Scalar FCNC and rare top decays in a two Higgs doublet model "for the top"

Baum, Itzhak; Eilam, Gad; Bar-Shalom, Shaouly

Scalar FCNC and rare top decays in a two Higgs doublet model "for the top"

Authors

Baum, Itzhak

Eilam, Gad

Bar-Shalom, Shaouly

Description

In the so called two Higgs doublet model for the top-quark (T2HDM), first suggested by Das and Kao, the top quark receives a special status, which endows it with a naturally large mass, and also potentially gives rise to large flavor changing neutral currents (FCNC) only in the up-quark sector. In this paper we calculate the branching ratio (BR) for the rare decays t->ch and h->tc (h is a neutral Higgs) in the T2HDM, at tree level and at 1-loop when it exceeds the tree-level. We compare our results to predictions from other versions of 2HDM's and find that the scalar FCNC in the T2HDM can play a significant role in these decays. In particular, the 1-loop mediated decays can be significantly enhanced in the T2HDM compared to the 2HDM of types I and II, in some instances reaching BR~10^-4 which is within the detectable level at the LHC.
added two references. 15 pages, 14 figures