Toward a solution to the R and v2 puzzle for heavy quarks

Abstract

The two key observables related to heavy quarks that have been measured in RHIC and LHC energies are the nuclear suppression factor RAA and the elliptic flow v2. Simultaneous description of these two observables is a top challenge for all the existing models. We have highlighted how a consistent combination of four ingredients i.e the temperature dependence of the energy loss, full solution of the Boltzmann collision integral for the momentum evolution of heavy quark, hadronization by coalescence, then the hadronic rescattering, responsible to address a large part of such a puzzle. We have considered four different models to evaluate the temperature dependence of drag coefficients of the heavy quark in QGP. All these four different models are set to reproduce the same RAA as of the experiments. We have shown that for the same RAA, the v2 could be quite different depending on the interaction dynamics as well as other ingredients.

Energy loss, hadronization, and hadronic interactions of heavy flavors in relativistic heavy-ion collisions

“…It has been suggested that heavy quarks produced by the gluon splitting process may experience different medium modification pattern compared to those directly produced through the hard scatterings [77]. As discussed earlier, by increasing the relative contribution of energy loss near T c , the heavy quark v 2 may be increased a lot without affecting its overall suppression [73,74]; this might be helpful to explain the large v 2 puzzle. These aspects will be explored in our future work.…”

“…For instance, it has been suggested in Refs. [73,74] that by taking into account the temperature dependence of the transport coefficient (q/T 3 ) and increasing the relative contribution of the medium modification to heavy flavor spectra around T c , the anisotropy parameter v 2 in the final state can be effectively enhanced. These effects will be investigated in detail in the future.…”

Impact of momentum space anisotropy on heavy quark dynamics in a QGP medium

“…Note that while obtaining effective Vlasov-Dupree equation in Eq. (18). The operator L 2 is defined as:…”

“…To address this, one requires to describe the dynamics of the HQs propagating through the QGP. Therefore, one can explore the physics of the HQ transport [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] in the QGP medium as follows.The non-equilibrated HQs can travel in the equilibrated QGP medium, and one has to deal the problem within the framework of Langevin dynamics [22]. This is to say that the HQs perform random motion in the equilibrated QGP.…”

Heavy quark dynamics in the QGP: Towards a solution of theRAAandν2puzzle

“…However all the approaches show some difficulties to describe both the nuclear modification factor and the elliptic flow simultaneously. To study the time evolution of R AA and v 2 we have solved the Fokker Planck (FP) equation stochastically in terms of the Langevin equation, for detail we refer to our previous work [11]. The evolution of the bulk is provided by a 3+1D relativistic transport code tuned at fixed η/s [18] which is able to reproduce the same results of hydrodynamical simulations.…”