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V. Kireyeu

Publications and source records attributed to V. Kireyeu.

10 recordsLinked to original sources
arXiv2025

Production of protons, deuterons and tritons in argon-nucleus interactions at 3.2 AGeV

Results of the BM@N experiment at the Nuclotron/NICA complex on the production of protons, deuterons and tritons in interactions of an argon beam of 3.2 AGeV with fixed targets of C, Al, Cu, Sn and Pb are presented. Transverse mass spectra, rapidity distributions and multiplicities of protons, deuterons and tritons are measured. The results are treated within a coalescence approach and compared with predictions of theoretical models and with other measurements

hep-ex↗
arXiv2024

Cluster formation near midrapidity -- can the mechanism be identified experimentally?

The formation of weakly bound clusters in the hot and dense environment at midrapidity is one of the surprising phenomena observed experimentally in heavy-ion collisions from a low center of mass energy of a few GeV up to a ultra-relativistic energy of several TeV. Three approaches have been advanced to describe the cluster formation: coalescence at kinetic freeze-out, cluster formation during the entire heavy-ion collision by potential interaction between nucleons and deuteron production by hadronic reactions. We identify experimental observables, which can discriminate these production mechanisms for deuterons.

nucl-th↗
arXiv2021

Properties of the QGP created in heavy-ion collisions

We review the properties of the strongly interacting quark-gluon plasma (QGP) at finite temperature $T$ and baryon chemical potential $μ_B$ as created in heavy-ion collisions at ultrarelativistic energies. The description of the strongly interacting (non-perturbative) QGP in equilibrium is based on the effective propagators and couplings from the Dynamical QuasiParticle Model (DQPM) that is matched to reproduce the equation-of-state of the partonic system above the deconfinement temperature $T_C$ from lattice QCD. Based on a microscopic transport description of heavy-ion collisions we discuss which observables are sensitive to the QGP creation and its properties.

nucl-th↗
arXiv2020

Hadron production in elementary nucleon-nucleon reactions from low to ultra-relativistic energies

We study the hadron production in $p+p$, $p+n$ and $n+n$ reactions within the microscopic Parton-Hadron-Dynamics (PHSD) transport approach in comparison to PYTHIA 8.2. We discuss the details of the "PHSD tune" of the Lund string model (realized by event generators FRITIOF and PYTHIA) in the vacuum (as in $N+N$ collisions) as well as its in-medium modifications relevant for heavy-ion collisions where a hot and dense matter is produced. We compare the results of PHSD and PYTHIA 8.2 (default version) for the excitation function of hadron multiplicities as well as differential rapidity $y$, transverse momentum $p_T$ and $x_F$ distributions in $p+p$, $p+n$ and $n+n$ reactions with the existing experimental data in the energy range $\sqrt{s_{NN}} = 2.7 - 7000$ GeV. We discuss the production mechanisms of hadrons and the role of final state interactions (FSI) due to the hadronic rescattering. We also show the influence of the possible quark-gluon plasma (QGP) formation on hadronic observables in $p+p$ collisions at LHC energies. We stress the importance of developing a reliable event generator for elementary reactions from low to ultra-relativistic energies in view of actual and upcoming heavy-ion experiments.

hep-ph↗
arXiv2020

Parton-Hadron-Quantum-Molecular Dynamics (PHQMD) -- A Novel Microscopic N-Body Transport Approach for Heavy-Ion Collisions, Dynamical Cluster Formation and Hypernuclei Production

Cluster and hypernuclei production in heavy-ion collisions is presently under active experimental and theoretical investigation. Since clusters are weekly bound objects, their production is very sensitive to the dynamical evolution of the system and its interactions. The theoretical description of cluster formation is related to the n-body problem. Here we present the novel n-body dynamical transport approach PHQMD (Parton-Hadron-Quantum-Molecular Dynamics) which is designed to provide a microscopic description of nuclear cluster and hypernucleus formation as well as of general particle production in heavy-ion reactions at relativistic energies. In difference to the coalescence or statistical models, often used for the cluster formation, in PHQMD clusters are formed dynamically due to the interactions between baryons described on a basis of Quantum Molecular Dynamics (QMD)which allows to propagate the n-body Wigner density and n-body correlations in phase-space, essential for the cluster formation. The clusters are identified by the MST (Minimum Spanning Tree) or the SACA ('Simulated Annealing Cluster Algorithm') algorithm which finds the most bound configuration of nucleons and clusters. Collisions among hadrons as well as Quark-Gluon-Plasma formation and parton dynamics in PHQMD are treated in the same way as in the established PHSD (Parton-Hadron-String Dynamics)transport approach. In order to verify our approach with respect to the general dynamics we present here the first PHQMD results for general 'bulk' observables such as rapidity distributions and transverse mass spectra for hadrons ($π, K, \bar K, p, \bar p, Λ, \bar Λ$) from SIS to RHIC energies. We find a good description of the 'bulk' dynamics which allows us to proceed with the results on cluster production, including hypernuclei.

