Dynamical resolution scale in transverse momentum distributions at the LHC

TL;DR

This paper explores the impact of dynamical, branching scale dependent resolution scales on the evolution of transverse momentum distributions in QCD, providing analytical and numerical insights relevant for LHC Z-boson production predictions.

Contribution

It introduces and analyzes the effects of dynamical resolution scales within the parton branching formalism for TMD evolution, advancing understanding of soft-gluon coherence effects.

Findings

Dynamical resolution scales influence TMD evolution significantly.

Comparison shows differences between PB approach and other models.

Predictions for Z-boson transverse momentum distributions are refined.

Abstract

The QCD evolution of transverse momentum dependent (TMD) distribution functions has recently been formulated in a parton branching (PB) formalism. In this approach, soft-gluon coherence effects are taken into account by introducing the soft-gluon resolution scale and exploiting the relation between transverse-momentum recoils and branching scales. In this work we investigate the implications of dynamical, i.e., branching scale dependent, resolution scales. We present both analytical studies and numerical solution of PB evolution equations in the presence of dynamical resolution scales. We use this to compare PB results with other approaches in the literature, and to analyze predictions for transverse momentum distributions in $Z$-boson production at the Large Hadron Collider (LHC).