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- Indico Weeks View
10 October, 8:30 am: opening of the conference, 13 October 17:30: Closing of the conference.
The International Symposium on Physics in Collision is a conference series that began in 1981 in Blacksburg, Virginia, USA. The symposium program is composed mainly by review talks that reflect new results from experimental research with a main focus on particle physics, but also reporting from other areas like heavy ion, astroparticle and gravitational physics. In addition to that, the symposium invites as well shorter contributions in the form of poster sessions and parallel talk sessions on the above topics. Invited speakers will review and update key topics in particle physics and related topics in which new results have been published in the last year or are reasonably expected to be so before the next symposium. The aim of presentations is to encourage informal discussions of new experimental results and their implications. The topics at the symposia cover a wide range of physics subjects from accelerator-based particle physics to astroparticle physics.
In 2023 the conference will be hosted in the University of Tarapaca, in Arica, Chile, the city of "Eternal Spring " and an exceptional location on the Pacific Ocean.
Charla pública en inglés y español.
Public talk in English and Spanish.
The status of the LHC Run 3 and the results from ATLAS and CMS based on the data collected during 13.6 TeV pp runs at the LHC are presented.
Properties of the standard model Higgs boson
Rare processes and search for new phenomena through Higgs bosons
Top quark production, properties and rare processes
With the discovery of neutrino oscillations and demonstrating that neutrinos have a mass, the Standard Model of particle physics is to be insufficient to describe it. It is too small to be explained with the Standard Model, hence other mass creating mechanisms must exist. In some of these models the neutrino is its own anti-particle. The practical only way to prove this Majorana nature of the neutrinos is neutrinoless double-beta decay. Experiments designed to search for this decay are probes into particle and nuclear physics beside accelerator-based experiments.
I will give an introduction about the physics of neutrinoless double beta-decays and overview on the techniques of the major efforts around the world. A number of experimental results now exclude neutrinoless double-beta decay up to 10$^{26}$ years. The results start to reach a region where the neutrino mass hierarchy model can have significant impact on the interpretation of results. I will show what requirements are needed to push further with the goal to completely cover one of two hierarchy models. I will give an overview on how the next-generation of ton-scale sized experiments approach the experimental challenges.
Neutrino oscillations are the leading mechanism that successfully explain the neutrino flavor transitions observed at dedicated detectors from several sources of neutrinos like the Sun, from cosmic rays interacting with the Earth atmosphere, and neutrinos from artificial sources such as the ones produced in reactor and accelerator-based experiments. This wealth of data is well described by neutrino oscillations within the three-active neutrino framework. In this talk the current status of this framework will be reviewed. The current precision of the measured oscillation parameters and the "known unknowns" will also be discussed. This will serve as an introduction to the goals and challenges that the future neutrino program will have to face.
Nuclear fusion reactions within stars generate the energy and forge the elements observed throughout the Universe. These reactions transform primordial hydrogen and helium remnants from the Big Bang into a diverse array of elements. Nuclear astrophysics provides unique insights into the nuclear processes involved in astrophysical environments and responsible for the nucleosynthesis of the elements. Studying these processes is challenging due to the small cross section in the relevant energy range, known as the Gamow window, and the very low counting rate at such low energy.
By investigating these reactions, primordial nucleosynthesis as well as the composition and evolution of stars can be unraveled, shedding light on the intricate mechanisms behind the chemical evolution of the Universe. Complimentary approaches involving both direct and indirect measurements enable the investigation of nuclear reactions in the Gamow window, often exploiting particular conditions.
This talk highlights the most significant methods of nuclear astrophysics and shows some of the ongoing experimental efforts in unraveling the secrets of nuclear reactions that shape our Universe.
Highlights from the cosmic rays observed with the Pierre Auger Observatory
Research on neutrino physics in currently advancing at an impressive pace thanks to the great efforts on different fronts, including high energy physics, cosmology and astrophysics. In particular, the study of neutrino oscillations and interactions with matter concentrates important attention from the community, manifest from the remarkable experiments that have collected data and measured the parameters governing these phenomena with an increasing precision. In addition, looking for improving and completing our understanding of the neutrino flavor-changing process, new experiments are being proposed and/or in construction stages, which would also provide opportunities to explore other relevant aspects of neutrino physics and beyond. In this talk I will present a review of some of the recent results obtained by the experiments studying neutrinos produced by accelerator facilities and detected after traveling long distances, and explore some aspects of the proposed experiments currently in the construction phases.
I will present the recent experimental results on Charm hadron decays.
Hadron spectroscopy is essential in improving our understanding of the nonperturbative regime of QCD and to reveal the mechanism of color con?nement. Recent experimental results in light hadron sector and heavy hadron sector from LHC experiments, BESIII, Belle II and GlueX will be presented.
Since the discovery of X(3872), Belle has been pioneering the exploration
of tetraquarks, QCD bound states beyond standard mesons and baryons. More
than a decade after the end of data taking, the Belle datasets are still
producing results in hadron spectroscopy, and have provided the
motivations for the first energy scan above the energy of the $\Upsilon(4S)$ peak, between 10.65 GeV and 10.81 GeV, taken by Belle II in November 2022. This talk will present recent results on searches for the hidden bottom transitions between $\Upsilon$(10750) and lower bottomonia, and measurements of the energy dependence of the $e^+e^-\rightarrow B^{(*)}\bar{B}^{(*)}$ cross section. In addition, we will show results of a search for resonant double charmonium bound states, done with Belle data, which gives insights on our future opportunities on this topic.
