Four lepton production and the accuracy of QED FSR

TL;DR

This paper evaluates the accuracy of QED final-state resummation tools in predicting four-lepton production, comparing them with exact NLO electroweak calculations, and explores the effects of various analysis parameters.

Contribution

It provides a detailed validation of QED resummation methods against exact calculations and investigates parameter dependencies affecting precision.

Findings

Excellent agreement with fixed-order results

Partial differences at the few-percent level

Implications for precision measurements

Abstract

We scrutinise the ability of the primary QED final-state resummation tools, combined with electroweak virtual corrections, to reproduce the exact next-to-leading order electroweak calculation in the four-charged-lepton final state. We further examine the dependence of the findings on the lepton-photon dressing-cone size as well as the resonance identification strategy. Overall we find excellent agreement with the fixed-order result, but partial differences not directly connected with resummation-induced higher-order effects at the few-percent level are observed in some cases, which are relevant for precision measurements.