The modifications of basic properties of hadrons inside a hot and dense nuclear matter are a consequence of the partial restoration of the chiral symmetry and are an intensively studied topic for the last 30 years [1]. Whereas the effects for K$^+$ and K$^0_S$ appear to be theoretically more straightforward and experimentally established [2,3], it seems not to be the case for K$^–$. A series...
Suppression of the production yield of $\Upsilon$ states in heavy-ion collisions relative to expectation from p+p collisions is a tool for studying the properties of quark-gluon plasma. Such suppression is expected to be caused by Debye-like screening of color charges happening at a high temperature in the plasma. In order to correctly interpret this effect, the $\Upsilon$ production mechanism...
The expected increase in the integrated luminosity foreseen for the LHC Runs 3 and 4, combined with the performance of the upgraded ALICE detector, will allow for the measurement of the production of rare light-flavour probes such as (anti)nuclei and exotic states. Not only are these important probes of the system created in high-energy proton-proton (pp) and heavy-ion collisions, but also...
The expansion of the matter formed in nucleus-nucleus collisions at relativistic energies produces a collective transverse flow. This flow is the response to the density gradients in the initial fireball. It is azimuthally asymmetric because the initial fire-ball is anisotropic and contains hot spots. These inhomogeneities are of particular interest for two reasons. They reflect the poorly...
The study of the interaction of heavy quarks with the constituents of the medium created in heavy-ion collisions provides important information about the characteristics of the Quark-Gluon Plasma (QGP). The production of heavy quarks occurs prior to the formation of the QGP, implying that they experience the entire evolution of the system. To infer the properties of the partonic interactions...
The ALICE experiment at the Large Hadron Collider (LHC) is dedicated to study the prop- erties of the Quark-Gluon Plasma (QGP), a de-confined partonic state of strongly-interacting matter formed in relativistic heavy-ion collisions. Heavy quarks (charm and beauty), produced by parton-parton hard scatterings in the early stages of such collisions, are considered to be effective probes to study...
One of the most common assumptions when calculating radiative energy loss of high $p_{\perp}$ particles in quark-gluon plasma is the soft-gluon approximation, which considers that initial parton losses only a small amount of its energy via gluon's bremsstrahlung. Despite its convenience, the approximation sustainability was questioned by the reported notable radiative energy loss within...
Strangeness enhancement has been observed in high-multiplicity proton-proton (pp) collisions at the LHC for several multi-strange hadrons and shown to be in remarkable agreement with the measurements performed in p-Pb collisions. Resonance particles with different lifetimes can provide an interesting insight into the properties of the hadronic phase in high-multiplicity proton-proton (pp)...
HADES provides a large acceptance combined with a high mass-resolution and therefore allows to study dielectron and hadron production in heavy-ion collisions with unprecedented precision. The high statistics measurements of flow coefficients for protons, deuterons and tritons in Au+Au collisions at 1.23 AGeV (performed with the HADES experiment at SIS18/GSI) are presented here. In addition to...
We report on results of fitting pt spectra of identified particles with the blast-wave model with included resonances and chemical potentials according to the model of partial chemical equilibrium. Bayesian technique with Gaussian emulator is used in the fitting procedure. Spectra from the RHIC BES programme and LHC are included in the analysis. For central collisions, the freeze-out...
Heavy quarks are produced in hard scattering processes during the early stages of a heavy-ion collision at ultra-relativistic energies. Their annihilation rate is negligible, and they participate in the whole medium evolution losing their energy via radiative and collisional processes while traversing through the Quark-Gluon Plasma (QGP) formed in such collisions. This allows us to study the...
The novel microscopic n-body dynamical transport approach PHQMD (Parton-Hadron-Quantum-Molecular-Dynamics) extends the established PHSD (Parton-Hadron-String-Dynamics) transport approach by introducing n-body quantum molecular dynamic type propagation of hadrons and by allowing to choose the equations of state with different compression modulus.
We present first results of the study on the...
The BM@N (Baryonic Matter at Nuclotron) is the first working fixed-targeted experiment at the Nuclotron-based Ion Collider fAсility (NICA). The properties of hadrons and formation of (multi-)strange hyperons will be studied at BM@N. Also, the experiment involves the searching of hypernuclei.
