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Yang Z. | Yang Y. | Yang L. | Yang H. X. | Yang Fan | Yang Yi | Yang Yang | Yang Y. X. | Yang J. | Yang H. J.

C David J. Fernández | C David J Fernández | C Susanth | c Aleksandar Ili\' | c Marko Kosti\' | c Stevan Pilipovi\' | C Jiji | C Swathi | C | C Dharmani Bhaveshkumar

B Krishna P | B | B Navaneethkrishnan | B A. M. Lopez | b A. Zepeda | B Arun I | b H. Salazar | B J. | B Krishna Bharadwaj | B M.

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Perturbation solutions of relativistic viscous hydrodynamics for longitudinally expanding fireballs

Jiang Ze-Fang, She Duan, Yang C. B., Hou Defu
26 Jan 2020 hep-th nucl-th arxiv.org/abs/2001.09416

The solutions of relativistic viscous hydrodynamics for longitudinal expanding fireballs is investigated with the Navier-Stokes theory and Israel-Stewart theory. The energy and Euler conservation equations for the viscous fluid are derived in Rindler coordinates with the longitudinal expansion effect is small. Under the perturbation assumption, an analytical perturbation solution for the Navier-Stokes approximation and numerical solutions for the Israel-Stewart approximation are presented. The temperature evolution with both shear viscous effect and longitudinal acceleration effect in the longitudinal expanding framework are presented and specifically temperature profile shows symmetry Gaussian shape in the Rindler coordinates. In addition, in the presence of the longitudinal acceleration expanding effect, the results of the Israel-Stewart approximation are compared to the results from Bjorken and Navier-Stokes approximation, and it gives a good description than the Navier-Stokes theories results at the early stages of evolution.

1+1 dimensional relativistic magnetohydrodynamics with longitudinal acceleration

She Duan, Jiang Ze Fang, Hou De-fu, Yang C. B.
02 Jul 2019 hep-ph nucl-th arxiv.org/abs/1907.01250

Non-central heavy-ion collisions generate the strongest magnetic field of the order of $10^{18}-10^{19}$ Gauss due to the electric current produced by the positively charged spectators that travel at nearly the speed of light. Such transient electromagnetic fields may induce various novel effects in the hydrodynamic description of the quark gluon plasma for non-central heavy-ion collisions. We investigate the longitudinal acceleration effects on the 1+1 dimensional relativistic magnetohydrodynamics with transverse magnetic fields. We analyze the proper time evolution of the system energy density. We find that the longitudinal acceleration parameter $\lambda^*$, magnetic field decay parameter $a$, equation of state $\kappa$, and initial magnetization $\sigma_0$ have nontrivial effects on the evolutions of the system energy density and temperature.

Pseudo-rapidity distribution from a perturbative solution of viscous hydrodynamics for heavy ion collisions at RHIC and LHC

Jiang Ze Fang, Yang C. B., Ding Chi, Wu Xiang-Yu
29 Aug 2018 nucl-th hep-ph hep-th arxiv.org/abs/1808.10287

The charged-particle's final state spectrum is derived from an analytic perturbative solution for the relativistic viscous hydrodynamics. By taking into account the longitudinal acceleration effect in relativistic viscous hydrodynamics, the pseudorapidity spectrum describes well the nucleus-nucleus colliding systems at RHIC and LHC. Based on both the extracted longitudinal acceleration parameters $\lambda^{}$ and a phenomenological description of the $\lambda^{}$, the charged-particle's pseudorapidity distributions for $\sqrt{s_{NN}}$ = 5.44 TeV Xe+Xe collisions are computed from the final state expression in a limited space-time rapidity $\eta_{s}$ region.

Measures of azimuthal correlations in relativistic heavy ion collisions

Li G. L., Yang C. B., Zhou D. M.
04 Sep 2017 nucl-th arxiv.org/abs/1709.01408

Based on the initial state geometrical symmetry for collisions between two identical heavy ions at high energy, the general form for the one- and two-particle azimuthal distributions is deduced. Relation between these distributions and the usual flow parameters is discussed. New measures for the azimuthal correlations are suggested. Some numerical results on the values of the measures are shown from an event generator for Au+Au collisions with different colliding centralities at 200 GeV.