The MicroBooNE experiment employs an 85-ton active mass liquid argon time projection chamber to detect neutrinos from both the on-axis Booster Neutrino Beam (BNB) and off-axis Neutrinos at the Main Injector (NuMI) beam. One of the main goals of MicroBooNE is to investigate MiniBooNE low energy excess/anomaly. In this talk, we will present the recent results from MicroBooNE’s low energy excess (LEE) search based on a search of single photons in MicroBooNE and a series of three independent analyses targeting different final-state topologies which look for an anomalous excess of electron neutrino events. We will also discuss the interpretation of these results in the context of the 3+1 oscillation framework under a light sterile neutrino model, as well as ongoing efforts for other BSM explanations of the MiniBooNE anomaly. Additionally, we will examine the impact of a degeneracy resulting from the cancellation of $\nu_e$ appearance and disappearance, and demonstrate that combining data from the BNB and NuMI beams, which have substantially different $\nu_e/\nu_\mu$ ratios, can break this degeneracy.
Neutrinos can teach us volumes about the fundamental makeup of our world as well as about the sources that produce them. The extremely intense and well-understood electron antineutrino flux emitted by the beta-decays of fission products in nuclear reactors is an excellent resource to study these elusive particles. This talk will describe the considerable progress achieved recently in the field of reactor neutrino physics and will review the exciting prospects that lay ahead, all with a focus on experiments located at km-scale baselines from their reactor core(s).
The third observing run of advanced LIGO, Virgo and KAGRA brought unprecedented sensitivity towards a variety of quasi-monochromatic, persistent gravitational-wave signals. Continuous waves allow us to probe not just the canonical asymmetrically rotating neutron stars, but also different forms of dark matter, thus showing the wide-ranging astrophysical implications of using a relatively simple signal model. In this talk, I will summarize recent results from searches for dark matter in the form of asteroid-mass primordial black holes, dark matter clouds that could form around rotating black holes, and even dark matter that could interact with the detectors themselves.
The Dark Energy Spectroscopic Instrument (DESI) is a fiber-fed, robotically-actuated galaxy redshift survey that has been in operation at Kitt Peak National Observatory near Tucson, Arizona, USA since mid-2021. DESI, which observes the growth of structure from the nearby universe out to a redshift of 3, is currently producing the largest catalog of gravity redshifts ever assembled. With an order of magnitude more statistics than any previous redshift survey, the instrument is designed to provide sensitive constraints on dark energy, cosmic inflation, modified gravity, and the sum of the neutrino masses. In this talk, we describe the performance of the DESI instrument, the status of the survey, and future results.
The discovery, in 2013, of a diffuse astrophysical neutrino flux by IceCube marked the beginning of neutrino astronomy. Since then, great efforts have been devoted to the search for cosmic neutrino sources. Although any neutrino source has been unambiguously identified, the neutrino high energy event candidate IC170922 triggered a multiwavelenght observation campaign providing a hint for neutrino emission from the blazar TXS 0506+056 and inaugurating the multi messenger astronomy.
Several other results have been provided by the IceCube Collaboration in the field of neutrino properties and astronomy. In June 2023, the IceCube Neutrino Observatory has produced the first image of the Milky Way using neutrinos providing evidence of high-energy neutrino emission from our Galaxy. The need for a complete coverage of the neutrino sky, especially in the muon channel that is the golden channel for neutrino astronomy, trigged the construction and installation of a neutrino telescope in the Northern hemisphere.
ANTARES was a 0.01 km3 underwater telescope that operated at 2400 m depth off shore Toulon for 12 years providing limits on several neutrino sources. The next generation underwater detector is KM3NeT that consists of two telescopes based on the same detection technology, currently under deployment in the Mediterranean Sea. ARCA, off-shore Sicily (Italy) is the km3 telescope devoted to neutrino astronomy while ORCA, off-shore Toulon (France) is devoted to neutrino properties. ARCA will provide an almost total coverage of the neutrino sky with unprecedented angular resolution thus enhancing the discovery potential for neutrino point-like sources. The GVD neutrino telescope is also under construction at lake Baikal (Russia). In this review results and perspectives of neutrino astronomy will be discussed.
Astroparticles open exciting new horizons in the realm of particle physics research by exploring energy regimes beyond the reach of traditional accelerators. The study of ultra-high-energy cosmic rays involves the observation of the air showers they generate in the atmosphere, offering a unique tool to investigate the most energetic particles in the Universe. The Pierre Auger Observatory, as the largest cosmic-ray air shower detector, employs an innovative hybrid approach that enables simultaneous monitoring of the longitudinal development of air showers in the atmosphere and the detection of particles at ground level. This methodology significantly enhances precision in characterizing air showers, driving advancements in cosmic-ray research. Despite these achievements, substantial uncertainties persist in modeling hadronic interactions at ultra-high energies. Results that are most relevant for elucidating the characteristics of hadronic interactions in the ultra-high energy regime will be presented.
