Conveners
Heavy Ions: Heavy Ions
- Emilie Maurice (Ecole polytechnique - Centre National de la Recherche Scientifique (FR))
Heavy Ions: Heavy Ions
- Katarina Krizkova Gajdosova (Czech Technical University in Prague (CZ))
Heavy Ions: Heavy Ions
- Katarina Krizkova Gajdosova (Czech Technical University in Prague (CZ))
Heavy Ions: Heavy Ions
- Liliana Apolinario (LIP (PT))
Heavy Ions: Heavy Ions
- Emilie Maurice (Ecole polytechnique - Centre National de la Recherche Scientifique (FR))
Heavy Ions: Heavy Ions
- Liliana Apolinario (LIP (PT))
Heavy Ions: Heavy Ions
- Liliana Apolinario (LIP (PT))
Heavy Ions: Heavy Ions
- Emilie Maurice (Ecole polytechnique - Centre National de la Recherche Scientifique (FR))
Heavy Ions: Heavy Ions
- Liliana Apolinario (LIP (PT))
Heavy Ions: Heavy Ions
- Iurii Karpenko (FNSPE CTU in Prague)
Heavy ion collisions allow access to novel QCD and QED studies in a laboratory setting. This talk will present recent CMS highlights on precision measurements of the properties of quark-gluon plasma and the strong electromagnetic fields produced in high-energy heavy ion collisions.
The research conducted by the NA61/SHINE spans a broad spectrum of hadronic physics within the CERN SPS energy range.This presentation will delve into the energy-dependent characteristics derived from the SMES model (the horn and step phenomena), along with the latest findings concerning particle production properties observed in p+p collisions and Be+Be, Ar+Sc, and Xe+La collisions at SPS...
The LHCb detector is a unique tool for studying high-energy heavy-ion colli-
sions. Its forward geometry, along with its excellent vertex reconstruction and
particle identification capabilities, allow the LHCb detector to study a wide vari-
ety of observables in pPb and PbPb collisions in previously unexplored kinematic
territory. Recent results from the LHCb heavy-ion program will be...
Owing to the injection of gas into the LHC beampipe while multi-TeV proton
or ion beams are circulating, the LHCb spectrometer has the unique capabil-
ity to function as the as-of-today highest-energy fixed-target experiment. The
resulting beam-gas collisions cover an unexplored energy range that is above
previous fixed-target experiments, but below RHIC or LHC collider energies.
In this...
sPHENIX is a next-generation, state-of-the-art particle detector at the Relativistic Heavy-Ion Collider (RHIC) that has recently taken its first dataset of 200 GeV Au+Au collisions during a commissioning run in 2023. sPHENIX features a variety of subsystem capable of detailed studies of bulk particle production in heavy-ion collisions, including the first barrel hadronic calorimeter at RHIC....
The pseudorapidity dependence of charged particle production provides information on the partonic structure of the colliding hadrons and is, in particular at LHC energies, sensitive to non-linear QCD evolution in the initial state. For Run3, ALICE has increased its pseudorapidity coverage to track charged particles over a wider range of โ3.6 < $\eta$ < 2 combining the measurement from the...
This talk presents a comprehensive overview of recent ATLAS measurements of collective flow phenomena in a variety of collision systems. Measurements of the mean, variance, and skewness of the distribution of event-by-event per- particle average transverse momentum, [pT] are reported for Pb+Pb collisions at 5.02 TeV and Xe+Xe collisions at 5.44 TeV. These measurements give insight into the...
We investigate the possibility of a partonic phase in small systems with the elliptic flow of mesons (ฯโบโป, Kโบโป, Kโฐ) and baryons (p+pฬ , ฮ+ฮฬ ) in high-multiplicity p--Pb collisions at $\sqrt{s_{{\rm NN}}}$ = 5.02 TeV and pp collisions at $\sqrt{s}$ = 13 TeV measured by ALICE. The results show a grouping (with 1$\sigma$ significance) and splitting (with 5$\sigma$ confidence) behavior of $v_2$ at...