In 2018 a new topic was added to the BM@N physics program - the studies of Short Range Correlations...
The Compressed Baryonic Matter (CBM) experiment will access a wide range of physics observables for heavy-ion collisions in the regime of highest net-baryon densities. Two of the core topics of its physics program are on one hand the measurement of dilepton production and on the other hand the study of hypernuclei, which were both not measured before with other experiments in this energy...
We will present our newly developed DREENA framework [1], which allows predicting energy loss of high $p_{\perp}$ partons traversing quark gluon plasma (QGP). DREENA framework is based on state-of-the-art dynamical energy loss formalism, which takes into account finite size medium composed of dynamical (that is moving) constituents. In DREENA-B, this formalism is applied to 1+1D Bjorken medium...
In the talk the phase structure of the dense baryonic/quark matter has been investigated in the presence of baryon, isospin, chiral and chiral isospin chemical potentials in the framework of Nambu--Jona-Lasinio model. It has been shown that in the large-Nc limit there exist several dualities of the phase portrait. One of the key conclusions of our studies is the fact that chiral imbalance...
Heavy quarks are produced in the early stages of relativistic heavy-ion collisions via initial hard scatterings. Therefore, they are considered as effective probes of the hot and dense Quark-Gluon Plasma (QGP) formed in such collisions since they witness its full evolution. In pp collisions, the measurement of charm and beauty hadron production cross sections can be used to test our...
The study of hadronic resonance production provides a unique tool to investigate the interplay of re-scattering and regeneration effects in the hadronic phase of heavy-ion collisions. The $\phi$ meson has a longer lifetime compared to other resonances. Thus, it is expected that its production will not be affected by regeneration and re-scattering processes. Measurements in small collision...
The possible correlation between the yield of strange and heavy-flavour particles and the emission of particles in the region outside pN-kinematics (the so-called cumulative region) in pA collisions is studied. The particle production in the cumulative area is considered as a trigger, confirming participation in the process of a dense few-nucleon cluster. From the modern point of view this...
We report on the inclusive production of the f$_{0}$(980) particle measured at midrapidiy in inelastic pp collisions at $\sqrt{s}$ = 5.02 TeV with ALICE.
The nature of the f$_0$(980) remains elusive: different interpretations of this resonance including $\mathrm{q}\overline{\mathrm{q}}$ states, loosely-bound molecular states such as $\mathrm{K}\overline{\mathrm{K}}$, and as a tetra quark...
Two-particle correlations can be used to probe the strong interaction between nucleons and multi-strange baryons. We will show measurements of correlation functions of proton-$\Xi^−$ pairs in p-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV, and proton-$\Omega^−$ pairs produced in high-multiplicity pp collisions at $\sqrt{s}$ = 13 TeV. Utilising newly developed femtoscopic techniques, we will...
The conditions of production and freeze-out of strange particles in central heavy-ion collisions at energies of NICA and FAIR are studied within two microscopic transport models. The system of final particles can be sub-divided into a core, containing the still interacting particles, and a halo with particles already decoupled from the system. In microscopic calculations hadrons are...
When traversing QCD medium, high $p_{\perp}$ partons lose energy, which is measured by suppression, and also predicted by various energy loss models. A crucial test of different energy loss mechanisms is their dependence on the medium temperature. Though it is commonly assumed that this dependence is cubic, different effects such as Debye screenings, finite parton masses, infrared cutoffs,...
In ultra-relativistic heavy-ion collisions, where the formation of a high-density colour-deconfined medium, the Quark-Gluon Plasma (QGP), is expected, heavy quarks are considered as an effective probe for investigating the properties of such a medium. Indeed, they are produced in scattering processes with large momentum transfer in the early stage of the collision and traverse the medium while...
The ALICE Collaboration is preparing a major upgrade of the detector apparatus during the second LHC long shutdown (LS2, 2019-20) in view of the LHC Runs 3 and 4 (2021 to 2029).
The objective of the ALICE upgrade for LS2 is two-fold: i) an improvement of the tracking precision and efficiency, in particular in the low-momentum range; ii) an improvement of the readout capabilities of the...
