Disentangling Higgs-top couplings in associated production

A bstractIn the presence of CP violation, the Higgs-top coupling may have both scalar and pseudoscalar components, κt and $ {{\widetilde{\kappa}}_t} $, which are bounded indirectly but only weakly by the present experimental constraints on the Higgs-gluon-gluon and Higgs-γ-γ couplings, whereas upper limits on electric dipole moments provide strong additional indirect constraints on $ {{\widetilde{\kappa}}_t} $, if the Higgs-electron coupling is similar to that in the Standard Model and there are no cancellations with other contributions. We discuss methods to measure directly the scalar and pseudoscalar Higgs-top couplings by measurements of Higgs production in association with $ \overline{t}t $, single t and single $ \overline{t} $ at the LHC. Measurements of the total cross sections are very sensitive to variations in the Higgs-top couplings that are consistent with the present indirect constraints, as are invariant mass distributions in $ \overline{t}tH $, tH and $ \overline{t}H $ final states. We also investigate the additional information on κt and $ {{\widetilde{\kappa}}_t} $ that could be obtained from measurements of the longitudinal and transverse t polarization in the different associated production channels, and the $ \overline{t}t $ spin correlation in $ \overline{t}tH $ events.