Breaking down the entire spectrum of spin correlations of a pair of particles involving fermions and gauge bosons

TL;DR

This paper develops a comprehensive formalism for analyzing spin correlations and polarizations in two-particle systems involving fermions and gauge bosons, with applications to standard model processes and anomalous couplings.

Contribution

It introduces a unified formalism linking spin correlations with angular distributions, and demonstrates its application to various particle collision processes, including effects of anomalous couplings.

Findings

Spin correlations can significantly improve sensitivity to anomalous couplings.

The formalism connects joint angular distributions with polarization and correlation observables.

Applications to standard model processes show the formalism's effectiveness.

Abstract

We discuss a formalism for the spin correlations and polarizations in two-particle systems with spins half-half, half-one and one-one, and provide the connections between the polarizations and correlations with the joint angular distributions of decay products identifying the asymmetries for them. We demonstrate the formalism in the processes $e^-e^+\to t\bar{t}$, $gb \to tW^-$ and $e^-e^+\to ZZ$ in the standard model as examples. We investigate the effect of some anomalous couplings on the polarizations and spin correlations in the processes $e^-e^+\to t\bar{t}$, $gb \to tW^-$ and $u\bar{d}\to ZW^+$ at parton level and compare their strengths. The spin correlations have the potential to provide a significant improvement over the polarizations in probing the anomalous couplings.