Model building for flavor changing Higgs couplings

Abstract

If t → hq (q = c, u) or h → τ ℓ (ℓ = µ, e) decays are observed, it will be a clear signal of new physics. We investigate whether natural and viable flavor models can saturate the present direct upper bounds without violating the indirect constraints from low energy loop processes. We carry out our analysis in two theoretical frameworks: minimal flavor violation (MFV) and Froggatt-Nielsen symmetry (FN). The simplest models in either framework predict flavor changing couplings that are too small to be directly observed. Yet, in the MFV framework, it is possible to have lepton flavor changing Higgs couplings close to the bound if spurions related to heavy singlet neutrinos play a role. In the FN framework, it is possible to have large flavor changing couplings in both the up and the charged lepton sectors if supersymmetry plays a role.

$$\mu \rightarrow e \gamma $$ μ → e γ in the 2HDM: an exercise in EFT

“…The decay μ → eγ has been extensively studied in the 2HDM [3,[15][16][17][18][19][20][21][22][23][24][25][26][27], particularily in connection [29][30][31][32][33][34][35][36][37] with the recent LHC [28,38] excess in h → τ ± μ ∓ . Chang, Hou and Keung [5] (CHK) calculate the contributions to μ → eγ of neutral Higgs bosons with flavour-changing couplings.…”

Higgs decay h → μτ with minimal flavor violation

“…Subsequent to the h → µτ announcement by CMS, its signal hypothesis was theoretically examined in the contexts of various scenarios involving enlarged scalar sectors [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] or nonrenormalizable effective interactions [39][40][41][42][43][44].…”

Two Higgs doublets to explain the excesses pp → γγ(750 GeV) and h → τ ± μ ∓

“…This model has been studied before [104][105][106][107][108][109][110], and, with renewed interest, after the CMS excess was announced [111][112][113][114][115][116][117]. The aim of the present paper is to study whether a simple 2HDM could explain both the diphoton excess and the LFV Higgs decay.…”