Surasree Mazumder

Momentum dependence of drag coefficients and heavy flavour suppression in quark gluon plasma

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

Examination of the Gunion-Bertsch formula for soft gluon radiation

D^0

Gluon bremsstrahlung by heavy quarks: Its effects on transport coefficients and equilibrium distribution

in Pb+Pb collisions at LHC energy - recently measured by the ALICE collaboration has also been studied.

Heavy quark diffusion in the pre-equilibrium stage of heavy ion collisions

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.

Effects of equation of state on nuclear suppression and the initial entropy density of quark gluon plasma

The effects of gluon radiation by charm quarks on the transport coefficients {\it 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.

Gluon Radiation Off Heavy Flavour Jets

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 relativistic heavy ion collider and Large Hadron Collider energies. 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 quantum chromodynamics. 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 HQ 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.

A random walk with heavy flavours

We study the effects of the equation of state on the nuclear suppression of heavy flavours in quark gluon plasma and estimate the initial entropy density of the system produced at the highest RHIC energy. For this purpose we have used the experimental data on the charged particle multiplicity and the nuclear suppression of single electron spectra originating from the semi-leptonic decays of open charm and beauty mesons. We have used inputs from lattice QCD to minimize the model dependence of the results. We obtain the value of the initial entropy density which varies from 20 to 59 /fm

Gluon radiation off heavy quarks in large angle scattering

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Effect of Gluon Radiation Off Charm Quark on Transport Coefficients and the Equilibrium Distribution of Charm Quark

depending on the value of the velocity of sound that one uses for the analysis. Our investigation leads to a conservative value of the initial entropy density

Radiative Processes in Quark-Gluon Plasma

\sim 20/