Studies have yielded strong evidence that a deconfined state of quarks and gluons, the quark-gluon plasma, is created in heavy-ion collisions. This hot and dense matter exhibits almost zero friction and a strong collective behavior. An unexpected collective behavior has also been observed in small collision systems. In this talk, the origin of collectivity in small collision systems, which is...
Precision measurements of transverse momentum-differential elliptic flow, $v_{2}(p_{\rm T})$, of identified particles have been done in proton-lead (p-Pb) collisions. The characteristic mass-ordering of $v_{2}(p_{\rm T})$ at low $p_{\rm T}$ and the grouping/splitting of $v_{2}(p_{\rm T})$ for mesons and baryons at intermediate $p_{\rm T}$, which have been regarded as the smoking gun of QGP...
Balance functions have been used extensively to elucidate the time evolution of quark production in heavy-ion collisions. Early models predicted two stages of quark production, one for light quarks and one for the heavier strange quark, separated by a period of isentropic expansion. This led to the notion of clocking particle production and tracking radial flow effects, which drive the...
Measurements of light-flavour particle production in small collision systems at the LHC energies have shown the onset of features that resemble what is typically observed in nucleus- nucleus collisions. New results on the (multi-)strange hadron production in PbโPb collisions at $\sqrt{s_{\rm NN}}$ =5.02 and 5.36 TeV will be presented. These results are discussed in the context of recent...
For the first time, correlations between higher order moments of two and three Fourier flow harmonics (up to orders 8 or 10) are measured in Run 2 XeXe (deformed nuclei) and Run 3 PbPb (spherical nuclei) collisions data as a function of collision centrality. The measurements are performed with multiparticle mixed harmonic cumulants using charged particles in the pseudorapidity region...
The speed of sound squared, $c_s^2$, a property of the quark-gluon plasma (QGP) connected to the QCD equation of state, can be extracted from ultra-central heavy-ion collisions, where the medium maintains a fixed size and the initial-state and thermal fluctuations dominate. We present the first ALICE measurements of the event-by-event mean transverse momentum, $\langle[p_\mathrm{T}]\rangle$,...
The elliptic flow ($v_2$) of identified hadrons is an observable sensitive to the early dynamics of heavy-ion collisions and to the equation of state (EoS) of the medium. In particular, strange and (multi-) strange baryons have small hadronic cross-sections, thus being clean probes of the early stages of the collision systems' evolution. Additionally, strange and multi-strange baryons are also...
Intense electromagnetic fields from ultrarelativistic heavy ions can trigger photonuclear reactions, which can be used to probe the nuclear gluon distribution at low Bjorken-$x$ and targets gluonic fluctuations. Our study examines ultra-peripheral and nuclear-overlap collisions, covering measurements of peripheral Pb--Pb collisions' $y$-differential cross section and coherent J/$\psi$...
We discuss exclusive heavy-vector-meson photoproduction in ultraperipheral collisions at the LHC in a tamed collinear factorisation approach at Next-to-Leading Order (NLO). By employing the Shuvaev transform as a reliable means to relate Generalised Parton Distributions (GPDs) to Parton Distribution Functions (PDFs) at small values of the skewness parameter ฮพ, we perform a parton analysis...
Relativistic heavy-ion beams at the LHC are accompanied by a large flux of nearly-real photons, leading to a variety of photon-induced processes. This talk presents a series of measurements of dilepton production from photon fu- sion performed by the ATLAS Collaboration. Recent measurements of exclu- sive dielectron production in ultra-peripheral collisions (UPCs) are presented. These...
We will present the latest measurements of charmonia photoproduction and two-photon processes in ultra-peripheral Pb-Pb collisions at the LHC, using the ALICE detector. These processes probe the nuclear gluon distribution at low Bjorken-x and QED effects in strong fields. ALICE has an active program on UPC physics, which is benefiting from the Run 3 detector upgrades because of a continuous...
We will present the latest measurements of the anomalous magnetic moment (g โ 2) of the tau lepton at CMS. These are obtained from photon-induced processes in heavy-ion collisions, or in proton-proton collisions.