AugerPrime, the ongoing upgrade of the Pierre Auger Observatory, has been designed to improve the sensitivity of ultra-high-energy cosmic ray (UHECR) measurements to a level that enhances the capabilities of the original design. An essential aspect of this upgrade is the installation of the Radio Detector (RD), which consists of antennas mounted on top of each of the 1660 water-Cherenkov detectors. These antennas possess polarizations aligned both parallel and perpendicular to the Earth's
magnetic field, making them sensitive to the detection of inclined showers. The key emphasis of the RD installation is its high sensitivity to the electromagnetic component of air showers, providing novel insights for reconstructing the primary mass, energy, and arrival direction of UHECR.
The Auger Engineering Radio Array (AERA) has been operational within the Pierre Auger Observatory for several years. Utilizing the collected data, it became possible to demonstrate the feasibility of radio detection, enabling the measurement of inclined showers with zenith angles from 60 to 84 degrees.
In this presentation, we provide an update on the status of the AugerPrime Radio Detector and offer an overview of the results obtained from AERA.
The Pierre Auger Observatory is the largest facility in the world devoted to the study of ultra-high-energy cosmic rays (UHERCs). Its hybrid design provides the ability to measure multiple mass-sensitive observables simultaneously as well as a calorimetric determination of the primary energy with unprecedented precision. With the completion of its Phase I, and after nearly 20 years of data collection, the Observatory has accumulated the world's largest exposure to UHERCs. In particular, mass-composition studies derived from data have played an important role in disentangling the origin and propagation of UHERCs. In this presentation, we provide an overview of the principal results of the composition analysis for energies from 0.1 EeV up to 100 EeV using data obtained by the fluorescence, surface, and radio detectors. Specific results are presented on mass trends from surface detector risetimes and the correlation between $X_{max}$ and signal amplitudes at the ground. Finally, future composition measurements will be discussed in the context of AugerPrime, the upgrade of the Observatory that started collecting data in 2022.
BESIII has collected 2.93, 7.33, and 4.5 fb^-1 of $e^+e^-$ collision data samples at 3.773, 4.128-4.226, and 4.6-4.7 GeV, which provide the largest dataset of $D\bar{D}$, $D_s^*D_s$, and $\Lambda_c\bar{\Lambda}_c$ pairs in the world, respectively.
For charmed mesons, we will report the updated measurements of $D_s^+\to \eta^{(‘)} e^+ \nu_e$, $D_s^+\to \tau^+ \nu_\tau$, and the form factor studies in $D_s^+\to\pi^+\pi^- e^+ \nu_e$. In addition, we will report the amplitude analyses of Cabibbo-favored and -suppressed $D_s$ decays, including the observation of a new a_0-like state at 1.817 GeV. We will also report the improved measurement of the strong-phase difference in quantum-correlated $D\bar{D}$ decays.
For charmed baryon, we will report the form factor measurement in $\Lambda_c^+ \to \Lambda e^+ \nu_e$, the observation of $\Lambda_c^+\to p K^- e^+ \nu_e$, and branching fraction measurements of $\Lambda_c$ singly-Cabibbo-suppressed decays.
Recent BESIII publication regarding Charmonium studies
Various nuclei, like Cu, Au, Pb, and U, have collided in various relativistic heavy-ion colliders to comprehend the medium of de-confined quarks and gluons called Quark-Gluon Plasma (QGP). The STAR data for isobar, Ru+Ru, and Zr+Zr, collisions at $\sqrt{s_{\mathrm {NN}}}$ = 200 GeV, provide hints of different nuclear structure between the two isobar nuclei through collective flow and multiplicity. All these colliding nuclei are observed to have different shapes and structures, which might also influence particle production. These collisions can be modeled using different configurations of Woods-Saxon (WS) distribution using the AMPT model and studying the influence of nuclear geometry on the particle production mechanisms.
In this talk, we will present transverse momentum spectra of pions, kaons, and (anti-)protons at mid-rapidity ($\lvert y \rvert$ $<$ 0.5) for Ru+Ru, Zr+Zr, Au+Au and U+U collisions at $\sqrt{s_{\mathrm {NN}}}$ = 200 GeV using a multi-phase transport (AMPT) model. The influence of various WS parametrizations on $p_{T}$-spectra, particle yield ($dN/dy$), mean transverse momentum ($\langle p_{T}\rangle$), and particle ratios will be discussed. The system size dependence of $dN/dy$ and $\langle p_{T}\rangle$ with different colliding systems will be presented. In addition, the physics implications of such studies in the context of nuclear structure in isobars will be highlighted.
n this talk I wish to clarify two questions that have been left unanswered in the paper D.Kharzeev and E. Levin:
``Deep inelastic scattering as a probe of entanglement,''
Phys. Rev. D \textbf{95} (2017) no.11, 114008.
In this paper we compute the von Neumann entropy of the system of partons resolved by deep inelastic scattering at a given Bjorken $x$ and momentum transfer $q^2 = - Q^2$. We interpret the result as the entropy of entanglement between the spatial region probed by deep inelastic scattering and the rest of the proton. Our calculation was done for the moment of time just after the wee parton from the parton cascade of a fast hadron interacts with the virtual photon ($t=0^+$). This interaction destroys the coherence of partons in a hadron and creates a system of partons with calculated entropy. However, we can measure the entropy as well as multiplicity distribution only in the final state: at $t=\infty$. In the talk I will discuss the entropy of produced particle both in the simple zero dimension model and in QCD. Recall, that $S_E = \ln xG(x,Q^2)$ we have computed in the zero dimension model. It tuns out that resulting entropy in both approaches is the same at $t=\infty$ as at $t=0^+$, in spite of a huge number of interactions that the partons have undertaken during the propagation from $t=0$ to $t=\infty$. The second observation is the non-perturbative correction can reduce the value of entropy.
