Probing the C P nature of the top quark Yukawa at hadron colliders
Darius A. Faroughy, Jernej F. Kamenik, Nejc Košnik, Aleks Smolkovič
Abstract
A bstract We analyze the prospects of probing the C P -odd $$ i\tilde{\kappa}\overline{t}\gamma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>i</mml:mi> <mml:mover> <mml:mi>κ</mml:mi> <mml:mo>˜</mml:mo> </mml:mover> <mml:mover> <mml:mi>t</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> <mml:mi>γ</mml:mi> </mml:math> 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 $$ \tilde{\kappa} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mover> <mml:mi>κ</mml:mi> <mml:mo>˜</mml:mo> </mml:mover> </mml:math> . 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 $$ \tilde{\kappa} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mover> <mml:mi>κ</mml:mi> <mml:mo>˜</mml:mo> </mml:mover> </mml:math> . We project future sensitivity to the signal in pp → t ( → ℓ𝜈b ) h ( → b $$ \overline{b} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mover> <mml:mi>b</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> ) j . We also propose novel C P -odd observables for top quark pair production in association with the Higgs, pp → t $$ \overline{t} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mover> <mml:mi>t</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> h , with semileptonically decaying tops and h → b $$ \overline{b} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mover> <mml:mi>b</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> , 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 $$ \tilde{\kappa} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mover> <mml:mi>κ</mml:mi> <mml:mo>˜</mml:mo> </mml:mover> </mml:math> ∼ 0 . 1 at the high-energy LHC with 2𝜎 confidence.