Description
Note: All contributions are given 12 minutes + 3 min for questions
Measurements of open heavy-flavor hadron production in heavy-ion collisions provide a powerful tool to study both initial-state effects on heavy-quark production and final-state interactions between heavy-quarks and the quark-gluon plasma (QGP). These measurements are performed with the ATLAS detector at the LHC and capitalize on the large statistics of the Run 2 Pb+Pb dataset. This talk...
In a relativistic heavy ion collision, heavy flavor (charm and bottom) quarks are mostly created via hard processes at the early stage of collisions. We present the latest results of the azimuthal anisotropy coefficients v_n for prompt and non-prompt D0 mesons in PbPb, pPb, and pp collisions from the CMS experiment. The studies are about collectivity phenomena in smaller systems (pp and pPb),...
In this talk, the nuclear modification factor ($R_{\rm AA}$) and the elliptic flow ($v_{2}$) of open heavy-flavour hadrons via their hadronic and semileptonic decays to electrons at midrapidity and to muons at forward rapidity in heavy-ion collisions will be discussed. In particular, the latest results on the centrality dependence of $R_{\rm AA}$ of charmed hadrons, beauty-decay electrons,...
With full particle ID, precision tracking, and calorimetry, the LHCb detector is able to measure prompt and non-prompt charm production through a variety of decay channels at forward rapidity. These unique abilities allow LHCb to study a wide range of exotic and conventional open and hidden charm states and their interactions in the QCD medium. Here we will discuss recent LHCb results on charm...
Measurements of jet suppression and modification in heavy-ion collisions provide powerful and broad information on the dynamics of the hot, dense plasma formed in relativistic nucleus-nucleus collisions. In this talk we present measurements of jet energy loss and modification which are performed using the high-statistics Pb+Pb collision data at 5.02 TeV recorded during 2018 with the ATLAS...
Heavy ion collisions at high energies can be used as an interesting way to recreate and study the medium of the quark-gluon plasma (QGP).
We particularly investigate how jets produced in hard binary collisions evolve within a tentative medium and in particular how the jet-particle momentum components $k_T$ orthogonal to the jet
axis are affected.
We evolved the jets within a medium that...
Interactions of high-$p_{T}$ partons with quark-gluon plasma (QGP) result in jet quenching, which is manifest by the suppression of high-$p_{T}$ jet yields and the modification of jet substructure and di-jet acoplanarity distributions.
Several jet quenching phenomena can be measured precisely over a wide range of jet $p_{T}$ using semi-inclusive distributions of charged-particle jets...
The leading order $\alpha_s$ effect in jet quenching corresponds to the broadening of the jet's transverse momentum, due to the multiple interactions with the underlying medium. A complete understanding of momentum broadening is critical for the success of jet quenching phenomenology.
In this talk, we introduce a strategy to quantum simulate single particle momentum broadening in a QCD...
The LHCb detector is a full spectrometer at forward rapidity covering a pseudorapidity range of 2<eta<5. With its excellent vertex resolution, particle identification and tracking capability, the LHCb is able to perform precision measurements down to very low transverse momentum. We present first LHCb results on heavy flavor in lead-lead collisions at 5.02 TeV, including photoproduction of...
Measurements of heavy baryon production in $pp$, $pA$ and $AA$ collisions from RHIC to top LHC energies have recently attracted more and more attention, currently representing a challenge for the heavy-quark hadronization theoretical understanding.
The $\Lambda_c/D^0$ ratio observed in $AA$ collision at RHIC and LHC energies has a value of the order of the unity. The recent experimental...
The production of quarkonia is one of the first proposed probes of the QGP properties in heavy-ion collisions. Since heavy quarks are produced during the early hard partonic collisions, they experience the entire evolution of the fireball. The suppression of quarkonium bound states by the free color charges of the dense deconfined medium, as well as the charmonium regeneration by...
Jet substructure measurements, based on the distribution of constituents within a jet, are able to probe specific regions of QCD radiation phase space for jet showers in vacuum. This powerful capability provides new opportunities to study the dynamics of jet quenching in heavy-ion collisions and to help reveal the micro-structure of the quark-gluon plasma. The ALICE experiment is particularly...
Going beyond the simplified gluonic cascades, we have introduced both gluon and quark degrees of freedom for partonic cascades inside the medium. We then solve the set of coupled evolution equations numerically with splitting kernels calculated for exponential and Bjorken expanding media to arrive at medium-modified parton spectra for quark and gluon initiated jets respectively. Firstly, we...