In this talk we briefly overview various channels used for phenomenological studies of the partonic structure of the target, which is usually encoded in Generalized Parton Distributions (GPDs), and also summarize our recent theoretical studies of exclusive production of heavy mesons pairs (quarkonia and heavy-light $D$-mesons). We argue that at moderate energies (for example, in the kinematics of the future EIC), the production of quarkonia pairs might give important phenomenological restrictions for the gluon GPDs of the proton. Similarly, the production of the $D$-meson pairs is mostly sensitive to the GPDs of the light quarks of just one light quark flavour in ERBL region.
It was argued that local parity breaking may emerge in hot dense hadronic medium. We investigate the possibility of formation of photon and vector meson states localized in the transition region between domains with different axial chemical potential values. Using the vector meson dominance model modified to take into account parity-breaking backgrounds we obtain the spectrum of such states and study their evolution. We also investigate the impact of such boundaries on the exotic processes in the parity-breaking medium that were predicted in the preceding work.
Relativistic procedure of explicit accounting of the orbital momentum and
spin of the $V$-meson resonance
is suggested for the high energy inclusive reaction
$A+B\Longrightarrow V+X\Longrightarrow 1+2+X$.
It is compared decays of the structureless and composite $V$-mesons.
Composite mesons are constructed within to the general field-theoretical
approach,
where hadrons and hadron-resonances are bound states of quarks {\bf [1,2]}.
It is shown that structure of the meson generate
an
additional terms in the cross sections and in $V$-meson spin density matrix
and an additional dependence on the orbital momentum of this meson.
Special attention is given to the method of determining the $V$-meson spin quantization axis
and to the possibility of identifying the quark structure of $V$-meson resonance using experimental cross sections of reactions
$A+B\Longrightarrow V+X\Longrightarrow 1+2+X$.
{\bf [1]} K. Huang and H. A. Weldon. Bound state wave functions and bound state scattering in relativistic field theory. Phys. Rev. {\bf D11} (1975) 257
{\bf [2]} A. I. Machavariani and Amand Faessler. Current conservation and analytic determination of the magnetic moment of the $\Dela$ resonance in the
$\pi N$ bremsstrahlung: II. Formulation with quark degrees of freedom. III. Magnetic moment of the $\Delta^o$ and $\Delta^-$ resonances. J. Phys. G: Nucl. Part. Phys. {\bf 38} (2011) 035002
The simple picture of a hard scattering per $p$+$p$ collision has been challenged by several measurements performed at LHC and RHIC, revealing more complex dynamics of multiple parton interactions (MPI), which are essential to fully understanding particle production in hadronic collisions. Hard probe measurements at different particle multiplicity regimes in $p$+$p$ collisions provide a clean method to study (MPI). The PHENIX experiment has a unique capability to simultaneously measure particle production at forward ($1.2<\eta<2.2$), mid-($|\eta|<1$), and backward ($-2.2<\eta<-1.2$) rapidities. This presentation will report on the results of $J/\psi$ production in $p$+$p$ collisions at $\sqrt{s}=$ 200 GeV when the particle multiplicity is measured at different rapidity regions. The gap between the $J/\psi$ and the particle multiplicity measurement allows us to explore how the particles involved in the $J/\psi$ production itself can affect the multiplicity-dependent measurements.
When investigating the characteristics of the Quark-Gluon Plasma (QGP) formed in relativistic heavy ion collisions, it becomes imperative to categorize events based on the QGP's size and configuration. Conventionally, event categorization hinges on the dimensions and form of the QGP, achieved through the indirect mapping of the unobservable impact parameter onto a bulk observable, such as soft particle production. This mapping procedure inherently accommodates fluctuations arising from initial state nuclei and nucleon-nucleon interactions.
However, even within a stringent experimental centrality framework primarily reliant on multiplicity, the presence of diverse event shapes persists, courtesy of these inherent fluctuations. To attain more homogeneous event sub-samples, the inclusion of an additional, independent qualifier proves invaluable. A decade ago, event-shape engineering introduced the flow vector as a supplementary qualifier, albeit susceptible to final state interactions.
In our approach, we opt for an alternative method—utilizing spectator neutrons, precisely measured by the PHENIX zero-degree calorimeter, as the secondary dimension. This new approach offers a more precise method for categorizing QGP events, with significant implications for comprehending the underlying physics of heavy ion collisions.
Through the application of this novel 2D event characterization to Au+Au collisions at RHIC, we will demonstrate elliptic flow results with tighter constraints on the initial geometry. Additionally, we will discuss its relevance in studying phenomena like path-length dependent energy loss and potential multiple-parton interactions (MPI).