In the exploration of the phase diagram of strong nuclear force, some of the most intriguing questions are associated with the phase dubbed Quark-Gluon Plasma (QGP). One of the most successful programs in ultra-relativistic nuclear collisions for the studies of QGP properties are the analyses of anisotropic flow phenomenon with correlation techniques. Many additional insights about QGP...
The extreme energy densities reached in Pb-Pb collisions at the LHC lead to a significant production of baryon states. Among the thousands of particles produced, light (anti-)hypernuclei are of special interest: their wide wave function and extremely low binding energy make them sensitive to the conditions created in high energy collisions. The study of their production can shed light on the...
Properties of nuclear matter can be studied by relativistic heavy-ion collisions in high energy experiments like the STAR experiment. One of the methods to learn something about this matter is the femtoscopy, which relies on information carried by the particles produced in the collisions. Using correlation functions, the source parameters, such as space-time characteristics, are provided. The...
The X-ray measurements of kaonic atoms play an important role for
understanding the low-energy QCD in the strangeness sector. The energy shift
and broadening of the lowest-lying states of
such atoms, induced by the kaon-nucleus strong interaction, can be
determined with high precision from atomic X-ray spectroscopy.
Significant achievements have been obtained by the SIDDHARTA experiment...
Low-mass dimuon production, including pairs from the light neutral mesons $\eta$, $\rho$, $\omega$ and $\varphi$, provide key information on the hot and dense state of strongly interacting matter produced in ultra-relativistic heavy-ion collisions. The properties of this medium and its effect on particle production, such as the strangeness enhancement and chiral symmetry restoration, can be...
Hadronization in the non-extensive statistical approach can be described well, by the Tsallis-Pareto based fragmentation Functions [1]. We investigate the mass scaling of the fragmentation parameters in case of massive identified hadron production, like in Ref [2,3]. We present the comparison of global cross section and channel contributions as well.
[1] Á. Takács & G.G. Barnaföldi: ...
The Combustion adiabat (CA) or the Chapman-Jouget adiabat equation can be useful tool to study the phase transition (PT) of a neutron star (NS) to a quark star (QS).
CA is a relation connecting the initial and final state of matter across a shock or a combustion discontinuity, where the initial and the final state belong to different equation of state (EoS).
In this problem we assume the...
In the ultra-relativistic heavy-ion collisions at the CERN Large Hadron Collider (LHC), a state of matter, called Quark-Gluon Plasma (QGP), is created.
Heavy quarks, like charm and beauty, are a powerful tool to investigate the medium formed in these collisions. They are produced in hard partonic scattering processes, which occur on a timescale shorter than the QGP formation time. They...
Open-charmed mesons are unique tools to study the properties of the Quark-Gluon Plasma (QGP) formed in ultra-relativistic nucleus-nucleus collisions. Charm quarks, due to their large mass, are produced in hard partonic scattering processes in the initial stages of the collision. Therefore, they experience all the phases of the QGP evolution propagating through the medium and losing energy...
The Quark-Gluon Plasma (QGP) is a deconfined state of strongly-interacting matter that is produced at the Large Hadron Collider (LHC) via ultra-relativistic heavy-ion collisions. The QGP properties can be investigated by studying the kinematic features of final-state hadrons containing charm or beauty quarks. Heavy quarks are mainly produced in hard scattering processes among partons, that...
Electroweak bosons are created in the hard scattering processes at the initial stage of heavy-ion collisions and they are insensitive to the presence of the strongly-interacting medium. This makes them clean probes of the initial-state effects in heavy-ion collisions, such as the nuclear modification of the Parton Distribution Functions (nPDFs). Furthermore, their measurement in heavy-ion...
Short-lived resonances play an important role to understand the mechanism of particle production and the hadronic phase properties of heavy-ion collisions. Resonance yields are modified due to the interaction of their decay daughters within the hadronic medium via the processes like re-scattering and regeneration. p-Pb collision is a suitable system to study the multiplicity dependence of the...
Heavy quarks (charm and beauty) are produced in the early stages of hadronic collisions via hard scattering processes and therefore are efficient probes to study the properties of the Quark-Gluon Plasma produced in heavy-ion collisions at the LHC. Charged-particle multiplicity gives information on the global characteristics of the event and can be exploited to investigate the possible...
