Optimal spin-quantization axes for the polarization of dileptons with large transverse momentum

TL;DR

This paper proposes optimal spin-quantization axes for dilepton polarization at large transverse momentum, improving the rate of polarization approach by considering dilepton momentum and jet direction.

Contribution

It introduces a method to select axes that optimize the polarization rate for dileptons produced with high transverse momentum.

Findings

Optimal axes depend on dilepton momentum and jet direction.

The proposed axes improve polarization measurement accuracy.

Transverse polarization increases with transverse momentum.

Abstract

The leading-order parton processes that produce a dilepton with large transverse momentum predict that the transverse polarization should increase with the transverse momentum for almost any choice of the quantization axis for the spin of the virtual photon. The rate of approach to complete transverse polarization depends on the choice of spin quantization axis. We propose axes that optimize that rate of approach. They are determined by the momentum of the dilepton and the direction of the jet that provides most of the balancing transverse momentum.