different hadrons provide access to the spectrum of excited baryons and its properties. Recent results from the Julich-Bonn-Washington model will be presented, including extensions to the electroproduction of pions and η mesons. The amplitudes and resonance properties obtained through this phenomenological analysis can serve as a point of comparison...
Obtaining a physically well-founded theoretical description of hadrons across energy scales is of high importance for the extraction of precision quantities such as hadronic contributions to the Lamb shift or the impact of neutrino-nucleon interactions on neutrino oscillation experiments. However, the strong force behaves remarkably differently at high and low energies: effective field...
Single and double pion electroproduction results off bound nucleons will be presented and the path from exclusive to quasi-free cross sections will be laid out. Their impact on guiding us towards a comprehensive QCD theory will be highlighted by recent and anticipated results as well as potentially available opportunities in the near future.
The proton mass is an emergent feature of QCD, as is the mass of the meson. Emergence of hadron mass provides the basic link between theory and observables. This presentation will sketch some of the theoretical developments in the use of Continuum Schwinger methods on mesons, focusing mainly on their parton distribution functions.
It is widely accepted nowadays that gluons, while massless at the level of the fundamental QCD Lagrangian, acquire an effective mass through the non-Abelian implementation of the classic Schwinger mechanism. The key dynamical ingredient that triggers the onset of this mechanism is the formation of composite massless poles inside the fundamental vertices of the theory. These poles enter in the...
Progress in understanding any aspect of nature is a "conversation" between measured quantities and theoretical models. As experiments get more accurate and sophisticated, models describing their results require to be more accurate and sophisticated; as new models are conceived, new experiments require to be performed to confirm or falsify predictions. Light baryon spectroscopy is no exception...
Measurements of correlations between particle pairs with low relative momentum via femtoscopy in pp collisions have been recently demonstrated to be very sensitive to the effects of the final-state strong interaction. Such studies face now a new challenge with the extension for the first time to three-body systems. The presented results are obtained using high-multiplicity pp collisions at...
Spontaneous breaking of the chiral symmetry plays a major role in generation of the hadron mass. It is predicted that the broken symmetry is partially restored even at normal nuclear density, and results in a measurerable difference in hadron mass.
J-PARC E16 has been proposed to measure such a change of vector mesons in nuclear medium at J-PARC Hadron Experimental Facility. It will measure...
Nucleon-nucleon interaction is studied within chiral effective field theory at next-to-leading order in the chiral expansion.
The leading order interaction is resummed non-perturbatively,
whereas the next-to-leading-order terms are taken into account in a perturbative manner.
Explicit renormalizability of such a scheme is analyzed in several important cases. The possibility to absorb the...
A recent measurement of coherent $\pi^0$ photoproduction on Pb leads to a most accurate determination of the neutron skin, constraining nuclear matter Equation of State (EoS) at around $\rho \sim 1\rho_0$. A natural next step is elucidating the nuclear EoS at higher densities to tune our understanding of the most violent process in the Universe - neutron stars mergers. It was demonstrated that...
Semi-Inclusive Deep Inelastic Scattering on nuclei offers a new way to gain microscopic information about the mechanisms of parton propagation and hadron formation in QCD. The interactions with the nuclear medium of the partonic and hadronic participants in the hadronization process can reveal features of that process at the femtometer distance scale. New data from CLAS on baryon hadronization...
In this talk, I will illustrate an alternative approach to Luscher’s formula for extracting the hadron-hadron interaction from finite volume energy levels. The framework includes three ingredients, plane wave basis expansion, effective field theory (EFT) and eigenvector continuation. With the plane wave basis, we can include the partial wave mixing effect in the cubic box more naturally than...
The quark mass dependence provided by Lattice QCD results encodes valuable information about hadronic properties. Chiral Perturbation Theory (ChPT) predicts both the low momentum and light quark-mass dependence of hadronic quantities in a model independent way, being therefore well suited to analyze Lattice data. Relying on our calculation of the nucleon isovector axial form factor in...
I will address the prospects of using femtoscopy in high-energy proton-proton and heavy-ion collisions to learn about the low-energy $J/\psi$-nucleon interaction. This interaction is relevant to the problem of the origin of nucleon's mass. Femtoscopy is a technique that makes it possible to obtain spatio-temporal information on particle production sources at the femtometer scale through...
