Mahatsab Mandal — Page 2

arXiv2012

Collective modes of an anisotropic quark-gluon plasma induced by relativistic jets

We discuss the characteristics of collective modes induced by relativistic jets in an anisotropic quark-gluon plasma(AQGP). Assuming a tsunami-like initial jet distribution, it is found that the dispersion relations for both the stable and unstable modes are modified substantially due to the passage of jet compared to the case when there is no jet. It has also been shown that the growth rate of instability first increases compared to the no jet case and then completely turned into damping except the case when the jet velocity is perpendicular to the wave vector in which case the instability always grows. Thus, the introduction of the jet in the AQGP, in general, might to faster isotropization for the special case when the wave vector is parallel to the anisotropy axis.

hep-ph↗

arXiv2011

Nuclear modification factor in an anisotropic {\em Quark-Gluon-Plasma}

We calculate the nuclear modification factor ($R_{AA}$) of light hadrons by taking into account the initial state momentum anisotropy of the quark gluon plasma (QGP) expected to be formed in relativistic heavy ion collisions. Such an anisotropy can result from the initial rapid longitudinal expansion of the matter. A phenomenological model for the space time evolution of the anisotropic QGP is used to obtain the time dependence of the anisotropy parameter $ξ$ and the hard momentum scale, $p_{\rm hard}$. The result is then compared with the PHENIX experimental data to constrain the isotropization time scale, $τ_{\rm iso}$ for fixed initial conditions (FIC). It is shown that the extracted value of $τ_{\rm iso}$ lies in the range $0.5 \leq τ_{\rm iso} \leq 1.5$. However, using fixed final multiplicity (FFM) condition does not lead to any firm conclusion about the extraction of the isotropization time. The present calculation is also extended to contrast with the recent measurement of nuclear modification factor by ALICE collaboration at $\sqrt{s}=2.76$ TeV. It is argued that in the present approach, the extraction of $τ_{\rm iso}$ at this energy is uncertain and, therfore, refinement of the model is necessary. The sensitivity of the results on the initial conditions has been discussed. We also present the nuclear modification factor at LHC energies with $\sqrt{s} = 5.5$ TeV.

hep-ph↗

arXiv2011

Energy loss due to field fluctuations in a two-stream QCD plasma

We derive the expression for the collisional energy loss in two stream plasma induced by the fluctuating chromoelectric field. It is revealed that the main contribution here comes from the unstable modes which grow exponentially with time. A strong direction dependence of the energy loss has also been demonstrated.

hep-ph↗