Electroweak Corrections at the LHC with MCFM

TL;DR

This paper calculates electroweak NLO corrections for key LHC processes, implements them in MCFM, and compares full results with Sudakov approximations to improve precision in high-energy predictions.

Contribution

It provides the first implementation of full NLO electroweak corrections for multiple LHC processes in MCFM, including Sudakov approximations for high-energy regimes.

Findings

Full NLO weak corrections implemented in MCFM

Comparison of exact and Sudakov approximation results

Enhanced accuracy for high-energy LHC predictions

Abstract

Electroweak (EW) corrections at the LHC can be enhanced at high energies due to soft/collinear radiation of W and Z bosons, being dominated by Sudakov-like corrections in the form of $\alpha_W^l\log^n(Q^2/M_W^2)$ $(n \le 2l, \alpha_W = \alpha/(4\pi\sin\theta_W^2))$ when the energy scale $Q$ enters the TeV regime. Thus, the inclusion of EW corrections in LHC predictions is important for the search of possible signals of new physics in tails of kinematic distributions. EW corrections should also be taken into account in virtue of their comparable size ($\mathcal{O}(\alpha)$) to that of higher order QCD corrections ($\mathcal{O}(\alpha_s^2)$). We calculated the next-to-leading-order (NLO) weak corrections to the neutral-current (NC) Drell-Yan process, top-quark pair production and di-jet producion, and implemented them in the Monte-Carlo program MCFM. This enables a combined study with the corresponding NLO QCD corrections. We provide both the full NLO weak corrections and their weak Sudakov approximation valid at high energies. The latter is often used for a fast evaluation of weak effects, and having the exact result available as well allows to quantify the validity of the Sudakov approximation.