The focus of our program – and hence this contribution – is to recast lessons learned over the last half of the 20th Century regarding the structure of atomic nuclei (primarily a particle-based picture) into a forward leaning 21st Century (field-theory-based framework) in anticipation that this will encourage the establishment of a natural bridge between the low-energy and medium-to-high...
Introduced more than two decades ago, Generalised Parton Distributions (GPDs) have been deeply studied theoretically as they offer the unique opportunities to i) probe the multidimensional structure of the nucleon in coordinate space, and ii) collect experimental information regarding the energy-momentum tensor of hadrons. Thus, high-precision facilities such as Jefferson Lab present dedicated...
The advent of the Electron-Ion Collider (EIC) is pushing the frontiers of hadron physics. Importantly, generalized parton distributions are expected to be accessible within an unprecedented accuracy. This work takes advantage of this context to present the first exploratory study on the access of pion GPDs at the EIC. Relying on state-of-the-art models for the pion's GPDs, we tackle the effect...
Hadrons are strongly interacting particles composed of quarks and gluons and described by Quantum Chromodynamics (QCD). Their internal structure can be described in terms of structure functions that encode, for example, the momentum and spin distributions of their constituents. Parton distribution functions (PDFs), for example, describe the quark and gluon momentum distributions inside a...
In this talk we will give a short overview of multi-dimensional parton distributions (TMDs, GTMDs...) and Soft Collinear Effective Theory (SCET). This will be used to explain the factorization process of the cross-section of an exclusive Double Drell-Yan and to show how this leads to the appearance of GTMDs.
We study the excitation function of the low-lying charmonium states: $J/\psi$, $\psi(3686)$ in $p$, $\pi$ and $\bar p$, Au collisions taking into account their in-medium propagation. The time evolution of the spectral functions of the charmonium state is studied with a BUU type transport model. We calculated the charmonium contribution to the dilepton spectrum. We study how the short range...
I will discuss the effects of chiral symmetry breaking in the hadron masses. This is accomplished by separating the four quark operators appearing in the vector and axial vector meson sum rules into chiral symmetric and symmetry breaking parts. We then identify each part from the fit to the rho and a1 meson masses, which form chiral partners. By taking the chiral symmetry breaking part to...
There has been recent, significant, advances in the determination of the hadron spectrum. Current efforts have focused on the development and application of finite-volume formalisms that allow for the determination of scattering amplitudes as well as resonance behavior in coupled channel systems. I will review some of these recent developments and outline future directions of research.
I will summarize advances on calculations of hadron spectrum and structure observables using functional methods such as Dyson-Schwinger and Bethe-Salpeter equations. Systematic improvements in this approach have made it possible to address a wide range of problems from the baryon excitation spectrum to multiquark spectroscopy, form factors, parton distributions and other areas. I will make a...
I will summarize advances on calculations of hadron spectrum and structure observables using functional methods such as Dyson-Schwinger and Bethe-Salpeter equations. Systematic improvements in this approach have made it possible to address a wide range of problems from the baryon excitation spectrum to multiquark spectroscopy, form factors, parton distributions and other areas. I will make a...
The two-particle momentum correlation function from high-energy nuclear collisions is beginning to be used to study hadron-hadron interaction. We discuss how the hadron-hadron interaction can be determined from the correlation function data. The experimental and theoretical situation of the baryon-baryon systems are reviewed focusing on the relation to the exotic hadrons. Finally, we discuss...
We have studied the low-lying nucleon resonances N(1530), N(1440), and Lambda(1405) and the relevant interactions with Hamiltonian effective field theory. Combined with the meson-nucleon scattering data and the lattice QCD simulations, and even the S11 pion photoproduction data, we obtain different structures of these resonances. Furthermore, we investigate the kaonic hydrogen and deuteron...
The so-called GPDs (Generalized Parton Distributions), sensisitive to the multi-dimensional "position" versus "momentum" of the nucleon's partonic constituents have been studied for many years at various facilities, for various kinematics. Most of the published measurements and most constraints to GPD models come from the DVCS (Deeply Virtual Compton Scattering) process. There is a growing...
