Higgs boson-μ−τcoupling at high and low energy colliders

Abstract

There is no tree-level flavor changing neutral current (FCNC) in the standard model (SM) which contains only one Higgs doublet. If more Higgs doublets are introduced for various reasons, the tree level FCNC would be inevitable except extra symmetry was imposed. Therefore FCNC processes are the excellent probes for the physics beyond the SM (BSM). In this paper, we studied the lepton flavor violated (LFV) decay processes h → µτ and τ → µγ induced by Higgs-µ-τ vertex. For τ → µγ, its branching ratio is also related to the htt, hτ + τ − and hW + W − vertices.We categorized the BSM into two scenarios for the Higgs coupling strengths near or away from SM. For the latter scenario, we took the spontaneously broken two Higgs doublet model (Lee model) as an example. We considered the constraints by recent data from LHC and B factories, and found that the measurements gave weak constraints. At LHC Run II, h → µτ will be confirmed or set stricter limit on its branching ratio. Accordingly, Br(τ → µγ)O(10 −10 − 10 −8 ) for general chosen parameters. For the positive case, τ → µγ can be discovered with O(10 10 )τ pair samples at SuperB factory, Super τ -charm factory and new Z-factory. The future measurements for Br(h → µτ ) and Br(τ → µγ) will be used to distinguish these two scenarios or set strict constraints on the correlations among different Higgs couplings, please see Table II in the text for details.

Naturally large radiative lepton flavor violating Higgs decay mediated by lepton-flavored dark matter

“…At tree level, two (or even more)-Higgs doublet model (2HDM) with proper flavor changing neutral current allows LFV Higgs decay which is large enough to explain the CMS excess [15][16][17][18][19][20][21][22][23][24][25]. Higher dimensional operators in the effective theory framework were also considered [19,23,28,29].…”

Higgs decay h → μτ with minimal flavor violation

“…This tantalizing, albeit tentative, hint of lepton flavor violation (LFV) outside the neutrino sector has attracted a growing amount of attention, as the detection of such a process would serve as a test for many models [9][10][11][12][13][14][15][16][17][18][19][20][21][22] and could have major implications for upcoming Higgs measurements [22][23][24][25][26][27][28]. 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].…”

Sgoldstino physics and flavor-violating Higgs boson decays

“…According to the latest studies this level of branching fraction will be reachable at experiments on HL-LHC and ILC; see refs. [43][44][45]. We also make predictions for flavour-violating decays of τ-lepton (Fig.2),signal strength μ f for different final states f and Higgs production channels (Fig.3,4) and make predictions for observable σ(pp →s) × Br(s → W + W − or ZZ) for the case of 13 TeV (Figs.5,6).…”