CP tests of Higgs couplings in $t\bar{t}h$ semileptonic events at the LHC

Understand

The CP nature of the Higgs coupling to top quarks is addressed in this paper, in single charged lepton final states of $t\bar{t}h$ events produced in proton-proton collisions at the LHC.

• Pure scalar ($h=H$) and pseudo-scalar ($h=A$) Higgs boson signal events, generated with MadGraph5_aMC@NLO, are fully reconstructed using a kinematic fit.
• Angular distributions of the decay products, as well as CP-sensitive asymmetries, are exploited to separate and gain sensitivity to possible pseudo-scalar components of the Higgs boson and reduce the contribution from the dominant irreducible background $t\bar{t}b\bar{b}$.
• Significant differences are found between the pure CP-even and -odd signal hypotheses as well as with respect to the Standard Model background, in particular the $t\bar{t} b\bar{b}$ contribution.