We present results for the heavy baryon spectrum for ground and excited states with quantum numbers $J^P = 1/2^+$ and $3/2^+$ using functional methods in QCD. To this end, we reduce the three-quark Faddeev equations to two-body equations via the quark-diquark approach, where the baryons are treated as bound states of quarks and effective diquarks. The resulting Bethe-Salpeter equation amounts...
I will compare, in a pedagogical way, the traditional approach to heavy-lighty hadrons based on effective models of QCD,
to recent developments for heavy-light hadrons based on string theory. In particular, I will present predictions for the properties of recently discovered heavy-light tetraquarks and pentaquarks, based on the series of works [1-6].
[1] Y. Liu, M. A. Nowak, I....
The discovery of pentaquark states by the LHCb [1] revolutionized Hadron Physics, expanding the usual $qqq$ structure to four quarks and an antiquark. The first observations, detected in the $J/\psi p$ mass spectrum, showed two resonances, dubbed $P_c(4380)^+$ and $P_c(4450)^+$, close to $D^{(*)}N$ thresholds, which suggested a baryon-meson molecular nature in contrast to a compact pentaquark...
In this talk, I will discuss the hidden-charm pentaquarks with and without strangeness from the hadronic molecular point of view. I will show that the LHCb data can be well described under this picture by constructing an effective field theory for the interactions between $\Sigma_c^{(*)} \bar D^{(*)}$. Predictions of many more hidden-charm and double-charm molecular pentaquarks will be...
During the last few years the LHCb collaboration has detected a series of hidden-charm pentaquarks, the most recent one being the $P_{\psi s}^{\Lambda}(4338)$, which has the quantum numbers of a $\Lambda$ baryon. Most of these pentaquarks are close to a meson-baryon threshold and have been readily interpreted as bound (or molecular) states. Here we explore what are the consequences of the...
The flow of information in high-energy collisions has been recently investigated by various groups. Entanglement entropy of the proton becoming classical information entropy of pdfs, jet splitting affecting entropy, or the entropy in hadron decays have already been reported in the literature. Here we examine aspects of fragmentation functions in this context, including their entropy as...
The search for the QCD critical point (CP), and the study of quark-hadron phase transition (and vice-versa), at finite baryon density and high temperature, is the main task in contemporary relativistic ion collision experiments. Fluctuation analysis with global and local measures is the basic tool to achieve this goal. Local density fluctuations are directly related to the critical behaviour...
The M2 beamline at the CERN/SPS can provide both muon and hadron beams with energy up to few hundred GeV. A new fixed-target experiment, AMBER (Apparatus for Meson and Baryon Experimental Research), explores this versatility by addressing several aspects of the so-called Emergence of Hadron Mass mechanism. The experimental program, started in 2021, includes in its already approved phase-I: the...
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+ --> pi+ nu nu decay, based on 20 candidates.
The radiative kaon decay K+ → pi0e+vg (Ke3g) was studied with a data sample of O(100k) Ke3g candidates with sub-percent background contaminations recorded in 2017-2018....
Hadronic resonances, due to their short lifetimes, are useful to probe the properties of the hadronic phase in ultra-relativistic heavy-ion collisions. Indeed, regeneration and rescattering processes occurring in the hadron gas modify the measured yields of hadronic resonances and can be studied by measuring resonance yields as a function of system size and by comparing to model predictions...
The search for predictive capabilities in the study of hadronic reactions and nuclear structure from the Standard Model, which describes the strong and electroweak interactions in nature, is a defining challenge that bridges nuclear and particle physics. In this talk I will present some of the progress made in that direction by calculations using Lattice QCD (LQCD), a systematically improvable...
The vast bulk of visible mass emerges as a consequence of nonperturbative dynamics within the strong interaction sector of the Standard Model. The past decade has revealed the three pillars of this emergent hadron mass (EHM); namely, a nonzero gluon mass-scale, a process-independent effective charge, and dressed-quarks with constituent-like masses. Contemporary theory is now exposing their...
Outstanding vertexing performance and low-background environment are key enablers of a systematic Belle II program targeted at measurements of charm baryon lifetimes. Recent results from measurements of the $\Lambda_c$ and $\Xi_c$ baryon lifetimes are presented. The former result is the most precise to date.