In ultraperipheral Pb+Pb collisions, intense electromagnetic fields enable the generation of magnetic monopole pairs via the Schwinger mechanism. Due to their high ionization and unique trajectories in a solenoidal magnetic field, monopoles are expected to leave a large number of clusters in the innermost ATLAS pixel detector without associated reconstructed charged-particle tracks or...
Heavy quarks, i.e. charm and beauty, are produced at the initial stage of heavy-ion collisions. In the presence of a large angular momentum and initial magnetic field, they can be polarised. The quark polarisation is expected to be transferred to the hadron during the hadronisation process, and it can be probed by measuring the $\rho_{00}$ parameter of the spin density matrix element of spin-1...
The Zubarev approach of the non-equilibrium statistical operator [1] is used to account for the enhancement of the low-$p_T$ part of pion spectra by introducing an effective pion chemical potential [2]. This is an alternative to the explanation of the low-$p_T$ enhancement by resonance decays. We report on the first results obtained with a newly developed thermal particle generator that...
Well established measurements of high-multiplicity proton-proton (pp) and proton-lead (p-Pb) collisions at the LHC have revealed that small collision systems show the onset of phenomena (e.g. strangeness enhancement, collective flow) typical of heavy-ion collisions, suggesting that light-flavor hadron production arises from a set of complex mechanisms whose relative contributions evolve...
Strangeness production in heavy-ion collisions is a longstanding and actively researched topic, offering crucial insights into the properties of strongly interacting matter. The NA61/SHINE experiment at CERN SPS North Area is one of the leading experiments in this field, focusing on measuring hadron production in a wide range of collision energies and system sizes.
This talk emphasizes the...
We use the Boltzmann Equation in Diffusion Approximation (BEDA) as a tool to explore the time evolution of an initially out-of-equilibrium and highly occupied expanding system of gluons. We study the hydrodynamization of this system as well as the quark production until chemical equilibration is established. A comprehensive study of such processes will be presented based on parametrical...
In this talk, we present our recent studies on thermal field theories using quantum algorithms. We first delve into the presentations of quantum fields via qubits on general digital quantum computers alongside the quantum algorithms employed to evaluate thermal properties of generic quantum field theories. Then, we show our numerical results of thermal field theories in 1+1 dimensions using...
We study whether in-medium showers of high-energy quarks and gluons can be treated as a sequence of individual splitting processes or whether there is significant quantum overlap between where one splitting ends and the next begins. Accounting for the Landau-Pomeranchuk-Migdal (LPM) effect, we calculate such overlap effects to leading order in high-energy $ฮฑ_s(\mu)$ for the simplest...
Resonance production is one of the key observables to study the dynamics of high-energy collisions. The analysis of $K^*(892)^0$ meson allows to better understand the time evolution of high-energy nucleus-nucleus collision. Namely, the ratio of $K^*(892)^0$ to charged kaons is used to determine the time between chemical and kinetic freeze-outs.
In this talk, the first NA61/SHINE results of...
The correlations between net-conserved quantities such as net-baryon, net-charge and net-strangeness play a crucial role in the study of QCD phase structure, as they are closely related to the ratios of thermodynamic susceptibilities in lattice QCD (LQCD) calculations. This presentation introduces new results focusing on the correlations between net-kaon and net-proton as well as net-kaon and...
The FASTSUM Collaboration has developed a comprehensive research programme in thermal lattice QCD using 2+1 flavour ensembles. We will review our recent hadron spectrum results including analyses of open charm mesons and charm baryons at non-zero temperature. We also detail our determination of the interquark potential in the bottomonium system using NRQCD quarks. Finally, we summarise our...
Direct photons are emitted throughout the development of a relativistic heavy ion collisions; their observation, therefore, provides a snapshot of the evolution of the collisions.This talk will present the latest results of the PHENIX experiment at RHIC obtained from high statistics Au+Au data set taken at 200 GeV. The results expand earlier measurements and isolate the non-prompt direct...
Electromagnetic probes are a unique tool to study the space-time evolution of the hot and dense matter created in ultra-relativistic heavy-ion collisions. More specifically, dielectron pairs are emitted as thermal radiation during all stages of the collision, allowing the extraction of the real direct photon fraction at vanishing mass. Measurements in pp collisions both serve as a baseline for...