The strong suppression of high-pT jets in heavy-ion collisions is a result of elastic and inelastic energy loss, suffered by the jet multi-prong collection of color charges that are resolved by medium interactions. We develop a novel analytic framework to study the quenched jet spectrum in which we include many energy-loss-related effects, such as resummation of soft and hard medium induced...
Complementary to jet reconstruction, two-particle correlations in $\Delta\eta$ and $\Delta\varphi$ are used to study jets, in particular their particle composition. While in Pb–Pb collisions this is done to characterize the quark–gluon plasma, pp and p–Pb collisions serve as a reference and are of interest on their own for their input into the understanding of particle production mechanisms....
Jet interactions in a hot QCD medium created in heavy-ion collisions are conventionally assessed by measuring the modification of the distributions of jet observables with respect to the proton-proton baseline. However, the steeply falling production spectrum introduces a strong bias toward small energy losses that obfuscates a direct interpretation of the impact of medium effects in the...
Multi-particle cumulants of azimuthal angle correlations are compelling tools to constrain the initial conditions and probe the properties of the quark-gluon plasma created in the ultrarelativistic heavy-ion collisions at the LHC. However, only very few of them have been measured experimentally and supplemented with corresponding theoretical calculations.
Using a newly developed...
Collective behaviour of final-state hadrons is studied in ep scattering using the H1 and ZEUS detectors at HERA. Measurements of two- and four-particle azimuthal correlations in both DIS and photoproduction are presented. Ridge yields are extracted from fits to two-particle correlations with H1 data. Comparisons of the magnitudes and signs of the first- and second-harmonic of two-particle...
This talk presents ATLAS measurements of collective, flow phenomena in a variety of collision systems, including pp collisions at 13 TeV, Xe+Xe collisions at 5.44 TeV, and Pb+Pb collisions at 5.02 TeV. A new measurement of vn-[pT] correlations in Xe+Xe and Pb+Pb collisions is presented for harmonics n=2, 3, and 4. The correlation between the event-wise average transverse momentum ([pT]) and...
Measurements of anisotropic flow ($v_n$) provide valuable information on the properties of the quark-gluon plasma.
Along with studies of standard flow observables, one can use strong fluctuations of the anisotropic flow for an efficient selection of the events corresponding to a specific initial geometry. Another quantity with unique sensitivity to physical processes in the initial state ...
Heavy quarks are excellent probes to study the initial stages of heavy ion collisions since they are generated in the early times around 0.1 fm/c together with a thermalization time that is comparable to the lifetime of the QGP phase. Ultra-relativistic heavy ion collisions are expected to generate a huge electromagnetic (e.m.) field that is expected to generate a splitting of the directed...
Simulations of peripheral Au+Au collisions at NICA energies was performed in the PHSD transport model. The properties of velocity and vorticity fields, hydrodynamic helicity was studied at different impact parameters and energies. The general structure of velocity field follows the "little bang" pattern which may be quantified by the velocity dependence allowing to extract the "Hubble"...
The SPS Heavy Ion and Neutrino Experiment (NA61/SHINE) studies the properties of hadron production in collisions of beam hadrons and nuclei with fixed hadronic and nuclear targets.
In this talk, I will discuss the space-time evolution of the system of strongly interacting matter created in the collision, studied from the modification of charged pion spectra and $\pi^{+}/\pi^{-}$ ratios by the...
Studies of collisions of light systems, like O–O, are planned at the LHC [1]. In particular, the translation of initial collision geometry with alpha-clustering in O-16 to triangular modulation of elliptic flow is discussed [2,3]. To date there were no measurements, even at lower collision energies, which demonstrated such fine effects of radial flow. However, numerous measurements of...
The primary goal of the ultrarelativistic heavy-ion collision program at the LHC is to study the properties of the quark-gluon plasma (QGP), a state of strongly interacting matter that exists at high temperatures and energy densities. Anisotropic flow, studied using the anisotropy of the momentum distribution of final state particles, is sensitive to the transport properties (i.e., specific...
In the RHIC Beam Energy Scan program, gold nuclei are collided with different collision energies in the range from few to 62.4 GeV. The goals of the program are to explore the onset of QGP creation, locate the critical point of QCD and study dense baryon matter.
In this talk, we report on the first application of 3D Monte Carlo Glauber (GLISSANDO2) and TrENTO p=0 initial states for 3D...
In heavy-ion collisions, the observed non-zero second-order azimuthal anisotropy coefficient $v_2$ of particles with high transverse momenta $p_{\rm T}$ is driven by the path-length dependent energy loss of hard partons traveling in the quark-gluon plasma, known as the jet quenching effect. Recent measurements show also a non-zero $v_2$ value for high-$p_{\rm T}$ charged particles at high...