For decades an assortment of quark models and more recently lattice QCD calculations have predicted many more Cascade baryon states than have been experimentally observed. Furthermore, SU(3) flavor symmetry indicates that there should be a Cascade partner for every $N^*$- and $\Delta ^*$- resonance. The spectrum of the doubly strange $\Xi$ baryons is poorly known and only a few states have...
The status and the project of a low-energy Chinese electron-ion collider (EicC) is briefly introduced. Measurements of pseudoscalar meson structures are important for the fully understanding of the emergent hadron mass problem. The leading baryon tagged DIS process and the Sullivan process are the useful tools to obtain the form factor and structure function information of the pion (and the...
We present recent results on in-medium spectral functions of mesons with a particular emphasis on the rho(770) vector meson and the a1(1260) axial-vector meson in nuclear matter, as well as on the resulting thermal dilepton rate. As an effective description of the thermodynamics and the phase structure of nuclear matter we use a chiral baryon-meson model, taking into account the effects of...
We summarise recent theoretical results on the QCD phase diagram and the properties
of hadrons at finite temperature and chemical potential based on a combination of
lattice QCD and Dyson-Schwinger equations. We discuss the silver blaze property
of mesons with different quantum numbers along the zero-T-finite-mu-axis and assess
the influence of meson and baryon fluctuations on the...
We study the interaction of meson-baryon coupled channels carrying quantum numbers of $\Omega_{cc}$ , $\Omega_{bb}$ and $\Omega_{bc}$ presently under investigation by the LHCb collaboration. The interaction is obtained from one extension of the local hidden gauge approach to the heavy quark sector that has proved to provide accurate results compared to experiment in the case of $\Omega_{c}$ ,...
By exploring the interactions among mesons and baryons, in a coupled-channels approach, for the heavy-quark sector (charm and bottom), we investigate the dynamical generation of singly Ωc/Ωb and doubly Ξcc, Ξbc, and Ξbb heavy-quark baryon resonances. The interactions describing the meson-baryon transitions among the relevant channels are evaluated considering the vector meson exchange...
Exotic, BSM components of the weak interaction will be probed in the BRAND
experiment via measurement of correlation coefficients of neutron β-decay.
Ultimately, the BRAND detection setup will be able to provide precisely measured
eleven correlation coefficients (a, A, B, D, H, L, N, R, S, U, V). Among them, seven (H,
L, N, R, S, U, V) are dependent on the transverse electron...
Exotic spectroscopy is a hot topic. In this review talk, the last main experimental discoveries will be presented and then the main theoretical interpretations will be discussed.
Finally, some results of which I am also one of the authors will be presented and discussed.
The exotic hadrons have a different internal structure from the ordinary hadrons with $qqq$ or $q\bar{q}$. $T_{cc}$, observed by the LHCb Collaboration last year, is considered as the exotic state with $cc\bar{u}\bar{d}$ [1]. One of the possible internal structures of the exotic hadron is the hadronic molecule state which is a weakly bound state of hadrons. The weight of the hadronic molecule...
Theoretical calculations of neutrino-nucleus scattering cross sections are critical for the success of the accelerator neutrino program, as experiments use nuclear targets in their detectors. I will present a nuclear quantum Monte Carlo protocol suitable to compute quasi-elastic lepton-nucleus inclusive scattering for moderate momentum transfer accurately. To tackle the high-momentum regime, I...
In the context of lepton flavor universality violation (LFUV) studies, we study different observables related to the $b\to c\tau \bar{\nu}_\tau$ semileptonic decays. These observables are expected to help in distinguishing between different NP scenarios. Since the $\tau$ lepton is very short-lived, we consider three subsequent $\tau$-decay modes, two hadronic $\pi\nu_\tau$ and $\rho\nu_\tau$...
Understanding of the strong interaction dynamics that underlie the emergence of hadron mass (EHM) represents a challenging open problem in the Standard Model. New opportunities for gaining insight into EHM will be presented from the results on the evolution of the nucleon resonance electroexcitation amplitudes (i.e. the gvpN* electrocouplings) with photon virtuality Q2 determined from...
