Automated evaluation of electroweak Sudakov logarithms in SHERPA

Enrico Bothmann,Davide Napoletano

doi:10.1140/epjc/s10052-020-08596-2

Abstract

We present an automated implementation for the calculation of one-loop double and single Sudakov logarithms stemming from electroweak radiative corrections within the SHERPA event generation framework, based on the derivation in Denner and Pozzorini (Eur Phys J C 18:461–480, 2001). At high energies, these logarithms constitute the leading contributions to the full NLO electroweak corrections. As examples, we show applications for relevant processes at both the LHC and future hadron colliders, namely on-shell W boson pair production, EW-induced dijet production and electron–positron production in association with four jets, providing the first estimate of EW corrections at this multiplicity.

Highlights

In perturbative electroweak (EW) theory, higher-order corrections include, among other contributions, emissions of virtual and real gauge bosons and are known to have a large effect in the hard tail of observables at the LHC and future colliders [2]
The aim is twofold, first we wish to show the variety of processes that can be computed with our implementation, and second we want to compare to existing alternative methods to obtain EW corrections to further study the quality of the approximation
We focus on the discussion of transverse momentum distributions, since they are directly sensitive to the growing effect of the logarithmic contributions when approaching the high-energy limit

Summary

Introduction

In perturbative electroweak (EW) theory, higher-order corrections include, among other contributions, emissions of virtual and real gauge bosons and are known to have a large effect in the hard tail of observables at the LHC and future colliders [2]. [21,22]), the full set of NLO EW corrections for complicated final states may not be available yet or might not be numerically tractable due to the calculational complexity for a given application Another obstacle for the application of NLO EW corrections is the missing automation of the matching to electromagnetic (let alone EW) showers needed for particle-level event generation, some process-specific matching implementations exist, e.g. Drell–Yan production [21,23,24]. Compared to the Sudakov EW corrections used as an approximation of the virtual NLO EW, the EWvirt scheme differs due to the inclusion of exact virtual corrections and integrated subtraction terms These differences are either subleading or constant at high energy in the logarithmic counting, but they can lead to numerically sizeable effects, depending on the process, the observable and the applied cuts.

SHERPA implementation

Results

W W production in pp collisions at 13 and 100 TeV

EW-induced dijet production in pp collisions at 13 TeV

Off-shell Z production in association with 4 jets in pp collisions at 13 TeV

Conclusions