Spin Correlations in Parton Shower Simulations

TL;DR

This paper demonstrates how to fully incorporate spin correlations into Herwig 7 Monte Carlo simulations across all stages and algorithms, improving the accuracy of event generation.

Contribution

It introduces the implementation of spin correlations in Herwig 7 for both angular-ordered and dipole showers, filling a key gap in simulation accuracy.

Findings

Spin correlations can be fully integrated into Herwig 7.

The implementation applies to all stages of event generation.

Enhanced simulation accuracy with spin effects included.

Abstract

Spin correlations are an important, but often neglected, effect in modern Monte Carlo event generators. We show that they can be fully incorporated in Herwig 7 using the algorithm originally proposed by Collins and Knowles in all stages of the event generation process and between the different stages of the event generation. In this paper we present the final missing ingredient, correlations in both the angular-ordered and dipole shower algorithms and between the parton shower and hard production and decay processes.