scholarly journals Exploring hot and dense QCD matter with HADES

2020 ◽  
Vol 1643 (1) ◽  
pp. 012012
Author(s):  
Georgy Kornakov
Keyword(s):  
Chemical Potential ◽  
Thermal Emission ◽  
Heavy Ion ◽  
Nucleon Nucleon ◽  
Baryon Chemical Potential ◽  
Qcd Phase Diagram ◽  
Test Models ◽  
Particle Spectra ◽  
Strangeness Content ◽  
Dilepton Spectrum

Abstract Experiments at snn s NN = 2 − 3 3 GeV provide the lowest energy point of the global effort made by the heavy-ion community in order to map the QCD phase diagram. This correspond to the highest baryon chemical potential, 700-900 MeV according to the universal freeze-out curve, and temperatures of the fireball of 60-80 MeV. The formed matter can be characterized in terms of particle spectra, fluctuations and correlations. The dilepton spectrum is dominated by thermal emission from the medium and it is sensitive to in medium hadron properties. Strangeness production occurs below the free nucleon-nucleon threshold and it is a sensitive probe to test models of strangeness propagation in matter and its coupling to baryons. Data show a common scaling of measured yields as a function of number of participating nucleons independently on the strangeness content or mass of the hadron. Strangeness propagation in cold nuclear matter produced in pion induced reactions on heavy and light targets shows a significant absorption of negative kaons in heavy targets as well as a similar behaviour of ϕ indicating a strong coupling of ϕ with nucleons. Two-pion correlations, flow harmonics, fluctuations are explored as well in order to further pin down the properties of the created matter.

scholarly journals Using the Linear Sigma Model with quarks to describe the QCD phase diagram and to locate the critical end point

2018 ◽  
Vol 172 ◽  
pp. 08002
Author(s):  
Alejandro Ayala ◽  
Jorge David Castaño-Yepes ◽  
José Antonio Flores ◽  
Saúl Hernández ◽  
Luis Hernández
Keyword(s):  
Phase Diagram ◽  
Critical Temperature ◽  
Sigma Model ◽  
Chemical Potential ◽  
Linear Sigma Model ◽  
Transition Line ◽  
Baryon Chemical Potential ◽  
First Order ◽  
Qcd Phase Diagram ◽  
Crossover Transition

We study the QCD phase diagram using the linear sigma model coupled to quarks. We compute the effective potential at finite temperature and quark chemical potential up to ring diagrams contribution. We show that, provided the values for the pseudo-critical temperature Tc = 155 MeV and critical baryon chemical potential μBc ≃ 1 GeV, together with the vacuum sigma and pion masses. The model couplings can be fixed and that these in turn help to locate the region where the crossover transition line becomes first order.

scholarly journals Hadron Resonance Gas EoS and the Fluidity of Matter Produced in HIC

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Guruprasad Kadam ◽  
Swapnali Pawar
Keyword(s):  
Mass Spectrum ◽  
Chemical Potential ◽  
Heavy Ion ◽  
Baryon Chemical Potential ◽  
Hadron Mass ◽  
Lattice Quantum ◽  
Hadron Gas ◽  
Ion Collision ◽  
Discrete Mass ◽  
The Ideal

We study the equation of state (EoS) of hot and dense hadron gas by incorporating the excluded volume corrections into the ideal hadron resonance gas (HRG) model. The total hadron mass spectrum of the model is the sum of the discrete mass spectrum consisting of all the experimentally known hadrons and the exponentially rising continuous Hagedorn states. We confront the EoS of the model with lattice quantum chromodynamics (LQCD) results at finite baryon chemical potential. We find that this modified HRG model reproduces the LQCD results up to T=160 MeV at zero as well as finite baryon chemical potential. We further estimate the shear viscosity within the ambit of this model in the context of heavy-ion collision experiments.

