Measuring CP nature of top-Higgs couplings at the future Large Hadron electron Collider

We investigate the sensitivity of top-Higgs coupling by considering the associated vertex as CP phase (xi(t)) dependent through the process pe(-) (t) over barh nu(e) in the future Large Hadron electron Collider. In particular the decay modes are taken to be h -> b (b) over bar and (t) over bar -> leptonic mode. Several distinct xi(t) dependent features are demonstrated by considering observables like cross sections, top-quark polarisation, rapidity difference between h and (t) over bar and different angular asymmetries. Luminosity (L) dependent exclusion limits are obtained for xi(t) by considering significance based on fiducial cross sections at different sigma-levels. For electron and proton beam-energies of 60 GeV and 7 TeV respectively, at L = 100 fb(-1), the regions above pi/5 < xi(t) <= pi are excluded at 2 sigma confidence level, which reflects better sensitivity expected at the Large Hadron Collider. With appropriate error fitting methodology we find that the accuracy of SM top-Higgs coupling could be measured to be K =1.00 +/- 0.17(0.08) at root s = 1.3(1.8) TeV for an ultimate L = 1 ab(-1). (C) 2017 The Author(s). Published by Elsevier B.V.