Drag induced radiation and multi-stage effects in heavy-flavor energy loss

S Cao,A Majumder,G.-Y Qin,C Shen

doi:10.1016/j.physletb.2019.05.020

S Cao, A Majumder + Show 2 more

Open Access

https://doi.org/10.1016/j.physletb.2019.05.020

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Abstract

It is argued that heavy-quarks traversing a Quark Gluon Plasma, undergo a multi-stage modification process, similar to the case of light flavors. Such an approach is applied to heavy-quark energy loss, which includes a rare-scattering, multiple emission formalism at momenta large compared to the mass (sensitive only to the transverse diffusion coefficient qˆ), and a single scattering induced emission formalism (Gunion-Bertsch) at momenta comparable to the mass of the quark [sensitive to qˆ, and the longitudinal drag (eˆ) and diffusion (eˆ2) coefficients]. The application of such a multi-stage approach within a 2+1D viscous fluid-dynamical simulation leads to simultaneous agreement with experimental data for the nuclear modification factor of both B and D mesons, as measured by the CMS collaboration at the LHC. The extracted transport coefficients are found to be consistent with those for light flavors.

Highlights

The logarithmic dependence of the QCD coupling constant [αS (Q2)] on the scale of the process (Q2) ensures that phenomena that depend on strong interactions change dramatically as the scale changes by an order of magnitude [1, 2]
In this Letter, we will demonstrate that a multi-stage energy loss formalism along with new mass dependent additive components to radiative loss that depend on the drag and longitudinal diffusion coefficients (e, e2), are sufficient to explain the additional suppression seen in the heavy-flavor sector
We have presented the first implementation of a multi-stage formalism to heavy-quark energy loss

Summary

Introduction

The logarithmic dependence of the QCD coupling constant [αS (Q2)] on the scale of the process (Q2) ensures that phenomena that depend on strong interactions change dramatically as the scale changes by an order of magnitude [1, 2]. For cases where the resulting remnant momentum of the heavy-quark is comparable to the mass of the heavy-quark, it undergoes further energy loss via a Gunion-Bertsch [19] type of process, where scatterings off the medium trigger radiation from the heavy-quark Such a stage is to be distinguished from the traditional picture of multiple scattering induced radiation for massless flavors, which requires several scatterings per emission, and is denoted as the Baier-Dokshitzer-Mueller-Peigne-Schiff (BDMPS) approach [20, 21, 22, 23, 24].

Semi-hard heavy-quarks

The case of massless flavors

The case of massive flavors

Nuclear modification factor for D and B mesons

Discussions and conclusions