Gluon Bremsstrahlung in Weakly-Coupled Plasmas

TL;DR

This paper discusses theoretical advances in calculating gluon bremsstrahlung in weakly-coupled quark-gluon plasmas, including formalism equivalences, expansion techniques, and perturbative estimates of transport coefficients.

Contribution

It demonstrates the equivalence of two major formalisms, explores the validity of logarithmic expansions, and provides perturbative calculations of the transport coefficient $\

Findings

BDMPS-Zakharov and AMY formalisms can be made equivalent.

Logarithmic expansions are effective for $\\omega/T \\gtrsim 10$.

Perturbative calculations of $\

Abstract

I report on some theoretical progress concerning the calculation of gluon bremsstrahlung for very high energy particles crossing a weakly-coupled quark-gluon plasma. (i) I advertise that two of the several formalisms used to study this problem, the BDMPS-Zakharov formalism and the AMY formalism (the latter used only for infinite, uniform media), can be made equivalent when appropriately formulated. (ii) A standard technique to simplify calculations is to expand in inverse powers of logarithms $\ln(E/T)$. I give an example where such expansions are found to work well for $\omega/T \gtrsim 10$ where $\omega$ is the bremsstrahlung gluon energy. (iii) Finally, I report on perturbative calculations of $\hat q$.