Abstract
Flavor violating interactions of the Higgs boson are a generic feature of models with extended electroweak symmetry breaking sectors. Here, we investigate CP violation in these interactions, which can arise from interference of tree-level and 1-loop diagrams. We compute the CP asymmetry in flavor violating Higgs decays in an effective field theory with only one Higgs boson and in a general Type-III Two Higgs Doublet Model (2HDM). We find that large $$ \left(\sim \mathcal{O}\left(10\%\right)\right) $$ asymmetries are possible in the 2HDM if one of the extra Higgs bosons has a mass similar to the Standard Model Higgs. For the poorly constrained decay modes h → τμ and h → τe, this implies that large lepton charge asymmetries could be detectable at the LHC. We quantify this by comparing the sensitivity of the LHC to existing direct and indirect constraints. Interestingly, detection prospects are best if Higgs mixing is relatively small — a situation that is preferred by the current data. Nevertheless, CP violation in h → τμ or h → τe will only be observable if nonzero rates for these decay modes are measured very soon.
Highlights
JHEP10(2014)156 where i, j = {e, μ, τ } and i = j
We begin by considering a simple low energy effective field theory (EFT) of the Higgs sector, assuming that new physics which leads to flavor and CP violation can be integrated out
We investigated the prospects for discovering a CP asymmetry in the flavorviolating Higgs decays h → τ μ and h → τ e at the LHC
Summary
We begin by considering a simple low energy effective field theory (EFT) of the Higgs sector, assuming that new physics which leads to flavor and CP violation can be integrated out (see II of [15]). For example in [42] in order to avoid tunings, relations like the following have to hold Despite this general expectation one has to remark that the size of the flavor violating couplings is encoded in the details of the ultraviolet theory and in several explicit models larger flavor violating effects will be possible. When all three lepton generations experience flavor changing Higgs couplings, AμCτP receives additional contributions that do not depend on lepton masses, but are proportional to a product of three flavor violating Yukawa couplings involving all three flavor combinations eμ, eτ and μτ. In this case, large CP asymmetries are possible
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