scholarly journals Strangeness at high μB: Recent data from FOPI and HADES

2018 ◽  
Vol 171 ◽  
pp. 02001
Author(s):  
Yvonne Leifels
Keyword(s):  
Experimental Data ◽  
Cross Sections ◽  
Particle Production ◽  
Chemical Potential ◽  
Good Description ◽  
Branching Ratio ◽  
Heavy Ion ◽  
Nuclear Medium ◽  
Strangeness Production ◽  
Baryon Chemical Potential

Strangeness production in heavy-ion reactions at incident energies at or below the threshold in NN collisions gives access to the characteristics of bulk nuclear matter and the properties of strange particles inside the hot and dense nuclear medium, like potentials and interaction cross sections. At these energies strangeness is produced in multi-step processes potentially via excitation of intermediate heavy resonances. The amount of experimental data on strangeness production at these energies has increased substantially during the last years due to the FOPI and the HADES experiments at SIS18 at GSI. Experimental data on K+ and K0 production support the assumption that particles with an s quark feel a moderate repulsive potential in the nuclear medium. The situation is not that clear in the case of K-. Here, spectra and flow of K- mesons is influenced by the contribution of ø mesons which are decaying into K+K- pairs with a branching ratio of 48.9 %. Depending on incident energy upto 30 % of all K- mesons measured in heavyion collisions are originating from ø-decays. Strangeness production yields - except the yield of Ξ- are described by thermal hadronisation models. Experimental data not only measured for heavy-ion collisions but also in proton induced reactions are described with sets of temperature T and baryon chemical potential μb which are close to a universal freeze-out curve which is fitting also experimental data obtained at lower baryon chemical potential. Despite the good description of most particle production yields, the question how this is achieved is still not settled and should be the focus of further investigations.

Mapping the QCD phase diagram with susceptibilities of conserved charges within Nambu–Jona-Lasinio model

2017 ◽  
Vol 32 (11) ◽  
pp. 1750061 ◽  
Author(s):  
Wenkai Fan ◽  
Xiaofeng Luo ◽  
Hong-Shi Zong
Keyword(s):  
Strange Quark ◽  
Collision Energy ◽  
Chemical Potential ◽  
Baryon Number ◽  
Baryon Chemical Potential ◽  
Experiment Data ◽  
High Collision Energy ◽  
Qcd Phase Diagram ◽  
Strange Quark Mass ◽  
Different Temperatures

We evaluate the second to fourth-order baryon, charge and strangeness susceptibilities near a chiral critical point using the Nambu–Jona-Lasinio model under different temperatures and baryon chemical potential. Baryon number susceptibilities are found to be of the greatest magnitude, offering the strongest signal. Whereas the strangeness susceptibilities have the smallest divergence dominating area, owing to the large strange quark mass. We also make an attempt to compare our results with experiment data. The trend at high collision energy is found to be consistent between theory and experiment. The model calculation predicts more complex behavior at low collision energies, near the postulated critical end point.

scholarly journals Chiral phase transition and kaon-to-pion ratios in the entanglement SU(3) PNJL model

2020 ◽  
Vol 229 (22-23) ◽  
pp. 3517-3536
Author(s):  
D. Blaschke ◽  
A. V. Friesen ◽  
Yu. L. Kalinovsky ◽  
A. Radzhabov
Keyword(s):  
Chemical Potential ◽  
Pion Mass ◽  
Heavy Ion ◽  
Bose Condensation ◽  
Chiral Phase ◽  
Qcd Phase Diagram ◽  
Scattering States ◽  
Meson Pole ◽  
Quark Models ◽  
Ion Collision

AbstractWithin the three-flavor PNJL and EPNJL chiral quark models we have obtained pseudoscalar meson properties in quark matter at finite temperature T and baryochemical potential μB. We compare the meson pole (Breit-Wigner) approximation with the Beth-Uhlenbeck (BU) approach that takes into account the continuum of quark-antiquark scattering states when determining the partial densities of pions and kaons. We evaluate the kaon-to-pion ratios along the (pseudo-)critical line in the T − μB plane as a proxy for the chemical freezeout line, whereby the variable x = T∕μB is introduced that corresponds to the conserved entropy per baryon as initial condition for the heavy-ion collision experiments. We present a comparison with the experimental pattern of kaon-to-pion ratios within the BU approach and using x-dependent pion and strange quark potentials. A sharp “horn” effect in the energy dependence K+∕π+ ratio is explained by the enhanced pion production at energies above √sNN=8 GeV, when the system enters the regime of meson dominance. This effect is in line with the enhancement of low-momentum pion spectra that is discussed as a precursor of the pion Bose condensation and entails the occurrence of a nonequilibrium pion chemical potential of the order of the pion mass. We elucidate that the horn effect is not related to the existence of a critical endpoint in the QCD phase diagram.

