Calculating the primary Lund Jet Plane density

TL;DR

This paper presents a comprehensive all-order calculation of the primary Lund-jet plane density in QCD, including various effects and matching to NLO, with phenomenological estimates and comparison to ATLAS data showing good agreement.

Contribution

It provides the first all-order single logarithmic calculation of the primary Lund-plane density, incorporating running coupling, collinear, and soft effects, and compares with experimental data.

Findings

Achieves 5-7% precision at high transverse momenta

Worsens to 20% precision at lower momenta (~5 GeV)

Shows good agreement with ATLAS measurements

Abstract

The Lund-jet plane has recently been proposed as a powerful jet substructure tool with a broad range of applications. In this paper, we provide an all-order single logarithmic calculation of the primary Lund-plane density in Quantum Chromodynamics, including contributions from the running of the coupling, collinear effects for the leading parton, and soft logarithms that account for large-angle and clustering effects. We also identify a new source of clustering logarithms close to the boundary of the jet, deferring their resummation to future work. We then match our all-order results to exact next-to-leading order predictions. For phenomenological applications, we supplement our perturbative calculation with a Monte Carlo estimate of non-perturbative corrections. The precision of our final predictions for the Lund-plane density is 5-7% at high transverse momenta, worsening to about 20% at the lower edge of the perturbative region, corresponding to transverse momenta of about 5 GeV. We compare our results to a recent measurement by the ATLAS collaboration at the Large-Hadron Collider, revealing good agreement across the perturbative domain, i.e. down to about 5 GeV.