J/$\psi$ mesons have long been proposed as ideal probes capable of providing evidences of the formation of Quark--Gluon Plasma (QGP) in ultra-relativistic heavy-ion collisions. Various Cold Nuclear Matter (CNM) effects are however expected to affect J/$\psi$ production in addition to the modifications due to the presence of the QGP, and the study of p--Pb collisions represents a crucial tool...
The study of production of particles which contain heavy quarks (charm and beauty) provides an exceptional tool to investigate the characteristics of the hot and dense QCD medium, the Quark-Gluon Plasma (QGP), created in ultra-relativistic heavy-ion collisions. In particular, heavy-flavour measurements allow one to study the basic properties of this medium, like its energy density, and to...
Short-lived resonances are powerful probes to understand the hadronic phase in ultra-relativistic heavy-ion collisions, due to their lifetimes of $\sim$10 fm/c, comparable to the time span between chemical and kinetic freeze-out. The measurements of short-lived resonances in pp collisions provide the baseline for heavy-ion collisions measurement. In this respect, we present the multiplicity...
In the ultra-relativistic heavy-ion collisions provided at the LHC nuclear matter undergoes, under extreme conditions of high temperature and high energy density, a transition to a phase in which quarks and gluons are deconfined: the Quark-Gluon Plasma (QGP). Unlike up and down quarks, which form ordinary matter, strange quarks are not present as valence quarks in the initial state and they...
Heavy-flavour production studies in pp collisions, besides providing the necessary baseline for measurements in Pb$-$Pb collisions, constitute a precision test of perturbative QCD calculations. In complex systems such as p$-$Pb collisions, it gives insights into the cold nuclear matter (CNM) effects and also characterizes the nuclear parton distribution functions in the low-$\it{x}$ region,...
Multipomeron model for strange particle production in heavy-ion collisions
G. A. Feofilov, V. N. Kovalenko, A. M. Puchkov, F. F. Valiev
(Saint-Petersburg State University)
The generalized multi-pomeron exchange model \cite{1} - \cite{5} is proposed for the production in high energy heavy-ion collisions of hadrons containing heavy quarks. The main feature of this approach is the effective...
Heavy ions collisions, astronomical observations of neutron stars and their collisions, ab-initio lattice QCD calculations cover only small fractions of QCD phase diagram, leaving the phase structure of QCD still unclear. We propose a unified flavour SU(3) phenomenological model for the QCD thermodynamics with all known hadrons and u,d, and s quarks as degrees of freedom. The model...
The heavy-flavor quarks (charm, beauty) play an important role in probing the Quark-Gluon Plasma (QGP) formed in the heavy-ion collisions. They are produced in hard partonic scattering processes, and have shorter formation time than the QGP. As a result, they experience all the phases of the plasma evolution propagating through the QGP and losing energy interacting with its constituents....
We propose to use the entropy-per-baryon number ratio as a clear signal for a first-order phase transition in heavy-ion collisions. Our study uses the chiral fluid dynamics model, coupling the nonequilibrium dynamics of the chiral order parameter to an expanding quark fluid. As the system is driven out of equilibrium, dissipation and noise lead to a significant increase in entropy during the...
The coherent inelastic processes of the type $a \rightarrow b$, which may take place in the interaction of hadrons and $\gamma$ quanta with nuclei at very high energies (the nucleus remains the same, and its quantum state does not change), and - in particular - may lead to the production of strange and heavy-flavor mesons and baryons, are theoretically investigated. For taking into account the...
The phenomenological structure of inclusive cross-sections of the production of two neutral $K$ mesons in hadron--hadron, hadron--nucleus and nucleus--nucleus collisions is theoretically investigated taking into account the strangeness conservation in strong and electromagnetic interactions. Relations describing the dependence of the correlations of two short-lived and two long-lived neutral...
The study of open charm meson production provides an important tool for detailed investigations of the properties of hot and dense matter formed in nucleus-nucleus collisions. In particular, charm meson data is of vivid interest in the context of the phase-transition between confined hadronic matter and the quark-gluon plasma as well as it is needed for interpretation of data on J/$\psi$ ...