Forward and backward rapidity regions are rich laboratories to explore several effects which happens to a probe before and after its hard scattering. The large rapidity region may also test a different dynamics for strangeness enhancement seen in heavy ion collisions at RHIC and LHC. The PHENIX experiment has a long history of large rapidity measurements with the muon spectrometers covering 1.2<|𝜂|<2.2 and a forward calorimeter (MPC) covering 3.1<| 𝜂 |<3.8. The addition of a pre-shower detector, the MPC-ex in front of the MPC, allows the identification of $\pi^{0}$ in a broad momentum range covering a Bjorken-x region between 10$^{-3}$ − 10$^{−2}$. This talk will report two measurements: i) 𝜙 meson nuclear modification using the muon spectrometer in d + Au, Cu + Au and Au + Au which can explore how strangeness are affected by initial and final state effects and its behavior in QGP at large rapidity; ii) $\pi^{0}$ nuclear modification factor in d + Au collisions which are sensitive to parton shadowing and gluon saturation.
In the preparation period for precision measurements in the newly planned collider experiments, the understanding of the 3D structure of hadron is becoming increasingly urgent. This triggers the activities to include elements of Transverse Momentum Dependent (TMD) factorization physics in Monte Carlo event generators.
The method designed especially to address this need is the TMD Parton Branching (PB) method. In this talk, I present a brief overview of the PB method and its achievements and discuss the recent development to increase the low-qt resummation precision of the PB Sudakov form factor up to NNLL by using effective soft-gluon coupling. I illustrate its impact on parton densities and Drell-Yan prediction.
The Parton-Branching method (PB) is a powerful tool for determining Transverse Momentum Dependent (TMD) parton densities across a wide range of transverse momentum ($k_T$). It provides insights into both intrinsic parton motion and the contribution of soft gluons, particularly in the small $k_T$ range. Our research emphasizes the significance of soft gluons operating below a resolvable scale in shaping integrated and TMD parton densities.
To make predictions for Drell-Yan transverse momentum spectra across a diverse mass spectrum, we employ PB TMD parton densities in conjunction with NLO calculations following the MC@NLO style. By introducing a free parameter, we extract the intrinsic $k_T$ width by comparing experimental data with predictions based on the PB-NLO-HERAI+II-2018 set2 TMD framework. Notably, unlike alternative methods, our approach reveals that the intrinsic $k_T$ distribution width remains unaffected by the mass of the Drell-Yan pair and the center-of-mass energy ($\sqrt s$).
The standard Model describes well the ordinary matter, but it fails to accommodate recent experimental anomalies, such as dark matter. Dark matter is inferred by the gravitational effect only, and its nature is a mystery. Dark matter may couple to the ordinary matter via portals. The corresponding particles could be light Higgs and dark bosons, axion-like particles and spin-1/2 fermion. These particles can be accessible by high-intensity electron-positron collider experiments, such as the BESIII experiment, if the masses of these particles are up to the level of a few GeV. BESIII has recently explored the possibility of light Higgs boson, dark photon, axion-like particles and various flavors of light dark matter particles using the data samples collected in the tau-charm region. This report will summarize the recent results of the BESIII related to dark matter searches.
The BABAR experiment continues to produce interesting new constraints from searches for new physics in exotic and dark sector signatures using its extensive data set of B factory data collected in the vicinity of the Upsilon(4S) resonance. This large data set, with well-understood detector conditions and precisely controlled systematics, has demonstrated utility for both exotic rare decay searches and high-statistics precision measurements of Standard Model observables with potential sensitivity to new physics contributions. This presentation will summarize recent BABAR results of searches for light dark matter candidates in B meson decays, heavy neutral leptons, and charged lepton flavour violation. The implications for g-2 of recent precision measurements of the e+e- hadronic cross sections will also be discussed.
The Micromegas detectors are part of the New Small Wheel (NSW) system of the ATLAS experiment, the largest upgrade project of Phase-1. Together with sTGC detectors they provide trigger and tracking capability in the innermost station of the end-cap part of the Muon
spectrometer.
The Micromegas detector of ATLAS cover an active area of about 1280 m^2, has 1024 HV channels and 2.1 M readout channels, representing
the largest Micro-Pattern Gaseous Detector system ever built.
The two NSW have been installed in ATLAS in time for the start of Run3, went through a detailed commissioning phase during 2022 and are now
contributing to the ATLAS data taking.
In this presentation, after an introduction of the NSW, a series of latest
results regarding simulations, reconstruction, performance and first data
obtained with Run 3 will be reported.
The instantaneous luminosity of the Large Hadron
Collider at CERN will be increased by about a factor
of five with respect to the design value by
undergoing an extensive upgrade program over the
coming decade. The largest phase-1 upgrade project
for the ATLAS Muon System was the replacement of the
first station in the forward regions with the New
Small Wheels (NSWs) which took place during the long-
LHC shutdown in 2019-2021.
The two Small Wheels are called A and C and cover a
positive and negative pseudorapidity acceptance in
the range |η| =1.3 to 2.7. Both Small Wheels have
been successfully installed in ATLAS in 2021 and took
data from p+p collisions at 13.6 TeV in 2022.
Along with resistive strips Micromegas, the NSW's is
equipped with eight layers of small-strip thin gap
chambers (sTGC). The new system is designed to assure
high tracking efficiency, reduction of fake trigger
rates and precision measurement of muon tracks. In
this presentation we will discuss the performances of
the sTGC detectors from data taken with the first LHC
beam in 2022 and 2023.
