Dynamics of QCD matter — current status

Abstract

In this article, there are 18 sections discussing various current topics in the field of relativistic heavy-ion collisions and related phenomena, which will serve as a snapshot of the current state of the art. Section 1 reviews experimental results of some recent light-flavored particle production data from ALICE collaboration. Other sections are mostly theoretical in nature. Very strong but transient magnetic field created in relativistic heavy-ion collisions could have important observational consequences. This has generated a lot of theoretical activity in the last decade. Sections 2, 7, 9, 10 and 11 deal with the effects of the magnetic field on the properties of the QCD matter. More specifically, Sec. 2 discusses mass of [Formula: see text] in the linear sigma model coupled to quarks at zero temperature. In Sec. 7, one-loop calculation of the anisotropic pressure are discussed in the presence of strong magnetic field. In Sec. 9, chiral transition and chiral susceptibility in the NJL model is discussed for a chirally imbalanced plasma in the presence of magnetic field using a Wigner function approach. Sections 10 discusses electrical conductivity and Hall conductivity of hot and dense hadron gas within Boltzmann approach and Sec. 11 deals with electrical resistivity of quark matter in presence of magnetic field. There are several unanswered questions about the QCD phase diagram. Sections 3, 11 and 18 discuss various aspects of the QCD phase diagram and phase transitions. Recent years have witnessed interesting developments in foundational aspects of hydrodynamics and their application to heavy-ion collisions. Sections 12 and 15–17 of this article probe some aspects of this exciting field. In Sec. 12, analytical solutions of viscous Landau hydrodynamics in 1+1D are discussed. Section 15 deals with derivation of hydrodynamics from effective covariant kinetic theory. Sections 16 and 17 discuss hydrodynamics with spin and analytical hydrodynamic attractors, respectively. Transport coefficients together with their temperature- and density-dependence are essential inputs in hydrodynamical calculations. Sections 5, 8 and 14 deal with calculation/estimation of various transport coefficients (shear and bulk viscosity, thermal conductivity, relaxation times, etc.) of quark matter and hadronic matter. Sections 4, 6 and 13 deal with interesting new developments in the field. Section 4 discusses color dipole gluon distribution function at small transverse momentum in the form of a series of Bells polynomials. Section 6 discusses the properties of Higgs boson in the quark–gluon plasma using Higgs–quark interaction and calculate the Higgs decays into quark and anti-quark, which shows a dominant on-shell contribution in the bottom-quark channel. Section 13 discusses modification of coalescence model to incorporate viscous corrections and application of this model to study hadron production from a dissipative quark–gluon plasma.

Thermal Freeze-Out Parameters and Pseudoentropy from Charged Hadron Spectra in High-Energy Collisions

“…We now discuss this topic further. As we know, high-energy collisions contain abundant information which are related to the productions of QGP and particles [55][56][57][58][59][60][61][62]. Of course, after a very short time, QGP finally decays into particles.…”

Extended relaxation time approximation and relativistic dissipative hydrodynamics

“…This is not surprising because for large mass, a = ±1 in Eqs. ( 6) and (24), which is relevant for quantum statistics, can be ignored and hence the thermodynamics is dominated by classical physics. Therefore the large mass limit is both nonrelativistic and classical limit.…”

“…Regardless of its simplistic nature, the RTA turns out to be very useful and has been employed quite extensively to formulate relativistic dissipative hydrodynamics and derive the form of transport coefficients [5,[11][12][13][14][15][16]. Recently, it has also been employed to study the domain of applicability of hydrodynamics and study the hydrodynamization phenomena [17][18][19][20][21][22][23][24][25][26][27]. This simple model seems to capture the effective microscopic interaction for a wide range of theories.…”

Thermal freeze-out parameters and pseudo-entropy from charged hadron spectra in high energy collisions

“…We now discuss this topic further. As we know, high energy collisions contain abundant information which are related to the productions of QGP and particles [70][71][72][73][74][75][76][77]. Of course, after a very short time, QGP finally decays into particles.…”