Leptoquark induced rare decay amplitudesh→τ∓μ±andτ

Kingman Cheung

¹

,

Wai-Yee Keung

²

,

Po-Yan Tseng

³

Abstract

Rare decay modes of the newly discovered standard-model-like Higgs boson h may test the flavor changing couplings in the leptoquark sector through the process h → τ ∓ µ ± . Motived by the recently reported excess in LHC data from the CMS detector, we found that a predicted branching fraction Br(h → τ ∓ µ ± ) at the level of 1% is possible even though the coupling parameters are subjected to the stringent constraint from the null observation of τ → µγ, where the destructive cancellation among amplitudes is achievable by fine tuning.

Charged-lepton-flavor violation in |ΔS| = 1 hyperon decays

“…To illustrate how L np may be generated by renormalizable NP interactions, we look at the leptoquark (LQ) scenario. Amongst those that have been explored in the literature [12][13][14][15][16][17][18][19][20][21][22], with couplings to SM fermions which conserve baryon and lepton numbers and respect SM gauge symmetries, the LQs (with their SU(3) c × SU(2) L × U(1) Y assignments) that can bring about L np are S 1 3 , 1, 4/3 , S 2 (3, 2, 7/6),S 2 (3, 2, 1/6), and S 3 3 , 3, 1/3 , which are spinless, and V 1 (3, 1, 2/3), V 2 3 , 2, 5/6 , and V 3 (3, 3, 2/3), which have spin 1. The SU(2) L doublets (triplets) S 2 ,S 2 , and V 2 (S 3 and V 3 ) each have two (three) components having different electric charges.…”

“…Many extensions of the SM do not preserve lepton-flavor number, and the corresponding parameters have been tightly restricted by the negative outcomes of the various searches conducted so far in the decays of kaons, B mesons, and charged leptons, among others [1][2][3][4][5][6][7][8][9][10][11]. The most common examples of NP exhibiting LFV include leptoquarks [12][13][14][15][16][17][18][19][20][21][22], heavy neutrinos [23][24][25][26][27][28][29][30][31][32], gauged U(1) extensions of the SM with their associated Z gauge bosons [33][34][35][36][37][38][39][40][41], and multi-Higgs models [42][43][44][45][46][47]…”

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

“…Higher dimensional operators in the effective theory framework were also considered [19,23,28,29]. But at loop level a large cancellation probably is needed to evade the CLFV constraint [19,30,31]. Other scenarios can be found in ref.…”

Higgs lepton flavour violation: UV completions and connection to neutrino masses

“…Within particular models, different flavour structures have been considered, such as minimal flavor violation [28][29][30][31][32], natural flavour conservation [33], Frogatt Nielsen models [29,33,34], flavor symmetries [35] and discrete symmetries [36][37][38]. Several of the models proposed to explain the anomaly require severe fine-tuning among different parameters, in order to cancel too large contributions to charged lepton flavour violation (CLFV) processes [21,[39][40][41].…”