The instantaneous luminosity of the Large Hadron
Collider at CERN will be increased by about a factor
of five with respect to the design value by
undergoing an extensive upgrade program over the
coming decade. The largest phase-1 upgrade project
for the ATLAS Muon System was the replacement of the
first station in the forward regions with the New
Small Wheels (NSWs) which took place during the long-
LHC shutdown in 2019-2021.
The two Small Wheels cover a positive and negative
pseudorapidity acceptance in the range |η| =1.3 to
2.7. Both Small Wheels have been successfully
installed in ATLAS in 2021 and took data from p+p
collisions at 13.6 TeV in 2022.
Along with resistive strips Micromegas, the NSW's is
equipped with eight layers of small-strip thin gap
chambers (sTGC). The new system is designed to assure
high tracking efficiency, reduction of fake trigger
rates and precision measurement of muon tracks. In
this presentation we will show results on the rates
of the sTGC detectors from data taken with the first
LHC beam in 2022.
The Jiangmen Underground Neutrino Observatory (JUNO) is located in Jiangmen, Guangdong, China, with an overburden of about 700 meters. The baseline for measuring the reactor antineutrinos of two nuclear power plants is 53 km. The central detector composes of 20 kton liquid scintillator, a 35.4 m diameter acrylics sphere, a 40.1 m diameter stainless steel latticed shell, and an independent double calorimetry system. This system consists of 17,612 20-inch large PMTs (LPMTs) and 25,600 3-inch small photomultiplier tubes (SPMTs), providing a total photo-coverage of 78%.
The primary goal of JUNO experiment is to determine the neutrino mass hierarchy by measuring the fine structure of the oscillation spectrum with a significance of 3~4 σ in 6 years of data taking. Additionally, the experiment aims to precisely measure the mixing parameters, θ_12 , ∆m_12 and ∆m_ee^2.
To achieve this, a high energy resolution of 3% at 1 MeV is required, which necessitates high optical coverage, large area PMT with high quantum efficiency, high transparency liquid scintillator (LS), and low backgrounds.
In addition to these goals, the experiment will also look for geo-neutrinos, solar-neutrinos, atmospheric neutrinos, supernova neutrinos and neutrinos from dark matter annihilations. This talk will present the physics prospects, detectors, and the current status of JUNO.
I will describe the status and the R&D efforts towards the next generation of gravitational wave detectors with a focus on the frequency range accesible by detectors on earth, namely the Cosmic Explorer and the Einstein Telescope.
High-energy collisions allow us to study the behaviour of matter at high temperature and density. Various experimental signatures suggest that a new state of matter called Quark-Gluon Plasma (QGP) is produced in heavy-ion collisions. However, recent results suggest that high-multiplicity $p$+$p$ collisions might also be able to produce QGP droplets. Therefore, there is a pressing need to gain deeper insights into $p$+$p$ collisions to understand the properties of the produced system. Tsallis statistics is a non-extensive statistical mechanics framework that has been used to successfully describe a wide range of complex systems, including high-energy collisions. We use thermodynamically consistent Tsallis statistics to study the charged hadron spectra from $p$+$p$, $p$+Pb, Xe+Xe, and Pb+Pb collisions at the LHC.
In this talk, we will show the system size dependence of various thermodynamic variables at the kinetic freeze-out (KFO) surface. Our results show that the rate of increase (or decrease) with system size of various thermodynamic variables is more rapid in small systems such as $p$+$p$ and $p$+Pb collisions than in large systems such as Xe+Xe and Pb+Pb collisions. Moreover, we also find that the magnitudes of different thermodynamic variables in high-multiplicity $p$+$p$ collisions are comparable to those in peripheral heavy-ion collisions.
High-energy heavy-ion collision experiments aim to explore the phase transition from normal hadronic matter to the quark-gluon plasma (QGP), a deconfined state of quarks and gluons. The dynamics of relativistic heavy-ion collisions at various collision energies have been extensively studied using A Multi-Phase Transport (AMPT) model. The AMPT model is very sensitive to the input parameters, therefore, the choice of these parameters are very important to explain the results from various experiments. This study aims to find the most suitable input parameters to understand particle production mechanism and bulk properties of the medium formed at different Beam Energy Scan (BES) energies at RHIC.
In this talk, we will present the transverse momentum spectra of identified hadrons in Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7-200 GeV obtained from AMPT model and compare it with the available experimental results. We will also present the energy dependence of particle yields (dN/dy), average transverse momentum ($\langle p_{T} \rangle$), particle ratios, and compare them with experimental data.
We present a novel method of extraction of the Collins-Soper kernel directly from the comparison of differential cross-sections measured at different energies. Using this method, we provide feasibility studies for the direct measurement of the Collins-Soper kernel with the CMS detector. We also solve a long standing problem of comparison between TMDs obtained from PB and factorization approaches.
Latest heavy ion results from PHENIX at RHIC (invited)
Recent results from the STAR experiment at RHIC
sPHENIX is a new collider detector at RHIC designed for pioneering studies of the Quark-Gluon Plasma with jets and heavy flavor probes. The large acceptance of the detector, including forward sub-detectors; as well as excellent tracking and high data-taking rate also allows for the measurement of bulk phenomena such as soft particle production and collective flow. Commissioning of sPHENIX with Au+Au collisions at 200 GeV began in May 2023. This talk will give a technical report of the status of sPHENIX sub-systems relevant for bulk physics; as well as a report on the first bulk physics measurements since commissioning.