nucl-th↗
arXiv2020

Exploring the partonic phase at finite chemical potential in and out-of equilibrium

We study the influence of the baryon chemical potential $μ_B$ on the properties of the Quark-Gluon-Plasma (QGP) in and out-of equilibrium. The description of the QGP in equilibrium is based on the effective propagators and couplings from the Dynamical QuasiParticle Model (DQPM) that is matched to reproduce the equation-of-state of the partonic system above the deconfinement temperature $T_c$ from lattice QCD. We study the transport coefficients such as the ratio of shear viscosity $η$ and bulk viscosity $ζ$ over entropy density $s$, i.e. $η/s$ and $ζ/s$ in the $(T,μ)$ plane and compare to other model results available at $μ_B =0$. The out-of equilibrium study of the QGP is performed within the Parton-Hadron-String Dynamics (PHSD) transport approach extended in the partonic sector by explicitly calculating the total and differential partonic scattering cross sections based on the DQPM and the evaluated at actual temperature $T$ and baryon chemical potential $μ_B$ in each individual space-time cell where partonic scattering takes place. The traces of their $μ_B$ dependences are investigated in different observables for symmetric Au+Au and asymmetric Cu+Au collisions such as rapidity and $m_T$- distributions and directed and elliptic flow coefficients $v_1, v_2$ in the energy range 7.7 GeV $\le \sqrt{s_{NN}}\le 200$ GeV.

nucl-th↗
arXiv2019

A new review of excitation functions of hadron production in $pp$ collisions in the NICA energy range

Data on hadron multiplicities from inelastic proton-proton interactions in the energy range of the NICA collider have been compiled. The compilation includes recent results from the NA61/SHINE and NA49 experiments at the CERN SPS accelerator. New parameterizations for excitation functions of mean multiplicities $\left<π^{\pm}\right>$, $\left $, $\left $, $\left<Λ\right>$, $\left $, $\left<\bar{p}\right>$ are obtained in the region of collision energies $3<\sqrt{s_{NN}}<31$ GeV. The energy dependence of the particle yields, as well as variation of rapidity and transverse momentum distributions are discussed. A standalone algorithm for hadron phase space generation in pp collisions is suggested and compared to model predictions using an example of the PHQMD generator.

nucl-ex↗
arXiv2019

Parton Hadron Quantum Molecular Dynamics (PHQMD) -- a Novel Microscopic N-Body Transport Approach for Heavy-Ion Dynamics and Hypernuclei Production

We present the novel microscopic n-body dynamical transport approach PHQMD(Parton-Hadron-Quantum-Molecular-Dynamics) for the description of particle production and cluster formation in heavy-ion reactions at relativistic energies. The PHQMD extends the established PHSD (Parton-Hadron-String-Dynamics) transport approach by replacing the mean field by density dependent two body interactions in a similar way as in the Quantum Molecular Dynamics (QMD) models. This allows for the calculation of the time evolution of the n-body Wigner density and therefore for a dynamical description of clusters and hypernuclei formation. The clusters are identified with the MST ('Minimum Spanning Tree') or the SACA ('Simulated Annealing Cluster Algorithm') algorithm which - by regrouping the nucleons in single nucleons and noninteracting clusters - finds the most bound configuration of nucleons and clusters. The selected results on clusters and hypernuclei production from Ref. arXiv:1907.03860 are discussed in this contribution.

nucl-th↗
arXiv2019

The PHQMD model for the formation of nuclear clusters and hypernuclei in heavy-ion collisions

Modeling of the process of the formation of nuclear clusters in the hot nuclear matter is a challenging task. We present the novel n-body dynamical transport approach - PHQMD (Parton-Hadron-Quantum-Molecular Dynamics) [1] for the description of heavy-ion collisions as well as clusters and hpernuclei formation. The PHQMD extends well established PHSD (Parton-Hadron-String Dynamics) approach - which incorporates explicit partonic degrees-of-freedom (quarks and gluons), an equation-of-state from lattice QCD, as well as dynamical hadronization and hadronic elastic and inelastic collisions in the final reaction phase, by n-body quantum molecular dynamic propagation of hadrons which allows choosing of the equation of state with different compression modulus. The formation of clusters, including hypernuclei, is realized by incorporation the Simulated Annealing Clusterization Algorithm (SACA). We present first results from PHQMD on the study of the production rates of strange hadrons, nuclear clusters and hypernuclei in e1elementary and heavy-ion collisions at NICA energies. In particular, sensitivity on the "hard" and "soft" equation of state within the PHQMD model was investigated for "bulk" observables.

nucl-th↗