In this contribution the results of a study of charged pion production at SIS18 energies using the HADES spectrometer at GSI will be presented. The main focus will be on 40% most central Au+Au collisions at $\sqrt{s_{\rm{NN}}}=2.4$ GeV. At this energy matter gets compressed to densities of about two to three times the normal nuclear matter density ($\rho_{0}$) and the maximum temperature...
The QCD phase transition is studied within the thermodynamic geometry. Through the definition of a metric in the thermodynamic space, one builds a scalar thermodynamic geometry curvature, $R$, in the usual way and investigates the nature of the interactions. $R$, indeed, reflects some important features of the system: e.g. the so-called interaction hypothesis, $|R|\sim \xi^d$, where $\xi$ is...
When partons traverse the Quark-Gluon Plasma (QGP), they lose energy via collisional and radiative processes. This manifests in a suppression of the measured jet yield and a modification of the jet fragmentation pattern in heavy-ion collisions relative to proton-proton collisions, for which no QGP is expected to form. The amount of energy that is lost is expected to depend on the respective...
The behavior of strange matter in the frame of the SU(3) Polyakov-loop extended Nambu-Jona-Lasinio model is considered. We discuss the appearance of a peak in the ratio of the number of strange mesons to non-strange mesons known as the "horn". We showed that the rise in the ratio $K^+/\pi^+$ appears in PNJL model when we build the $K^+/\pi^+$ ratio along the phase transition diagram. We...
The yields of strange hadrons: $K_s^{0}$ -meson, $\Lambda^-$ and $\bar{\Xi}$ -hyperon produced in proton-proton ($pp$) and proton-nucleus ($pPb$) collisions at $\sqrt{s_{NN}}= 7 \,TeV$ (in rapidity interval of $|y| < 2$ and traverse momentum range of $0 < p_{T} < 10 \, GeV/c$) as a function of $p_T$ are presented. The simulation codes, $EPOS 1.99$, $EPOS-LHC$ and $QGSJETII-04$ are used as...
At the Large Hadron Collider light (anti-)nuclei are significantly produced in proton-proton
(pp), proton-lead (p-Pb) and lead-lead (Pb-Pb) collisions.
The production mechanism of light (anti-)nuclei is an open question in high energy
physics. The measurement of the production spectra and yields allows to improve our
understanding of the late stages in the evolution of high energy collisions....
Hadronic resonances with lifetimes of a few fm/$c$, shorter than or comparable to the timescale of the fireball evolution are sensitive probes of the dynamics and properties of the medium formed after the hadronisation of the QGP. Because of their short lifetimes, they can decay within the hadronic medium, which can alter or destroy the correlation among the decay daughters via interactions...
Transport properties of the quark-gluon plasma in a hot and dense QCD medium have been studied. We have calculated transport coefficients for massive interacting quasi-particles with non-zero widths described by the Dynamical Quasi-Particle Model(DQPM). The DQPM enable to calculate the quark and gluon collisional interaction rates using the cross-sections. The shear and bulk viscosities have...
Due to the high particle multiplicities produced in Pb-Pb collisions, low-energy jets are difficult to be reconstructed using standard jet algorithms. Two-particles correlations in $\Delta\eta$ and $\Delta\varphi$ can instead be used to study jets, their properties and their particle composition. In this work, two-particle correlations between a high-momentum $K^{0}_{S}$ meson, $\Lambda$...
We investigate the production of Ξ(1820) baryons in pp collisions at 13 TeV by reconstructing their Λ-Κ decays. Recent lattice calculations on parity doubling indicate that the masses of negative-parity particles, such as Ξ(1820), may decrease at high temperatures, while the masses of positive-parity partners, i.e. the Ξ(1530), do not. Furthermore, the lifetime of the Ξ(1820) is short enough...
Simulations of peripheral Au+Au collisions at NICA energies are performed in the PHSD transport model. The properties of velocity and vorticity fields, hydrodynamic helicity are studied at different impact parameters. The general structure of velocity field follows the ”little bang” pattern which may be quantified by the velocity dependence allowing to extract the ”little Hubble” constant....