We propose a new model for a homogeneous description of hadron-hadron and hadron-nucleus collisions, the Gluon Exchange Model (GEM). While technically our model can be regarded as a generalization of the Dual Parton Model by Capella and Tran Thanh Van, it is fundamentally based on the number of exchanged color octets (gluons) and significantly extends the Fock space of states available for the...
W and Z boson measurements provide a clean probe of the hard scatterings taking place in the initial stages of hadronic collisions. In particular, measurements in pp collisions provide a useful reference to test pQCD calculations, while results in p-Pb and Pb-Pb collisions provide a useful insight in the nuclear parton distribution functions (nPDFs) of the involved nuclei. Such observations...
The LHeC and the FCC-he will open a new realm in our understanding of nuclear structure and the dynamics in processes involving nuclei, in an unexplored kinematic domain. In this talk we will review the most recent studies as shown in the update of the 2012 CDR [1]. We will discuss the determination of nuclear parton densities in the framework of global fits and for a single nucleus. Then we...
The study of (anti)nuclei production in hadronic collisions has proven to be a powerful tool to investigate the formation mechanism of loosely bound states. The $^{3}_{\Lambda}\text{H}$ is a bound state of Λ, proton, and neutron characterised by a Λ separation energy of few keV, which leads to a large wave function. As a consequence, the measured (anti-)$^{3}_{\Lambda}\text{H}$ production...
The production of light nuclei in particle collisions can be described as the coalescence of nucleons into nuclei. In most coalescence models used in heavy ion collisions, the probability for coalescence is controlled predominantly by the size of the interaction region, while nucleon momentum correlations may be treated as collective flow or even neglected. Interestingly, recent experimental...
Event-by-event fluctuations of conserved quantities such as electric charge, baryon number and strangeness in ultrarelativistic heavy-ion collisions provide insight into the properties of the quark-gluon plasma and the QCD phase diagram. The net-charge fluctuations in finite phase space are usually studied using the $\nu_{dyn}$ observable, which is robust against the detection efficiency...
NA61/SHINE is a multipurpose fixed-target facility at the CERN Super Proton Synchrotron. The main goals of the NA61/SHINE strong-interactions program are to discover the critical point of strongly interacting matter as well as to study the properties of produced particles relevant for the study of the onset of deconfinement - the transition between the state of hadronic matter and the...
Hadronic resonances with different lifetimes are very useful to probe the hadronic phase, the latest stage in the evolution of the system created in heavy-ion collisions. Due to their relatively short lifetimes compared to the duration of the hadronic phase, resonances are good candidates to investigate the interplay between particle rescattering and regeneration. In addition, the measurement...
In ultra-relativistic heavy-ion collisions, one expects copious rates of $\gamma+\gamma$ processes through the interaction of the large electromagnetic fields of the nuclei which can lead to light-by-light scattering via loop diagrams. This process was directly observed for the first time in UPCs at the LHC by ATLAS. Final measurements of light-by-light scattering with full run 2 dataset with...
Ultrarelativistic Heavy Ions of large charge Z are accompanied by a large flux of Weizsacker–Williams photons. This opens up the opportunity to study a variety of single photon induced nuclear processes, as well as photon-photon processes.
We would like to present a formalism which allows to calculate differential distributions of dileptons produced via photon-photon fusion in semi-central...
Relativistic heavy ion beams are accompanied by a large flux of equivalent photons, giving rise to a set of photon-induced processes. These can lead to photon-photon interactions in both ultraperipheral collisions, where the nuclei do not overlap, as well as in hadronic processes accompanied by the production of hot, dense matter. The latter provides a potentially sensitive electromagnetic...
The ultra-peripheral collisions (UPCs) of relativistic heavy ion beams lead to a diverse set of photon-nucleus interactions. The measurements of particles and their interaction produced in photo-nuclear reactions can shed light on the QCD dynamics of novel, extremely asymmetric colliding systems, with energies between those available at RHIC and the LHC. Understanding the hadronic fluctuation...
The medium modification in energies of kaon and antikaon at zero momentum in strongly magnetized asymmetric nuclear matter are explored using a chiral $\text{SU(3)}$ model. The parameters used in this calculation are fitted to nuclear matter saturation properties and with vacuum masses of baryon. We have investigated the possibility of antikaon condensation in neutron star with charge...
