A Comprehensive Framework for Studying $W'$ and $Z'$ Bosons at Hadron Colliders with Automated Jet Veto Resummation

Abstract

The production of high-mass, color-singlet particles in hadron colliders is universally accompanied by initial state QCD radiation that is predominantly soft with respect to the hard process scale $Q$ and/or collinear with respect to the beam axis. At TeV-scale colliders, this is in contrast to top quark and multijet processes, which, by definition, are hard and central. Consequently, vetoing events with jets possessing transverse momenta above $p_T^{\rm Veto}$ in searches for new color-singlet states can efficiently reduce non-singlet backgrounds, thereby increasing experimental sensitivity. To quantify this generic observation, we investigate the production and leptonic decay of a Sequential Standard Model $W'$ boson at the 13 TeV LHC. We systematically consider signal and background processes at next-to-leading-order (NLO) in QCD with parton shower (PS) matching; for color-singlet channels, we resum Sudakov logarithms of the form $α_s^j(p_T^{\rm Veto})\log^k(Q/p_T^{\rm Veto})$ up to next-to-next-to-leading logarithmic accuracy (NNLL) with NLO matching. We obtain our results using the MadGraph5aMC@NLO and MadGraph5aMC@NLO-SCET frameworks, respectively. Associated FeynRules model files capable of handling NLO+PS- and NLO+NNLL-accurate computations are publicly available. We find that within their given uncertainties, both the NLO+PS and NLO+NNLL(veto) calculations give accurate and consistent predictions. Consequently, jet vetoes applied to color-singlet processes can be reliably modeled at the NLO+PS level. With respect to a $b$-jet veto of $p_{T}^{\rm Veto} = 30$ GeV, flavor-agnostic vetoes of $p_{T}^{\rm Veto} = 30-40$ GeV can further reduce single top and $t\overline{t}$ rates by a factor of 2-50 at a mild cost of the signal rate. Jet vetoes can increase signal-to-noise ratios by roughly 10\% for light $W'$ boson masses of 30-50 GeV and 25\%-250\% for masses of 300-800 GeV.