The nucleon self-energy is calculated in SU(2) covariant chiral perturbation theory to study the pion mass dependence of the nucleon mass up to chiral order $O(q^6)$, i.e., including two-loop diagrams.
The contributions of the diagrams are expressed by a small set of (scalar) master integrals, which are evaluated by means of the chiral expansion in $d$ dimensions, using the strategy of...
We propose a systematic approach to study the nucleon-nucleon interaction by applying time-ordered perturbation theory (TOPT) to covariant chiral effective field theory. Diagrammatic rules of TOPT, for the first time, are worked out for particles with non-zero spin and interactions involving time derivatives. They can be applied to derive chiral potentials at any chiral order. The effective...
We present a new model for electroweak pion production that is an extension of MAID, the unitarized isobar model for pion photo- and electroproduction on the nucleon. At low energy the model includes the most prominent nucleon and $\Delta$ resonances, as well as the non-resonant contributions that are unitarized in each partial wave by the respective $\pi$N-phase. At high energy we account for...
In this talk we will discuss our recent works (2201.08253 and 2207.08563) in which we make analyses of several X and Z states. In the first part of the talk, we present a combined study of the BESIII spectra in which the Zc(3900) and Zcs(3985) states are seen, assuming that both are SU(3) partners. In the second part, a step further is taken and we analyze the full heavy quark spin and light...
An improvement to the widely used distillation technique for hadron spectroscopy is presented in the context of meson spectroscopy. Introducing meson profiles in distillation space and optimizing them for the different operators and states of interest significantly increases the overlap between the created states and the energy eigenstates at no considerable extra cost. We show results...
The talk will review recent lattice spectroscopic studies of baryons, such as the calculation of the spectrum of heavy flavored baryons, the meson-nucleon scatterings related to Delta baryon and nucleon excited states, as well as new calculations of the pion-nucleon sigma term and the nucleon mass structure. The progress in studying diquarks in baryons will also be introduced.
Sending abstract by end of this week
In the past two decades there has been tremendous progress in the theoretical and experimental investigation of multiquark states, which has expanded our understanding of what a “hadron” is. Experimental evidence suggests that Nature does not only form “conventional” hadrons such as mesons as quark-antiquark states and baryons as three-quark states, but also more exotic combinations such as...
The spectroscopy of charmonium-like states together with the spectroscopy of charmed and strange baryons is discussed. It is a good testing tool for the theories of strong interactions, including: QCD in both the perturbative and non-perturbative regimes, LQCD, potential models and phenomenological models [1, 2, 3]. An understanding of the baryon spectrum is one of the primary goals of...
During this talk, I will describe the research of Thomas Jefferson National Accelerator Facility (TJNAF, or JLab) where we explore the nature of QCD and matter at its most fundamental level of quarks and gluons. Understanding the amazing world inside a nucleon requires tremendous technical capabilities embodied in the large accelerator facility and advanced detector technology known as CEBAF...
First hidden-charm pentaquark candidate with strangeness, $P_{\psi s}^\Lambda(4338)$, was recently discovered in $B^-\to J/\psi\Lambda\bar{p}$ by the LHCb Collaboration. $P_{\psi s}^\Lambda(4338)$ shows up as a bump at the $\Xi_c\bar{D}$ threshold in the $J/\psi\Lambda$ invariant mass ($M_{J/\psi\Lambda}$) distribution. The $M_{J/\psi\Lambda}$ distribution also shows a large fluctuation at the...
Why does our Universe contain so much more matter than antimatter? If not fine-tuned in the Big Bang, the abundance of matter must have been dynamically generated, e.g. through Baryogenesis. This, however, requires the existence of processes that violate charge conjugation and parity symmetry (CP). Hyperon decays have been proven a powerful diagnostic tool to study CP violation, thanks to the...
The spectroscopy of charmonium-like mesons with masses above the 2_mD open charm threshold has been full of surprises and remains poorly understood [1]. The currently most compelling theoretical descriptions of the mysterious XYZ mesons attribute them to hybrid structure with a tightly bound cc\bar diquark [2] or cq(cq)\bar tetraquark core [3 - 5] that strongly couples to S-wave DD\bar...
