Papers by santosh kumar Das
Physics Letters B, 2019
In the pre-thermal equilibrium stage of relativistic heavy-ion collisions, a strong quasi-classic... more In the pre-thermal equilibrium stage of relativistic heavy-ion collisions, a strong quasi-classical transverse gluon field emerges at about τ0 ≃ 0.1 fm/c and evolves together with their longitudinal counterparts according to the classical Yang-Mills (CYM) equations. Recently it has been shown that these fields induce a diffusion of charm quarks in momentum space resulting in a tilt of their spectrum without a significant drag. We find that in nucleus-nucleus collisions at LHC such a novel dynamics of charm quarks leads to an initial enhancement of the nuclear modification factor (RAA) at pT larger than 2 GeV/c contrary to the standard lore. Moreover, the same dynamics leads to a larger final elliptic flow (v2) inducing a relation between RAA and v2 that is quite close to the experimental measurements. Our study also shows that such an initial pre-thermal stage is unlikely to be described in terms of a standard drag and diffusion dynamics, because even if one tune such coefficients to reproduce the same RAA(pT) this would imply a significantly smaller v2.
Nuclear and Particle Physics Proceedings, 2016
One of the primary aims of the ongoing nuclear collisions at Relativistic Heavy Ion Collider (RHI... more One of the primary aims of the ongoing nuclear collisions at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) energies is to create a Quark Gluon Plasma (QGP). The heavy quarks constitutes a unique probe of the QGP properties. Both at RHIC and LHC energies a puzzling relation between the nuclear modification factor R AA (p T) and the elliptic flow v 2 (p T) related to heavy quark has been observed which challenged all the existing models. We discuss how the temperature dependence of the heavy quark drag coefficient can address for a large part of such a puzzle. We have considered four different models to evaluate the temperature dependence of drag and diffusion coefficients propagating through a quark gluon plasma (QGP). All the four different models are set to reproduce the same R AA (p T) experimentally observed at RHIC energy. We have found that for the same R AA (p T) one can generate 2 − 3 times more v 2 depending on the temperature dependence of the heavy quark drag coefficient.
The heavy quarks constitutes a unique probe of the quark-gluon plasma properties. Both at RHIC an... more The heavy quarks constitutes a unique probe of the quark-gluon plasma properties. Both at RHIC and LHC energies a puzzling relation between the nuclear modification factor $R_{AA}(p_T)$ and the elliptic flow $v_2(p_T)$ has been observed which challenged all the existing models, especially for D mesons. We discuss how the temperature dependence of the heavy quark drag coefficient is responsible to address for a large part of such a puzzle. In particular, we have considered four different models to evaluate the temperature dependence of drag and diffusion coefficients propagating through a quark gluon plasma (QGP). All the four different models are set to reproduce the same $R_{AA}(p_T)$ observed in experiments at RHIC and LHC energy. We point out that for the same $R_{AA}(p_T)$ one can generate 2-3 times more $v_2$ depending on the temperature dependence of the heavy quark drag coefficient. An increasing drag coefficient as $ T \rightarrow\ T_c \,$ is a major ingredient for a simulta...
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Papers by santosh kumar Das