Measurements of jets in heavy-ion collisions provide detailed information about the dynamics of the hot, dense plasma formed in these colli- sions at the LHC. This talk gives an overview of the latest jet measurements with the ATLAS detector at the LHC, utilizing the high statistics 5.02 TeV Pb+Pb and 8.16 TeV p+Pb data collected in 2015, 2016 and 2018. Multiple new results will be featured in...
The measurement of jets recoiling from a trigger hadron provides unique probes of medium-induced modification of jet production. Jet deflection via multiple soft scatterings with the medium constituents may broaden the azimuthal correlation between the trigger hadron and the recoiling jets. The R-dependence of recoil jet yield probes jet energy loss and intra-jet broadening. The hadron+jet...
We use the parametric approach to analyze jet suppression measured using the nuclear modification factor of inclusive jets and jets from gamma-jet events. With minimum model assumptions, we quantify the magnitude of the average energy loss, its pt-dependence, and flavor dependence. Further, we quantify the impact of fluctuations in the energy loss and nuclear PDFs on the measured jet...
Based on a data-driven approach and a scaling analysis, we demonstrate that the quenching of hadron spectra at RHIC and LHC allows for a precise determination of the path-length dependence of parton energy loss in quark-gluon plasma. We find that the average energy loss is proportional $\langle \epsilon \rangle \propto L^\beta$ with $\beta=1.02^{+0.09}_{-0.06}$, consistent with the pQCD...
In this talk we discuss factorization of jet cross sections in heavy-ion collisions based on fixed-order calculations. First, using Glauber modelling of heavy nuclei, a factorized formula for jet cross sections is derived, which involves defining jet functions in QCD medium. Then, we present our result of the jet function for producing a heavy quark-antiquark pair, denoted by $Q\bar{Q}$, at...
Two-dimensional (2D) jet tomography is a promising tool to study jet medium modification in high-energy heavy-ion collisions. It combines gradient (transverse) and longitudinal jet tomography for selection of events with localized initial jet production positions. It exploits the transverse asymmetry and energy loss that depend, respectively, on the transverse gradient and jet path length...
Quarkonium production in ultrarelativistic heavy ions collisions is one of the best probes of the QGP formed in these collisions. Resorting to acurate methods to describe the $Q\bar Q$ evolution in a QGP is a prerequisite for the precise interpretation of experimental data. Following [1], we present exact numerical solutions in a 1D setting of quantum master equations (QME) derived in [2]....
Quarkonium is an ideal probe to explore the properties of QCD. Unlike Large Hadron Collider (LHC) measurements, quarkonium production at the Relativistic Heavy Ion Collider (RHIC) has different production mechanisms, can access different kinematic phase space and may experience different medium densities/temperatures. The PHENIX experiment has collected a large $J/\psi \to \mu^{+}\mu^{-}$ data...
Measurements of top quarks in heavy-ion collisions are expected to provide novel probes of nuclear modifications to parton distribution functions as well as to bring unique information about the evolution of strongly interacting mat- ter. We report the observation of the top-quark pair production in proton-lead collisions at the centre-of-mass energy of 8.16 TeV in the ATLAS experiment at the...
Charmonia is a valuable tool to investigate nuclear matter under extreme conditions, particularly in the strongly interacting medium formed during heavy-ion collisions. At the LHC energies, the regeneration process has been found to significantly impact the observed charmonium characteristics. In particular, the ฯ(2S) production relative to J/ฯ is a physical observable with strong...
Open heavy flavor and quarkonium have long been identified as ideal probes for understanding the quark-gluon plasma (QGP). Heavy quarks are produced in the early stage of the heavy-ion collisions, therefore they experience the evolution of the medium produced, providing an important tool to investigate the properties of the QGP. In particular, the magnitude of the elliptic flow measured at the...
Using an event-by-event Boltzmann transport approach with an hadronization via coalescence plus fragmentation, we investigate charm dynamics and the extension to bottom (b) quark dynamics providing predictions for RAA and v2,3 of B mesons comparing to the data by ALICE collaboration. A sizeable v2,3 is found with important implications on bottomonium ฮฅ production. The extension to b quark...
