Probing the C P nature of the top quark Yukawa at hadron colliders

Abstract

Abstract We analyze the prospects of probing the C P -odd i κ ˜ t ¯ γ $$ i\tilde{\kappa}\overline{t}\gamma $$ 5 th interaction at the LHC and its projected upgrades, the high-luminosity and high-energy LHC, directly using associated on-shell Higgs boson and top quark or top quark pair production. To this end we first construct a C P -odd observable based on top quark polarization in Wb → th scattering with optimal linear sensitivity to κ ˜ $$ \tilde{\kappa} $$ . For the corresponding hadronic process pp → thj we present a method of extracting the phase-space dependent weight function that allows to retain close to optimal sensitivity to κ ˜ $$ \tilde{\kappa} $$ . We project future sensitivity to the signal in pp → t(→ ℓ𝜈b)h(→ b b ¯ $$ \overline{b} $$ )j. We also propose novel C P -odd observables for top quark pair production in association with the Higgs, pp → t t ¯ $$ \overline{t} $$ h, with semileptonically decaying tops and h → b b ¯ $$ \overline{b} $$ , that rely solely on measuring the momenta of leptons and b-jets from the decaying tops without having to distinguish the charge of the b-jets. Among the many possibilities we single out an observable that can potentially probe κ ˜ $$ \tilde{\kappa} $$ ∼ 0.1 at the high-energy LHC with 2𝜎 confidence.

Keywords

• Higgs Physics
• CP violation
• Beyond Standard Model