Higgs Quark Flavor Violation: Simplified Models and Status of General Two-Higgs-Doublet Model

Juan Herrero-Garcia, Miguel Nebot, Filip Rajec, Martin White, Anthony G. Williams
2020 Journal of High Energy Physics  
We study quark flavor violating interactions mediated by the Higgs boson h. We consider observables involving a third generation quark, of both the up and the down quark sectors, like h → bs and t → ch. Using an effective field theory approach we systematically list all the possible tree-level ultraviolet completions, which comprise models with vector-like quarks and/or extra scalars. We provide upper bounds on the flavor violating transitions allowed by current limits stemming from low energy
more » ... ng from low energy processes, such as meson mixing and b → sγ. We find that scenarios with vector-like quarks always have very suppressed flavor-violating transitions, while a general Two-Higgs-Doublet Model may have a sizeable rate. To study the latter case in detail, we perform a full numerical simulation taking into account all relevant theoretical and phenomenological constraints. Our results show that BR(t → ch) [BR(h → bs)] are still allowed at the sub-percent [percent] level, which are being [may be] explored at the LHC [future colliders]. Finally, we have found that the mild mass-splitting discrepancy with respect to the SM in the B s meson system can be accommodated in the Two-Higgs-Doublet Model. If confirmed, it yields the prediction BR(h → bs) 10 −4 , if the new contribution to the mass-splitting is dominated by tree-level Higgs boson exchange.
doi:10.1007/jhep02(2020)147 fatcat:36kk4wsjrvh7nmv667zfu2bknm