Probing quark gluon plasma properties by heavy flavours

TL;DR

This paper uses the Fokker Planck equation to analyze heavy quark interactions in quark-gluon plasma, comparing theoretical spectra with experimental data to understand plasma properties and the role of equilibrium states.

Contribution

It introduces a formalism combining the Fokker Planck equation with fragmentation functions to study heavy flavor spectra in QGP, highlighting the importance of non-equilibrium effects and the equation of state.

Findings

Experimental data cannot distinguish equilibrium from non-equilibrium charm spectra.

Enhanced pQCD cross sections can reproduce non-photonic electron suppression data.

Ideal gas equation of state does not fit the data even with cross section enhancement.

Abstract

The Fokker Planck (FP) equation has been solved to study the interaction of non-equilibrated heavy quarks with the Quark Gluon Plasma (QGP) expected to be formed in heavy ion collisions at RHIC energies. The solutions of the FP equation have been convoluted with the relevant fragmentation functions to obtain the $D$ and $B$ meson spectra. The results are compared with experimental data measured by STAR collaboration. It is found that the present experimental data can not distinguish between the $p_T$ spectra obtained from the equilibrium and non-equilibrium charm distributions. Data at lower $p_T$ may play a crucial role in making the distinction between the two. The nuclear suppression factor, $R_{\mathrm AA}$ for non-photonic single electron spectra resulting from the semileptonic decays of hadrons containing heavy flavours have been evaluated using the present formalism. It is observed that the experimental data on nuclear suppression factor of the non-photonic electrons can be reproduced within this formalism by enhancing the pQCD cross sections by a factor of 2 provided the expansion of the bulk matter is governed by the velocity of sound, $c_s\sim 1/\sqrt{4}$. Ideal gas equation of state fails to reproduce the data even with the enhancement of the pQCD cross sections by a factor of 2.