The phenomenoogy of extended gauge and higgs sectors at the LHC

Abstract

We consider prospects for detecting and measuring the properties of Z', W' and heavy Higgs bosons at the Large Hadron Collider (LHC). These particles are all well-motivated heavier counterparts to known SM particles. Z' and W0 bosons arise when the SM gauge group is extended with additional U(1) or SU(2) factors. Heavy Higgs bosons are a feature of many models, including the Two Higgs Doublet Model (2HDM), supersymmetric (SUSY) models, and W' and Z' models. First, we consider a number of common Z' models and present next-to-leading (NLO) and next-to-next-to-leading order (NNLO) predictions for the cross section, forwardbackward asymmetry, and rapidity distributions. We discuss methods for measuring the couplings of the Z' and distinguishing among models. Z' bosons with masses around 5 TeV should be detectable at the LHC, and the couplings of a 2.5 TeV Z' could be measured within 0.1π with a luminosity of 1 ab-1. We also consider a hidden sector Z' that couples to standard model fermions via kinetic and mass mixing and serves as a mediator of isospin-violating interactions with dark matter. We combine the results of LHC Z' searches and dark matter direct detection experiments with global electroweak data to obtain mass-dependent constraints on the model parameters. Next, we consider the fact that extra broken gauge symmetries are often accompanied by extended scalar sectors. If the masses of new Higgs particles are not too large, the W' bosons may decay into heavy Higgs particles, providing new possibilities for W' detection. We consider a simple scenario where the W' couplings to fermions are suppressed, making decays to scalar pairs the dominant decay mode. Potential final states include one or two gauge bosons plus missing energy. Finally, we turn our attention to Higgs pair production in the 2HDM. Higgs pair production is a valuable tool for measuring the triscalar couplings of the scalar potential. We consider both hh resonant production and hH associated production. We identify viable search channels for the LHC and provide their expected discovery sensitivities for a center-of-mass energy of 14 TeV (LHC14) and a luminosity of 3 ab-1. We nd that discovery at the 95% C.L. is possible over most of the parameter space of the CP-conserving Type-II 2HDM.