Photons provide snapshots of the evolution of relativistic heavy-ion collisions as they are emitted at all stages and do not interact with the medium strongly. Measurements of low momentum direct photons at PHENIX across different systems, from p+p to Au+Au have been made possible due to the versatility of RHIC. An excess of direct photons above prompt photon production from hard scattering processes and consistent with thermal photon emission is observed in collisions of large systems. State-of-the-art theoretical models describe the data qualitatively, however, they fall short quantitatively. Precise measurement of the direct photon anisotropy is necessary to constrain these theoretical models and to provide insights into the space-time evolution of relativistic heavy-ion collisions. In this talk, azimuthal anisotropies of direct photons in Au+Au collisions at 200 GeV will be presented, thereby, shedding light on the long-standing direct photon puzzle.
The SPD experiment will be built at the NICA collider in JINR, which will accelerate polarized pp (dd) beams with collision energy up to 27 GeV (13.5 GeV) per nucleon. The primary goal of SPD is the study of the spin-dependent gluon structure of proton and deuteron by providing access to gluon TMD functions. At the same time, the physics program of the experiment extends to the investigation of a variety of other polarized and unpolarized QCD phenomena. The talk will give an overview of the physics program, experimental set-up, expected performance, and project status.
The Jiangmen Underground Neutrino Observatory (JUNO) is an experiment being built in China, which consists of a 20 kt liquid scintillator detector. The main objective of the experiment is to determine the neutrino mass ordering by measuring reactor anti-neutrinos at 53 km baseline. The experiment is also expected to have a high sensitivity to geoneutrinos, electron antineutrinos from natural radioactivity decay chains of 238-Uranium and 232-Thorium in the Earth. The radiogenic heat released in these decays is in a well established relationship with the abundances of Uranium and Thorium. Thus, the measurement of geoneutrino flux can provide an insight on the Earth's energy budget. Even more, distinguishing the signal coming from the Earth's mantle is a key feature which can unveil its convection scheme and contribution to the total radiogenic heat. Within the first year of data taking, JUNO will be able to exceed the total statistics of both Borexino and KamLAND experiments. With increased statistics, JUNO will be able to measure Uranium and Thorium fluxes individually and to establish their ratio, yet another important parameter for the geo-science community, giving insights about the Earth's formation process.
The talk will focus on the geoneutrino's sensitivity study at the JUNO experiment, reporting the expected precision of measuring the total and independent contributions of geoneutrinos from U and Th.
The constituents of dark matter are still unknown, and the viable possibilities span a very large mass range. Specific scenarios for the origin of dark matter sharpen the focus on a narrower range of masses: the natural scenario where dark matter originates from thermal contact with familiar matter in the early Universe requires the DM mass to lie within about an MeV to 100 TeV. Considerable experimental attention has been given to exploring Weakly Interacting Massive Particles in the upper end of this range (few GeV – ~TeV), while the region ~MeV to ~GeV is largely unexplored. Most of the stable constituents of known matter have masses in this lower range, tantalizing hints for physics beyond the Standard Model have been found here, and a thermal origin for dark matter works in a simple and predictive manner in this mass range as well. It is therefore a priority to explore. If there is an interaction between light DM and ordinary matter, as there must be in the case of a thermal origin, then there necessarily is a production mechanism in accelerator-based experiments. The most sensitive way, (if the interaction is not electron-phobic) to search for this production is to use a primary electron beam to produce DM in fixed-target collisions. The Light Dark Matter eXperiment (LDMX) is a planned electron-beam fixed-target missing-momentum experiment that has unique sensitivity to light DM in the sub-GeV range. This contribution will give an overview of the theoretical motivation, the main experimental challenges and how they are addressed, as well as projected sensitivities in comparison to other experiments.
The MATHUSLA experiment is a proposed large-volume detector for long lived particles (LLPs) produced at the CERN HL-LHC. The detector would be sited on the surface adjacent to the CMS interaction region, shielded from the LHC by approximately 100m of rock. Non-interacting LLPs which penetrate this rock and decay within the MATHUSLA instrumented volume would be reconstructed via their decays into standard model charged particles. Sensitivity in the benchmark model of $H \to \chi \bar{\chi}$ is expected to be $\sim3$ orders of magnitude better than the main LHC experiments. Arrays of plastic scintillator bars will provide tracking information for LLP decay vertex reconstruction, directionality, and vetoing of backgrounds both from cosmic rays and LHC sources. This presentation will discuss the physics motivation, detector concept and the expected physics sensitivity, as well as describe ongoing detector research and development activities related to the Conceptual Design Report for the MATHUSLA experiment.
We fit the transverse momentum spectra of hadrons from intermediate heavy-ion collisions, generated by two microscopic transport models, UrQMD and SMASH, to Boltzmann-Gibbs and to Tsallis distributions. The analysis is done (i) for the evolution of hot and dense nuclear matter in central area of central heavy-ion collisions and (ii) for the infinite nuclear matter, simulated in both models via a box with periodic boundary conditions. The obtained results favour the application of the Tsallis statistics in comparison with the Boltzmann-Gibbs one.
