Accurate simulation of W, Z, and Higgs boson decays in Sherpa

Frank Krauss,Robin Linten,Jonas M Lindert,Marek Schönherr

doi:10.1140/epjc/s10052-019-6614-x

Abstract

We discuss the inclusion of next-to–next-to leading order electromagnetic and of next-to leading order electroweak corrections to the leptonic decays of weak gauge and Higgs bosons in the Sherpa event generator. To this end, we modify the Yennie– Frautschi–Suura scheme for the resummation of soft photon corrections and its systematic improvement with fixed-order calculations, to also include the effect of virtual corrections due to the exchange of weak gauge bosons. We detail relevant technical aspects of our implementation and present numerical results for observables relevant for high-precision Drell–Yan and Higgs boson production and decay simulations at the LHC.

Highlights

The demand forpercent precision in Drell–Yan production has led to formidable achievements in the theoretical description of corresponding collider observables, often pushing boundaries of technical limitations
We will primarily be concerned with this correction factor, in particular with the virtual corrections at next-to-leading order (NLO), the term β01, which we extend to an expression at full NLO in the electroweak theory for the decays of the weak bosons, as well as the complete next-to–next-to-leading order (NNLO) bracket which we will be calculating for the neutral weak bosons;
We present the numerical effects induced by the NLO EW and NNLO QED corrections presented in the previous section, focussing on the decays Z → + −, W → ν and H → + − with = {e, μ, τ } following hadronic neutral-current and charged-current Drell–Yan and Higgs production respectively

Summary

Introduction

The demand for (sub-)percent precision in Drell–Yan production has led to formidable achievements in the theoretical description of corresponding collider observables, often pushing boundaries of technical limitations. The pioneering next-to-next-to-leading (NNLO) QCD corrections for differential Drell–Yan production [9,10,11] are available as public computer codes [12,13,14] and have recently been matched to QCD parton showers, using the UN2LOPS framework within SHERPA [15,16], and via a reweighting of a MiNLO improved calculation in DYNNLOPS [17]. Efforts to calculate the fixed-order NNLO mixed QCD and EW corrections explicitly are underway [46,47,48,49]. Their effect has been studied in the pole approximation [50,51]

Objectives

Results

Conclusion