Constraining models with extra heavy gauge bosons using LHC measurements

TL;DR

This paper enhances calculations of electroweak top-antitop production in models with extra heavy gauge bosons, incorporating NLO QCD corrections, interference effects, and flavor-non-diagonal couplings to improve LHC-based BSM constraints.

Contribution

It introduces an improved computational framework for electroweak top pair production in models with heavy gauge bosons, including non-resonant effects and interference, for more accurate LHC constraints.

Findings

Enhanced calculation accuracy for BSM models with heavy gauge bosons.

Application of the method to set limits on the leptophobic Topcolour model.

Integration with the Contur framework for experimental constraints.

Abstract

We discuss significant improvements to our calculation of electroweak (EW) $t\bar{t}$ hadroproduction in extensions of the Standard Model (SM) with extra heavy neutral and charged spin-1 resonances using the Recola2 package. We allow for flavour-non-diagonal $Z'$ couplings and take into account non-resonant production in the SM and beyond including the contributions with t-channel $W$- and $W'$-bosons. We include next-to-leading order (NLO) QCD corrections and consistently match to parton showers with the POWHEG method fully taking into account the interference effects between SM and new physics amplitudes. We briefly describe the Contour method and give some information about the Rivet repository which catalogues particle-level measurements subsequently used by Contur to set limits on beyond the SM (BSM) theories. We explain how we use our calculation within Contour in order to set limits on models with additional heavy gauge bosons using LHC measurements, and illustrate this with an example using the leptophobic Topcolour (TC) model.