scholarly journals Effects of Superstatistics on the Location of the Effective QCD Critical End Point

2019 ◽  
Vol 64 (8) ◽  
pp. 665
Author(s):  
A. Ayala ◽  
M. Hentschinski ◽  
L. A. Hernández ◽  
M. Loewe ◽  
R. Zamora
Keyword(s):  
Phase Diagram ◽  
Chemical Potential ◽  
Heavy Ion ◽  
Relativistic Heavy Ion Collisions ◽  
Chiral Symmetry Restoration ◽  
Interaction Volume ◽  
Qcd Phase Diagram ◽  
End Point ◽  
Ion Collisions ◽  
Effective Description

Effects of the partial thermalization during the chiral symmetry restoration at the finite temperature and quark chemical potential are considered for the position of the critical end point in an effective description of the QCD phase diagram. We find that these effects cause the critical end point to be displaced toward larger values of the temperature and lower values of the quark chemical potential, as compared to the case where the system can be regarded as completely thermalized. These effects may be important for relativistic heavy ion collisions, where the number of subsystems making up the whole interaction volume can be linked to the finite number of participants in the reaction.

scholarly journals CHIRALLY SYMMETRIC BUT CONFINED HADRONS AT FINITE DENSITY

2008 ◽  
Vol 23 (27n30) ◽  
pp. 2385-2388 ◽  
Author(s):  
L. YA. GLOZMAN ◽  
R. F. WAGENBRUNN
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Low Temperature ◽  
Quark Matter ◽  
Chemical Potential ◽  
Heavy Ion ◽  
Finite Density ◽  
Qcd Phase Diagram

At a critical finite chemical potential and low temperature QCD undergoes the chiral restoration phase transition. The folklore tradition is that simultaneously hadrons are deconfined and there appears the quark matter. We demonstrate that it is possible to have confined but chirally symmetric hadrons at a finite chemical potential and hence beyond the chiral restoration point at a finite chemical potential and low temperature there could exist a chirally symmetric matter consisting of chirally symmetric but confined hadrons. If it does happen in QCD, then the QCD phase diagram should be reconsidered with obvious implications for heavy ion programs and astrophysics.

scholarly journals STRONGLY INTERACTING MATTER AT FINITE CHEMICAL POTENTIAL: HYBRID MODEL APPROACH

2013 ◽  
Vol 28 (14) ◽  
pp. 1350051 ◽  
Author(s):  
P. K. SRIVASTAVA ◽  
C. P. SINGH
Keyword(s):  
Hybrid Model ◽  
Chemical Potential ◽  
Gluon Plasma ◽  
Model Description ◽  
Baryon Chemical Potential ◽  
Qcd Phase Diagram ◽  
Strongly Interacting ◽  
Hadron Gas ◽  
Quasiparticle Model ◽  
Model Approach

Search for a proper and realistic equation of state (EOS) for strongly interacting matter used in the study of the QCD phase diagram still appears as a challenging problem. Recently, we constructed a hybrid model description for the quark–gluon plasma (QGP) as well as hadron gas (HG) phases where we used an excluded volume model for HG and a thermodynamically consistent quasiparticle model for the QGP phase. The hybrid model suitably describes the recent lattice results of various thermodynamical as well as transport properties of the QCD matter at zero baryon chemical potential (μB). In this paper, we extend our investigations further in obtaining the properties of QCD matter at finite value of μB and compare our results with the most recent results of lattice QCD calculation.

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