Heavy quark diffusion and radiation at intermediate momentum

TL;DR

This paper investigates heavy quark diffusion and radiation at intermediate momenta, highlighting the importance of finite mass effects, and combines theoretical models with lattice QCD data to analyze nuclear suppression patterns.

Contribution

It introduces a combined approach to model heavy quark energy loss, incorporating both diffusion and radiative processes with finite mass effects at intermediate momentum.

Findings

Heavy quark distribution depends on the dominant energy loss mechanism.

Transition from diffusion-dominated to radiation-dominated suppression with increasing momentum.

Radiative effects are significant at intermediate momenta depending on model parameters.

Abstract

We discuss heavy quark diffusion and radiation in an intermediate-momentum regime where finite mass effects can be significant. Diffusion processes are described in the Fokker-Planck approximation for soft momentum transfer, while radiative ones are taken into account by nearly collinear gluon emission from a single scattering in the Boltzmann equation. We also consider radiative corrections to the transverse momentum diffusion coefficient, which are $\mathcal{O}(g^2)$ suppressed than the leading-order diffusion coefficient but logarithmically enhanced. Numerical results show that the heavy quark distribution function depends on the energy loss mechanism so that the momentum dependence of suppression is distinguishable. Employing the heavy quark diffusion coefficient constrained by lattice QCD data, we estimate the nuclear modification factor which exhibits a transition from diffusion at low momentum to radiation at high momentum. The significance of radiative effects at intermediate momentum depends on the diffusion coefficient and running coupling constant.