Recent Developments in Higher-Order Calculations: Hard Functions at NLO with GoSam

TL;DR

This paper discusses recent enhancements to the GoSam framework for higher-order QCD calculations, focusing on NLO hard functions for top-antitop production with vector bosons or Higgs, and explores future directions for multi-loop amplitude computations.

Contribution

It introduces a customized GoSam version for NLO hard function evaluation in complex processes and discusses ongoing efforts to extend integrand reduction techniques beyond one loop.

Findings

Successfully used GoSam to evaluate NLO hard functions for top-antitop plus boson/Higgs production.

Demonstrated the potential of the customized framework for advanced resummation calculations.

Outlined future research directions for multi-loop amplitude computation techniques.

Abstract

In this presentation, we will focus on a recent applications of the GoSam 2.0 automated framework which goes beyond the official scope of this code, originally designed for one-loop fixed order calculations. In particular, we describe a customized version of GoSam that has been recently employed to study the production of a top-antitop pair in association with a vector boson or with the Higgs boson to next-to-next-to-leading logarithmic accuracy. In the context of these calculations, the modified version of GoSam was used to evaluate the NLO hard functions which are needed to carry out the resummation of soft gluon emission effects. We also briefly comment on the ongoing efforts to generalize integrand reduction and unitarity for higher order calculation, towards the goal of developing efficient alternative computational techniques for the evaluation of scattering amplitudes beyond one loop.