We study a bino-like light neutralino ($\tilde \chi_1^0$) produced at the LHC from the decay of a scalar lepton ($\tilde e_L$) through the process $pp\to \tilde e_{L} \to e\tilde \chi_1^0$ in the context of R-parity-violating (RPV) supersymmetry where $\tilde \chi_1^0$ is the lightest supersymmetric particle. For small masses and RPV couplings, the neutralino is naturally long-lived and its decay products can be identified as displaced tracks. Following existing searches, we propose a displaced-vertex search strategy for such a light neutralino with a single RPV coupling switched on, $\lambda'_{111}$, in the mass range $10\,\mbox{GeV} \lesssim m_{\tilde \chi_1^0}\lesssim 230\,\mbox{GeV}$. We perform Monte Carlo simulations and conclude that at the high-luminosity LHC, the proposed search can probe values of $\lambda'_{111}$ down to two orders of magnitude smaller than current bounds and up to 40 times smaller than projected limits from monolepton searches.
Probing the Quark-Gluon Plasma with the sPHENIX Detector at RHIC
In this talk I will present the homotopy method for solving the non-linear evolution Balitsky-Kovchegov equation.
In this approach we need first the analytical solution for the linearized version of the non-linear BK evolution equation deep in the saturation region. Then, the perturbative procedure is suggested to take into account the remaining parts of the non-linear corrections. This result can be used for differents studies in hight energy process.
Recent spin physics results from PHENIX
With large acceptance and excellent particle identification, STAR has facilitated a variety of exciting measurements covering a wide range of physics topics.
The versatility and precision of the STAR detector, accompanied by the unique capability of RHIC to collide polarized hadrons at various energies, has opened new avenues for investigations of the proton spin structure.
Calorimetry at STAR allows reconstruction of $W^{\pm}/Z$ bosons by tagging their decay electron.
Measurements of the reconstructed $W^{\pm}$ in longitudinally polarized collisions probe asymmetric anti-quark helicity distributions in the proton sea.
In transversely polarized collisions, the $W^{\pm}/Z$ bosons probe the sea-quark Sivers function and contribute to tests of the predicted sign change.
Jets can be reconstructed based on additional information provided by the STAR tracking system.
The longitudinal double-spin asymmetry, $A_{LL}$, in inclusive jet and dijet production at STAR provides the first evidence of a positive gluon polarization with partonic momentum fraction $x > 0.05$.
The tilt of the dijet opening angle in transversely polarized collisions provides a direct access to the first Mellin momentum of the Sivers function.% and avoids the spin-correlated fragmentation contributions.
With the excellent particle identification at STAR, one can pick out hadrons within a jet.
$A_{LL}$ of jets that are tagged with a $\pi^{\pm}$ provides additional examinations of the sign of gluon helicity.
Novel measurements of azimuthal distributions of identified hadrons in jets in transversely polarized collisions directly probe the collinear quark transversity via coupling to transverse momentum dependent (TMD) Collins fragmentation function.
The identified hadrons, without being tagged to a jet, provide additional probes of the proton spin structure.
Azimuthal correlation between hadron pairs and the proton spin direction provides a complementary extraction of transversity via coupling to dihadron interference fragmentation function.
Longitudinal and transverse spin transfers to $\Lambda(\bar{\Lambda})$ hyperons allow access to much unknown $s(\bar{s})$ helicity and transversity, respectively.
In this talk, an overview of spin physics at STAR will be presented.
Direct neutrino mass measurements
Over the past half-decade, the realm of solar neutrino physics has been illuminated with groundbreaking discoveries. These encompass the meticulous 3% measurements of $^7$Be solar neutrinos, the pioneering detection of CNO solar neutrinos, and the debut measurements of solar core C+N relative abundances utilizing solar neutrinos.
The upcoming contributions from experiments like JUNO, Hyper-K, and DUNE are poised to further enhance our understanding of solar neutrino physics. Borexino has astoundingly showcased the capability to extract directional information from conventional liquid scintillator detectors. In parallel, next-generation directional experiments such as Theia and the Jinping Neutrino Experiment are expected to push the boundaries of CNO solar neutrino measurements.
As we stand at this juncture, solar neutrinos are no longer just cosmic messengers but are evolving into precision tools. They open the portals to a deeper grasp of solar physics, matter effects, and potential new physics vistas.
In this talk, I will embark on a journey through these recent experimental breakthroughs, their future potential, and the consequent profound implications for solar neutrino physics.
Coherent elastic neutrino-nucleus scattering
Searching for New Physics at the LHC using Effective Field Theory
Experiments at the Large Hadron Collider (LHC) search for new physics beyond the standard model that could explain some of the shortcomings of the standard model. A selection of results for searches for new physics beyond the standard model using data recorded by the ATLAS, CMS and LHCb experiments are presented. The results are based on proton-proton collision data collected during Run 2 of the LHC.
Recent experimental results on heavy-ion collisions at RHIC and LHC
The anomalous excess of soft photons radiated in inelastic hadronic collisions, has been a challenge over four decades. The problem is rooted in comparison with an incorrect model for radiative corrections, which is based on an illegitimate extension of the Low theorem to radiative multi-particle production processes $2\to n+\gamma$. It turns out to contradict the unitarity relation and the optical theorem. The alternative description of photon radiation within the light-front color-dipole phenomenology is found to be in a good accord with data.
Electroweak measurements from high statistics LHC data
Searches for signatures with heavy stable neutral particles at the LHC
PIC 2024