Dilepton Helical Production in a Vortical Quark-Gluon Plasma

TL;DR

This paper introduces a new observable called the dilepton helical rate, which measures the difference in helicity states of lepton pairs in a vortical quark-gluon plasma, serving as a potential tool to gauge plasma vorticity.

Contribution

It derives the dilepton helical rate in a vortical quark-gluon plasma and proposes its use as a novel vortical-meter for such plasmas.

Findings

Helical rate maximizes when the auxiliary vector aligns with vorticity.

The helical rate distribution is nearly spherical oblate.

The proposed observable can serve as a vortical-meter.

Abstract

In this paper, we propose an observable counting a weighted difference between right-handed and left-handed lepton pairs, which is coined dilepton helical rate. The weight is the momentum difference of the lepton pairs projected onto an auxiliary vector. We derive the helical rate in a quark-gluon plasma with a vorticity in the limit when the quark and lepton masses are ignored. We find the helical rate is maximized when the auxiliary vector is parallel to the vorticity, in which case it has a nearly spherical oblate ellipsoidal distribution. We propose that it can be used as a vortical-meter for quark-gluon plasma.