Towards W b bbar + j at NLO with an automatized approach to one-loop computations

TL;DR

This paper introduces an automated method for calculating one-loop virtual corrections in QCD processes involving W bosons and b quarks, improving efficiency and stability for NLO and NNLO computations.

Contribution

The authors develop and validate a new automated approach for evaluating one-loop amplitudes in QCD, applicable to W b bbar + j production at NLO and relevant for NNLO calculations.

Findings

Method shows improved evaluation time.

Method demonstrates high numerical stability.

Results agree with existing NLO amplitude calculations.

Abstract

We present results for the O(alpha_s) virtual corrections to q g -> W b bbar q' obtained with a new automatized approach to the evaluation of one-loop amplitudes in terms of Feynman diagrams. Together with the O(alpha_s) corrections to q q' -> W b bbar g, which can be obtained from our results by crossing symmetry, this represents the bulk of the next-to-leading order virtual QCD corrections to W b bbar + j and W b + j hadronic production, calculated in a fixed-flavor scheme with four light flavors. Furthermore, these corrections represent a well defined and independent subset of the 1-loop amplitudes needed for the NNLO calculation of W b bbar. Our approach was tested against several existing results for NLO amplitudes including selected O(alpha_s) one-loop corrections to W + 3 j hadronic production. We discuss the efficiency of our method both with respect to evaluation time and numerical stability.