Heavy baryon production in various collision systems, from RHIC to LHC energies, is a challenge for theoretical understanding of heavy quarks (HQs) hadronization. An hadronization via coalescence-fragmentation predicts large ฮc/D0 from AA collisions at RHIC and LHC to pp collisions at top LHC energies. The model shows significant enhancements in ฮc/D0 and โฆc/D0 in pp collisions in agreement...
Heavy quarks (charm and beauty) serve as useful probes for investigating the properties of the quark-gluon plasma (QGP) generated in ultrarelativistic heavy-ion collisions. The characterisation of the heavy-quark in-medium energy loss and of their diffusion process within the medium are, in particular, of great interest.
In this contribution, measurements of charm-hadron $R_{\rm{AA}}$ and...
In this work we present the first semi-analytical predictions of the azimuthal anisotropies for jets in heavy-ion collisions, obtaining a quantitative agreement with available experimental data. Jets are multi-partonic, extended objects and their energy loss is sensitive to substructure fluctuations. We find that jet azimuthal anisotropies have a specially strong dependence on color coherence...
We investigate possible signatures of gluon saturation using forward p + A โ j + j + X di-jet production processes at the Large Hadron Collider. In the forward rapidity region, this is a highly asymmetric process where partons with large longitudinal momentum fraction x in the dilute projectile are used as a probe to resolve the small x partonic content of the dense target. Such dilute-dense...
We present a new coherent jet energy loss model for heavy-ion collisions. It is implemented as a Monte Carlo perturbative final-state parton shower followed by elastic and radiative collisions with the medium constituents. Coherency is achieved by starting with trial gluons that act as field dressing of the initial jet parton. These are formed according to a Gunion-Bertsch seed. The QCD...
In recent years, research studies in high-energy physics have confirmed the creation of strongly interacting quark-gluon plasma (sQGP) in ultra-relativistic nucleus-nucleus collisions. NA61/SHINE at CERN SPS investigates hadronic matter properties by varying collision energy (ranging from 5 GeV to 17 GeV) and systems (such as p+p, p+Pb, Be+Be, Ar+Sc, Xe+La, Pb+Pb). Utilizing femtoscopic...
Femtoscopy is a unique tool to investigate the space-time geometry of the matter created in ultra-relativistic collisions. If the probability density distribution of hadron emission is parametrized, then the dependence of its parameters on particle momentum, collision energy, and collision geometry can be given. In recent years, several measurements have come to light that indicate the...
Spaceโtime properties of quark--gluon plasma (QGP), a state of matter with unbound partons produced in heavy-ion collisions, can be studied using femtoscopic correlations of particle pairs emitted after the hadronization.
In this talk, results of 1D and 3D femtoscopic analyses of identical charged kaon pairs are reported in p--Pb and Pb--Pb collisions at $\sqrt{s_{{\rm NN}}}$ = 5.02 TeV...
Heavy quarks are produced in hard partonic scatterings at the very early stage of heavy-ion collisions and experience the whole evolution of the Quark-Gluon Plasma medium. Two-particle femtoscopic correlations at low relative momentum, are sensitive to the final-state interactions and to the space-time extent of the region from which the correlated particles are emitted. Correlations study...
The production yield of (hyper)nuclei is commonly described using two conceptually different models: statistical hadronization (SHM) or coalescence. This talk will present the elliptic flow measurements ($v_{2}$) of $\mathrm{^{3} He}$ and $\mathrm{^{3}_{\Lambda} H}$ at LHC energies using the large Pb-Pb data sample collected by ALICE during the Run 3 of LHC. Results will be compared with the...
We augment the conventional $T$-$\mu_B$ planar phase
diagram for QCD matter by extending it to a multi-dimensional domain spanned by temperature $T$, baryon chemical potential $\mu_B$, external magnetic field $B$ and angular velocity $\omega$. This is relevant for peripheral heavy-ion collisions or astrophysical systems where $B$, $\omega$ are non-zero. Using two independent approaches, one...
