Explanation of Di-jet asymmetry in Pb+Pb collisions at the Large Hadron Collider

TL;DR

This paper models the evolution of jet showers in quark-gluon plasma to explain di-jet asymmetry observed in Pb+Pb collisions at the LHC, highlighting the roles of medium effects on radiation and energy loss.

Contribution

It introduces a differential equation approach to describe jet energy loss and medium modifications, providing a detailed theoretical framework for di-jet asymmetry.

Findings

Jet energy loss is dominated by medium effects on vacuum radiation early on.

Medium-induced radiation significantly contributes to energy loss at later times.

Numerical results align with ATLAS experimental data on di-jet asymmetry.

Abstract

We investigate the medium modification of a partonic jet shower traversing in a hot quark-gluon plasma. We derive and solve a differential equation that governs the evolution of the radiated gluon spectrum as the jet propagates through the medium. Energy contained inside the jet cone is lost by dissipation through elastic collisions with the medium and by scattering of shower partons to larger angles. We find that the jet energy loss at early times is dominated by medium effects on the vacuum radiation, and by medium-induced radiation effects at late times. We compare our numerical results for the nuclear modification of the di-jet asymmetry with that recently reported by the ATLAS collaboration.