Many effective models of strong interactions predict the first-order phase transition between the hadronic matter and quark-gluon plasma. One of the main approaches to search for it is based on the study of fluctuations of e.g. net-baryon number, net-charge, or net-strangeness number measured in relativistic heavy-ion collisions. Such fluctuations are often quantified by cumulants or factorial...
Color Glass Condensate is a powerful theoretical tool that is able to describe the dynamical properties of partons in the QCD non-perturbative regime, characterized by strong color fields and high parton density.
A previous study, performed for a wide range of energies measured at the Relativistic Heavy Ion Collider (RHIC) and at the Large Hadron Collider (LHC), has shown that observables...
We predict that triangle singularities of hadron spectroscopy can be strongly affected in heavy ion collisions. To do it we examine various effects on the singularity-inducing triangle loop of finite temperature in the terminal hadron phase.
It appears that peaks seen in central heavy ion collisions are more likely to be hadrons than rescattering effects under two conditions. First, the...
Jet charge is the momentum weighted sum of the electrical charges of jet constituents. This value is sensitive to the charge of the parton that initiates the jet. However, jet charge distributions depend strongly on the choice of parameters for the jet, namely, jet radius, minimum $p_{T , jet}$. This poster presents the measurement of jet charge for proton-proton collisions at $\sqrt{s_{NN}} =...
Physics of ultraperipheral ultrarelativistic heavy-ion collisions gives an excellent opportunity to study photon-photon interaction. Vast moving charged particles are surrounded by an electromagnetic field that can be considered as a source of (almost real) photons. The photon flux scales as the square of the nuclear charge, so $^{208}$Pb has a considerable advantage over protons as far as the...
Measurements of heavy-flavour meson and baryon production in proton-proton (pp) collisions are crucial to study the charm quark hadronisation mechanisms and the possible difference with respect to $e^+e^-$ collisions. Measurements in p-Pb collisions are also important to investigate the role of the cold nuclear matter (CNM) effects. Furthermore, measurements in both collision systems provide...
High-energy heavy-ion collisions produce a state of strongly-interacting matter characterised by high energy density and temperature. In these extreme conditions, according to quantum chromodynamics (QCD) calculations on the lattice, matter undergoes a phase transition to a quark--gluon plasma (QGP) state in which quarks and gluons are deconfined.
The production of strange quarks in...
The final stage of a relativistic heavy-ion collision is a hadron gas. Final-state interactions therein distort the p_t spectrum of particles coming from the phase transition upon cooling the quark-gluon plasma.
Using recent state of the art parametrizations of pion interactions by Ruiz de Elvira and Peláez we provide theoretical computations of the pionic depth of the gas: how likely is it...
HYDJET++ is a Monte Carlo event generator merging parametrized soft part inspired by hydrodynamics with hard part containing jets. It has been successful to describe particle production in Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV energies. In this poster we present for the first time the particle spectra and collective flow for top LHC energy $\sqrt{s_{NN}}=5.02$ TeV Pb+Pb collisions....
One of the main goals of the relativistic nuclear collisions studies is to investigate the behavior of nuclear matter under extreme conditions of temperature and energy density. Strange and multi-strange hadrons can provide valuable information related to the properties of the created system and the onset of deconfinement. The energy and centrality dependence of the effective temperatures...
The quark-gluon plasma (QGP), produced in relativistic heavy-ion collisions, freeze-out through multi-partonic interactions to final state hadrons. The transverse momentum ($p_{\rm T}$) spectra study of the produced particles can ighten the thermodynamical properties of the QGP medium. In this work, a detailed study of the $p_{\rm T}$ spectra of the identified charged particles (pions, kaons,...
In the framework of PYTHIA8.2 program we considered p-Pb and p-Au heavy ion collisions at the energy of 5.02 TeV and 8 TeV. The advantage of this program is in the combining of several nucleon-nucleon collisions into one heavy ion collision, based on phenomenological treatment of a hadron as a vortex line in a colour superconducting medium, the consistent treatment of the central rapidity...
Comparing particle production in Pb–Pb and p–Pb collisions with pp collisions provides insight into the longitudinal (and low-x) nature of the hot and dense medium created in heavy-ion collisions. Investigating the system-size dependence of the particle production at the same collision energy is particularly important, as one can then directly study effects of the nuclear geometry. ALICE has...
The search for experimental signatures of the critical point (CP) of strongly interacting matter is one of the main objectives of the NA61/SHINE experiment at CERN SPS. In the course of the experiment, a beam momentum (13A – 150A GeV/$c$) and system size (p+p, p+Pb, Be+Be, Ar+Sc, Xe+La, Pb+Pb) scan is performed. Local proton density fluctuations in transverse momentum space represent an order...
