Angular correlations in multi-jet final states from kt-dependent parton showers

TL;DR

This paper explores how transverse-momentum dependent parton showers can better model angular correlations in multi-jet events at high-energy colliders, revealing effects not captured by standard methods.

Contribution

It introduces TMD-based parton-branching methods that incorporate QCD coherence effects in space-like branching, improving simulation accuracy for multi-jet final states.

Findings

TMD showers better reproduce angular correlations in multi-jet events.

Finite-angle gluon radiation effects are significant for accurate modeling.

Comparisons show improved agreement with experimental data.

Abstract

We investigate parton-branching methods based on transverse-momentum dependent (TMD) parton distributions and matrix elements for the Monte Carlo simulation of multi-particle final states at high-energy colliders. We observe that recently measured angular correlations in ep final states with multiple hadronic jets probe QCD coherence effects in the space-like branching, associated with finite-angle gluon radiation from partons carrying small longitudinal momenta, and not included in standard shower generators. We present Monte Carlo calculations for azimuthal two-jet and three-jet distributions, for jet multiplicities and for correlations in the transverse-momentum imbalance between the leading jets. We discuss comparisons with current experimental multi-jet data, and implications of corrections to collinear-ordered showers for LHC final states.