Maximizing the Azimuthal-Angle Correlation in the Decay of Vector Boson Pairs

TL;DR

This paper investigates the azimuthal-angle correlation in W boson pair decays, identifying the optimal basis for maximal spin correlation measurement, which aids in probing CP interactions and quantum information properties.

Contribution

It introduces a method to determine the optimal coordinate basis for maximizing azimuthal-angle spin correlations in W boson pairs, extending spin correlation studies.

Findings

Identified the basis dependence of azimuthal correlations.

Proposed the optimal coordinate direction for maximal correlation.

Applications to CP interaction measurements and quantum information.

Abstract

Spin correlation observables of particles produced at colliders generally depend on the coordinate basis. While spin correlations and their associated basis dependence have been studied in top-quark pair production, the basis dependence of spin correlations of a $W^\pm$ pair has not been studied. In this work, we focus on the azimuthal-angle correlation in the decay of a $W^\pm$ pair, which encodes spin information in the direction transverse to the rotational axis. We quantitatively describe the basis dependence of the relative azimuthal angle. We further present the optimal coordinate direction to define the azimuthal angle between the decay products of $W^\pm$ bosons to achieve the maximal spin correlation based on symmetry considerations. The results can be used to optimize the measurement of the CP-even and CP-odd interactions, and have applications to quantum information observables in the vector boson pair system.