The momentum dependence of the drag coefficient of heavy quarks propagating through quark gluon plasma (QGP) has been evaluated. The results have been used to estimate the nuclear suppression factor of charm and bottom quarks in QGP. We observe that the momentum dependence of the transport coefficients plays crucial role in the suppression of the heavy quarks and consequently in discerning the properties of QGP using heavy flavours as a probe. We show that the large suppression of the heavy quarks observed at RHIC and LHC is predominantly due to the radiative losses. The suppression of D 0 in Pb+Pb collisions at LHC energy -recently measured by the ALICE collaboration has also been studied.
Abstract. The drag and diffusion coefficients of heavy quarks (HQs) have been evaluated in the pre-equilibrium phase of the evolving fireball produced in heavy ion collisions at RHIC and LHC energies. The KLN and classical Yang-Mills spectra have been used for describing the momentum distributions of the gluons produced just after the collisions but before they thermalize. The interaction of the HQs with these gluons has been treated within the framework of perturbative QCD. We have observed that the HQs are dragged almost equally by the kinetically equilibrated and out-of-equilibrium gluonic systems. We have also noticed that the HQs diffusion in the pre-equilibrium gluonic phase is as fast as in the kinetically equilibrated gluons. Moreover, the diffusion is faster in the pre-equilibrium phase than in the chemically equilibrated quark-gluon plasma. These findings may have significant impact on the analysis of experimental results on the elliptic flow and the high momentum suppression of the open charm and beauty hadrons.
The effects of gluon radiation by charm quarks on the transport coefficients e.g. drag, longitudinal and transverse diffusion and shear viscosity have been studied within the ambit of perturbative quantum chromodynamics (pQCD) and kinetic theory. We found that while the soft gluon radiation has substantial effects on the transport coefficients of the charm quarks in the quark gluon plasma its effects on the equilibrium distribution function is insignificant.
The spectrum of emitted gluons from the process g+g -> g+g+g has been
evaluated by relaxing some of the approximations used in earlier works. The
difference in the results from earlier calculations have been pointed out. The
formula obtained in the present work has been applied to estimate physical
quantities like equilibration rate of gluons and the energy loss of fast gluon
in the gluonic plasma.Comment: One LaTeX file for the text and three eps files for figure
We study the effect of the magnetic field on the collisional energy loss of heavy quark (HQ) moving in a magnetized thermal partonic medium. This is investigated in the strong field approximation where the lowest Landau level (LLL) becomes relevant. We work in the limit g √ eB T √ eB which is relevant for heavy ion collisions. Effects of the magnetic field are incorporated through the resummed gluon propagator in which the dominant contribution arises from the quark loop. We also take the approximation √ eB M , M being the HQ mass, so that the HQ is not Landau quantized. It turns out that there are only two types of scatterings that contribute to the energy loss of HQ; the Coulomb scattering of HQ with light quarks/anti-quarks and the t-channel Compton scattering. It is observed that for a given magnetic field, the dominant contribution to the collisional energy loss arises from Compton scattering process i.e., Qg → Qg. On the other hand, of the two processes, the Coulomb scattering i.e., Qq → Qq is more sensitive to the magnetic field. The net collisional energy loss is seen to increase with increase in the magnetic field. For a reasonable strength of the magnetic field, the field dependent contribution to the collisional energy loss is of the same order as to the case without magnetic field which can be important for the jet quenching phenomena in the heavy ion collision experiments.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.