The scaling property of large-$p_\perp$ hadron suppression, $R_{\rm{AA}}(p_\perp)$, measured in heavy ion collisions at RHIC and LHC allows for the determination of the average parton energy loss $\langle \epsilon \rangle$ in quark-gluon plasma produced in a variety of collision systems and centrality classes. Rescaling $\langle \epsilon \rangle$ by the particle density allows for the...
We develop a model for the production of the $P_c$ states observed at LHCb in $\Lambda_b\to J/\psi p K^-$ decays. With fewer parameters than other approaches, we obtain excellent fits to the $J/\psi p$ invariant mass spectrum, capturing both the prominent peaks, and broader features over the full range of invariant mass. A distinguishing feature of our model is that whereas $P_c(4312)$,...
We study pseudoscalar meson properties and compute the $\gamma^{*}\gamma \rightarrow \pi^0,\eta,\eta'$ transition form factor in the framework of the Dyson-Schwinger equations (DSE) and Bethe-Salpeter equations (BSE), using a momentum-independent contact interaction. The contact interaction is capable to describe the observable properties, but produce a transition form factor whose evolution...
Lattice QCD computations of generalized parton distributions (GPDs) have been traditionally done in the Breit frame, where the transferred momenta is symmetrically distributed between the incoming and outgoing hadron. This set up demands a separate calculation for each momentum transfer value. This talk will outline a Lorentz covariant formalism to carry out lattice QCD computation of GPDs...
Following simple large Nc arguments and perturbative QCD constraints complemented with uncertainty estimates based on the idea of meson dominance and the half-width rule, we describe the pseudoscalar form factors of the nucleon. We analyze their implications in the space-like region at intermediate and low energies and compare to recent lattice QCD determinations. Our analysis allows for a...
Building 3D maps of the internal structure of the proton allows us to explore the inner structure of matter and and to learn about the dynamics its fundamental constituents.
I will give a brief overview of tcollinear and TMD factorization theorems, which are at the basis of the predictive power of QCD, and an overview of the state of the art of TMD phenomenology, focusing on a personal...
I will discuss how quarkonium production can be used to probe transverse-momentum-dependent functions (TMDs), both in $pp$ and $ep$, paying spacial attention to the role played by a new type of non-perturbative functions, the so-called TMD shape functions.
The doubly heavy $\Omega_{cc}$ baryon represents a distinctive three quark system because they contain a strange light quark in the combination of two charm quarks. There are new decay modes and excited states seen in doubly charmed baryons by CLEO, LHCb and many other experiments and they have attempted to identify the doubly heavy baryons, but only a few states have been discovered so...
We study radiative corrections to neutron beta decay within heavy-baryon chiral perturbation theory. As it was recently shown, a few electromagnetic and electroweak low-energy effective couplings are not known in the literature. We relate these low-energy constants to correlation functions of vector and axial-vector currents. Such relations allow us to demonstrate explicitly scheme and scale...
This talk will present some recent hadron physics results obtained from the MAMI (Germany) and JLAB (USA) intense photon beam facilities. New data which constrains our understanding of the hyperon-nucleon interaction will be presented, obtained via photoproduction and rescattering processes in light nuclear targets. In addition, the current status and future plans of the programme aiming to...
In recent years, a breakthrough was made in calculating the Bjorken‐x dependence of PDFs in lattice QCD by using large‐momentum effective theory
(LaMET) and other similar frameworks. The breakthrough has led to the emergence and rapid development of direct calculations of Bjorken-x dependent structure. In this talk, I will review the recent progress made in lattice QCD and future challenges.
Exact solutions for energy spectra and eigenstates for Tetraquarks are found by using an infinite dimensional algebraic method. The Interacting Boson Model, as proposed by Arima and Iachello [1], includes two types of bosons with angular momentum L = 0 (s bosons) and L = 2 (d bosons) in a two-level system. Exact eigen-energies and the corresponding wavefunctions of an interacting four-level...
$\Omega_c^{0}$ baryon is the center of attraction for many researchers after the discovery of different states all together in the single decay $\Omega_c^0 \to \Xi_c^+ K^-$. These states are $\Omega^{0}_c(2695)$, $\Omega^{0}_c(2770)$, $\Omega^{0}_c(3000)$, $\Omega^{0}_c(3050)$, $\Omega^{0}_c(3067)$, $\Omega^{0}_c(3090)$ & $\Omega^{0}_c(3120)$. Thus, we investigate the S-wave of $\Omega^0_{c}...
