Signatures of Higgs Bosons in the Top Quark Decay Channel at Hadron Colliders
W. Bernreuther, M. Flesch, P. Haberl
TL;DR
Extended Higgs sectors can host heavy neutral bosons with large $t\bar{t}$ couplings and suppressed couplings to vector bosons. The authors derive a general LO framework including interference between gluon-fusion production and QCD $t\bar{t}$ background, and implement a Monte Carlo to study the $t\bar{t}$ invariant-mass spectrum and $t\bar{t}$ spin-spin correlations. They show that at LHC energies the $(M_{t\bar{t}})$ spectrum can reveal a peak-dip signature near $m_\varphi$ and that spin correlations, especially the lab-frame lepton-angle observable, are sensitive to a sizeable pseudoscalar component, allowing CP information to be extracted. The results provide a pathway to identifying and characterizing neutral Higgs bosons with strong top couplings, while noting the need for higher-order corrections and detector effects in a full phenomenological analysis.
Abstract
We analyze some signatures of neutral Higgs bosons, produced in high energy proton (anti)proton collisions, which decay primarily to top quarks. This channel is clouded by a large irreducible $t\bar t$ background. We investigate the $t\bar t$ invariant-mass distribution in the lepton+jets decay mode of $t\bar t$ and a $t\bar t$ spin-spin correlation in the dilepton decay mode. At the LHC such Higgs bosons can be detected in the $t\bar t$ invariant-mass spectrum, and the spin-spin correlation studied by us is also sensitive to a Higgs boson if this particle has a sizeable pseudoscalar component.