Observable Properties of Quark-Hadron Phase Transition at the Large Hadron Collider

Hwa Rudolph C., Yang C. B.
18 Jan 2016 nucl-th hep-ph nucl-ex arxiv.org/abs/1601.04671

Quark-hadron phase transition is simulated by an event generator that incorporates the dynamical properties of contraction due to QCD confinement forces and randomization due to the thermal behavior of a large quark system on the edge of hadronization. Fluctuations of emitted pions in the $(\eta,\phi)$ space are analyzed using normalized factorial moments in a wide range of bin sizes. The scaling index $\nu$ is found to be very close to the predicted value in the Ginzburg-Landau formalism. The erraticity indices $\mu_q$ are determined in a number of ways that lead to the same consistent values. They are compared to the values from the Ising model, showing significant difference in a transparent plot. Experimental determination of $\nu$ and $\mu_q$ at the LHC are now needed to check the reality of the theoretical study and to provide guidance for improving the model description of quark-hadron phase transition.

Hadron formation from interaction among quarks

Tan Z. G., Yang C. B.
06 Oct 2014 hep-ph arxiv.org/abs/1410.1288

This paper deals with the hadronization process of quark system. A phenomenological potential is introduced to describe the interaction between a quark pair. The potential depends on the color charge of those quarks and their relative distances. Those quarks move according to classical equations of motion. Due to the color interaction, coloring quarks are separated to form color neutral clusters which are supposed to be the hadrons.

Scaling behavior of charged hadron $p_{T}$ distributions in $pp$ and $p\bar{p}$ collisions

Zhang W. C., Yang C. B.
20 Mar 2014 hep-ph arxiv.org/abs/1403.5347

We report on a scaling behaviour in the transverse momentum ($p_{T}$) distributions for charged hadrons produced in proton-proton ($pp$) collisions with different center of mass energies ($\sqrt{s}$ = 0.9, 2.76 and 7 TeV) at the Compact Muon Solenoid (CMS) detector. This scaling behaviour appears when the $p_{T}$ is replaced by $p_{T}/K$, where $K$ is a parameter and depends on $\sqrt{s}$. A similar scaling behaviour is observed in the $p_{T}$ distributions of charged hadrons produced in proton-antiproton ($p\bar{p}$) collisions with $\sqrt{s}$ = 0.63, 1.8 and 1.96 TeV at the Collider Detector at Fermilab (CDF). The particle production mechanism behind the scaling behaviour in the $pp$ or $p\bar{p}$ collisions could be explained by the model of percolation of strings.

Exact solution of rectangular Ising lattice in a uniform external field

Yang C. B.
26 Sep 2013 physics.gen-ph arxiv.org/abs/1310.0040

A method is proposed for exactly calculating the partition function of a rectangular Ising lattice with the presence of a uniform external field. This approach is based on the method of the transfer matrix developed about seventy years ago for the rectangular Ising model in the absence of external field. The basis for the vector space is chosen as the eigenvectors of the diagonal part of the transfer matrix. The matrix elements for the non-diagonal part can be calculated very easily. Then the partition function and thermodynamical quantities can be evaluated. The limit of infinite lattice is discussed.

On the Energy and Centrality Dependence of Higher Order Moments of Net-Proton Distributions in Relativistic Heavy Ion Collisions

Wang X., Yang C. B.
22 Feb 2012 nucl-th nucl-ex arxiv.org/abs/1202.4857

The higher order moments of the net-baryon distributions in relativistic heavy ion collisions are useful probes for the QCD critical point and fluctuations. Within a simple model we study the colliding energy and centrality dependence of the net-proton distributions in the central rapidity region. The model is based on considering the baryon stopping and pair production effects in the processes. Based on some physical reasoning, the dependence is parameterized. Predictions for the net-proton distributions for Au+Au and Pb+Pb collisions at different centralities at $\sqrt{s_{NN}}$=39 and 2760 GeV, respectively, are presented from the parameterizations for the model parameters. A possible test of our model is proposed from investigating the net proton distributions in the non-central rapidity region for different colliding centralities and energies.

Local Multiplicity Fluctuations as a Signature of Critical Hadronization at LHC

Hwa Rudolph C., Yang C. B.
28 Nov 2011 nucl-th hep-ph nucl-ex arxiv.org/abs/1111.6651

In central Pb-Pb collisions at LHC the multiplicity of particles produced is so high that it should become feasible to examine the nature of transition from the deconfined quark-gluon state to the confined hadron state by methods that rely on the availability of high multiplicity events. We consider four classes of the transition process ranging from critical behavior to totally random behavior, depending on whether or not there is clustering of quarks and on whether or not there is contraction of dense clusters due to confinement. Fluctuations of bin multiplicities in each event are quantified, and then the event-by-event fluctuations of spatial patterns are analyzed. A sequence of measures are proposed and are shown to be effective in capturing the essence of the differences among the classes of simulated events. It is demonstrated that a specific index has a low value for critical transition but a larger value if the hadronization process is random.