The search for new particles in the low mass range is motivated by new hidden sector models and dark matter candidates introduced to account for a variety of experimental and observational puzzles: the small-scale structure puzzle in cosmological simulations, anomalies such as the $4.2\sigma$ disagreement between experiments and the standard model prediction for the muon anomalous magnetic...
Dyson-Schwinger equations (DSEs) is employed successfully to provide a unified explanation for the properties of hadrons with $0-3$ heavy quarks, viz. from the lightest (almost) Nambu-Goldstone bosons to triply heavy baryons, e.g.. Each semileptonic transition is conventionally characterized by the value of the dominant form factor and we present predictions for transition form factors and...
In QCD, gluons acquire an effective mass through the Schwinger mechanism, which is triggered by the dynamical formation of longitudinally coupled massless bound-state poles. The presence of these poles leaves smoking gun signals in the fundamental Ward identities, which are displaced by contributions of the Bethe-Salpeter amplitudes of the massless bound states. This displacement can be...
we study the radial and orbital masses of singly beauty baryons. The hypercentral Constituent Quark Model(hCQM) is employed with screened potential. The calculated mass spectra are compared with the latest results of LHCb collaboration and CMS collaboration as well as with the other theoretical approaches and are found to be in good accordance. The single-pion strong decay widths are...
Production of strange quarks in relativistic heavy-ion collisions is not only used as a signature of QGP formation but also as a diagnostic tool. Strange quarks and antiquarks are produced via strong interactions in the QGP medium and are not present in ordinary matter. The reason is that they promptly undergo decay via weak interactions as soon as they are produced. Additionally, the mass of...
Understanding the structure and dynamics of the proton constitute an important remaining challenges in hadron physics. From the theory side, one of the challenges is to extract from Lattice QCD calculations, performed in Euclidean space, Minkowskian quantities such as the proton parton distribution function. It is difficult to do the inversion of Euclidean quantities back to the corresponding...
We used a diffusion Monte Carlo technique to describe the properties of fully-heavy compact arrangements (no dibaryon molecules) including six quarks and no antiquarks within the framewok of a constituent quark model. Only arrangements whose wavefunctions were eigenvectors of $L^2$ with eigenvalue $ℓ = 0$ were taken into account, what means that we only considered the subset of all the...
The inter-quark potentials diverge at large distance because of the color confinement of quarks. The inter-hadron potentials, on the other hand, vanish at large distance, because the interaction range is limited by the inverse pion mass.
What then is the effect of the coupling to the inter-hadron potentials in the inter-quark potentials and vice versa?
We consider, in this talk, the...
Recent results and future plans at J-PARC on baryon-baryon interaction studies are presented.
We recently observed several new events of double-strange hypernuclei in the emulsion-counter hybrid experiment (E07) [1]. Observed events indicate a rather deep binding energy of $\Xi$ in the $^{14}$N nucleus. One of the events is interpreted as a bound state of $\Xi$ in the nuclear 0s orbit,...
Detailed exploration of the spectrum and structure of excited nucleon states from different exclusive reactions in terms of their electro-excitation amplitudes (or $\gamma_vpN^*$ electrocouplings) as a function of four-momentum transfer $Q^2$ is essential to probe the nature of the non-perturbative strong interaction responsible for their generation. Studies to determine the electrocouplings...
A relativistic model of independent quarks based on Dirac equation with an equally mixed scalar-vector square root confining potential is used to compute the quark core contributions to study the static properties like magnetic moments and charge radii of the Δ baryons with spin $\frac{1}{2}$ and spin $\frac{3}{2}$. The results obtained with inclusion of appropriate centre-of-mass motion...
The large-$N_c$ and constituent approaches are two well-known tools to probe QCD at the hadronic level. In the large-$N_c$ approach, as developed by 't Hooft and Witten, one considers hadrons in the gauge group $SU(N_c)$, with $N_c (\rightarrow \infty)$ the number of colour, and where quarks live in the fundamental representation of the group. Then, observables can be expanded in powers of...
