Spin correlations in final-state parton showers and jet observables

TL;DR

This paper develops and implements a method to include spin correlations in parton shower simulations, enabling more accurate modeling of jet observables and quantum effects in high-energy physics.

Contribution

It adapts the Collins-Knowles algorithm to PanScales showers and introduces new observables for validating spin correlation effects in jet physics.

Findings

Successful implementation of spin correlations in PanScales showers

Development of Lund-declustering observables sensitive to spin effects

Extension of MicroJets code for spin-aware resummation

Abstract

As part of a programme to develop parton showers with controlled logarithmic accuracy, we consider the question of collinear spin correlations within the PanScales family of parton showers. We adapt the well-known Collins-Knowles spin-correlation algorithm to PanScales antenna and dipole showers, using an approach with similarities to that taken by Richardson and Webster. To study the impact of spin correlations, we develop Lund-declustering based observables that are sensitive to spin-correlation effects both within and between jets and extend the MicroJets collinear single-logarithmic resummation code to include spin correlations. Together with a 3-point energy correlation observable proposed recently by Chen, Moult and Zhu, this provides a powerful set of constraints for validating the logarithmic accuracy of our shower results. The new observables and their resummation further open the pathway to phenomenological studies of these important quantum mechanical effects.