The total decay widths of charmed baryons, including all the possible open-flavor decay channels, are calculated through the $^3P_0$ model. Furthermore, we calculate the masses of the charmed-baryon up to the D-wave in a constituent quark model, using the three-quark and quark-diquark schemes. We use a Hamiltonian model based on a harmonic oscillator potential plus a mass splitting term that...
We present full QCD correlator data and corresponding reconstructed spectral functions charmonium and bottomonium. Correlators are obtained using clover-improved Wilson fermions on $N_f=2+1$ HISQ lattices. We use gradient flow to check whether it reduces cut-off and mixed action effects. Valence quark masses are tuned to their physical values by comparing the mass spectrum obtained from the...
We consider the chiral Lagrangian with nucleon, isobar, and pion degrees of freedom. The baryon masses and the axial-vector form factor of the nucleon are derived at the one-loop level.
We explore the impact of using on-shell baryon masses in the loop expressions. As compared to results from conventional chiral perturbation theory we find significant differences. An application to QCD...
The recent discoveries of the pentaquark, $P_C$, states and $XYZ$ mesons in the charmed quark sector has initiated a new epoch in hadron physics. The existence of exotic multi-quark states beyond the conventional three and two quark systems has been realised. Such states could manifest as single colour bound objects, or evolve from meson-baryon and meson-meson interactions, creating...
For nearly half a century the charge radius of the proton had been obtained from measurements of the energy levels of the hydrogen atom or by scattering electrons from hydrogen atoms. Until recently the proton charge radius obtained from these two methods, agreed with one another within experimental uncertainties. In 2010 the proton charge radius was obtained for the first time by precisely...
In this talk, I will discuss a novel framework to extract resonant states from finite-volume energy levels of lattice QCD and apply it to elucidate structures of the positive parity Ds resonant states nearby the DK and D*K thresholds. In the framework, the Hamiltonian effective field theory is extended by combining it with the quark model. The Hamiltonian contains the bare mesons from the...
The three-gluon vertex plays a central role in the infrared dynamics of Quantum Chromodynamics (QCD). Gluon self-interaction is the main difference between this theory and others like quantum electrodynamics (QED); namely its non-abelian nature. The appearance of a three-gluon vertex in the QCD Lagrangian is intimately linked to both asymptotic freedom and confinement in QCD. The study of its...
The status of recent theoretical research related to the behavior
of the $\phi$ meson in nuclear matter is reviewed, focusing on observables
that will be measured at the J-PARC E16 experiment, including
dilepton and $K^+K^-$ decay modes and their angular distributions.
The relation of these observables to fundamental properties of the strong
interaction and nuclear matter, such as...
We shall discuss novel results for the three-gluon vertex, based on the analysis of recent, extensive lattice quenched simulations, featuring a singular kinematical property of its dominant form factor that we denominated "planar degeneracy". On the ground of this property, one can apply to three-gluon vertex to unveil a distinctive signature of the mass generation mechanism in the QCD gauge sector.
We discuss the measurement of gluon transverse momentum distribution (TMD) in dijet and heavy hadron pair (HHP) production in semi-inclusive deep inelastic scattering. The factorization of these processes in position space shows the appearance of a specific new soft factor matrix element on top of angular and complex valued anomalous dimensions. We show in detail how these features can be...
We employ a powerful worldline formalism to uncover the role of the chiral anomaly in polarized deeply inelastic scattering in QCD at high energies and demonstrate simply that the anomaly dominates the proton's helicity in both Bjorken and Regge asymptotics. We independently confirm Veneziano's argument that the physics underlying topological mass generation in QCD (the UA(1) problem) is also...
Electric dipole moments (EDM) of fundamental particles provide powerful probes for physics beyond the Standard Model. Magnetic dipole moments (MDM) of baryons provide further information on the baryon substructure and represent experimental anchor points for tests of low-energy QCD models, related to non-perturbative QCD dynamics. These have not been experimentally accessible to date for the...
High-accuracy upsilon photoproduction data from EIC and EicC experiments will allow the measurement of the near-threshold total cross section of the reaction gamma + p --> upsilon + p, from which the absolute value of the upsilon-p-scattering length can be extracted using a vector-meson dominance model. For this evaluation, we used upsilon-meson photoproduction quasidata from the QCD approach...
