Lepton masses and mixing in a two-Higgs-doublet model

Abstract

Within the framework of the two-Higgs Doublet Model (2HDM), we attempt to find some discrete, non-abelian flavour symmetry which could provide an explanation for the masses and mixing matrix elements of leptons. Unlike the Standard Model, currently there is no need for the flavour symmetry to be broken. With the GAP program we investigate all finite subgroups of the U3 group up to the order of 1025. Up to such an order there is no group for which it is possible to select free model parameters in order to match the masses of charged leptons, masses of neutrinos, and the Pontecorvo-Maki-Nakagawa-Sakata mixing matrix elements in a satisfactory manner.

Family Symmetries and Multi Higgs Doublet Models

“…The same conclusion is valid if one assumes that neutrinos have Majorana nature. In such a frame, the Yukawa interaction Lagrangian has to be rewritten in an appropriate way (see [11]) producing family symmetry condition in the form:…”

“…Non trivial mixing can be also achieved by extending the Higgs sector by additional multiplets (e.g., [8,9]). A proposal for the two Higgs doublet model (2HDM) [10] was widely discussed in [11]. In the most general situation, the mass generation mechanism allows couplings with various Higgs fields.…”

“…Theoretical proposals assuming the existence of two Higgs fields are not the only possible and potentially experimentally verifiable space for applying the symmetry implementation. In this paper, the methodology proposed previously for 2HDM only [11] is extended to any number of additional Higgs fields.…”

“…Additionally, new forms of results, equivalent to [11], for 2HDM are given. The obtained results depend on many phases and we present here a more detailed discussion concerning relations between them.…”

The signatures of the new particles $$h_{2}$$ and $$Z^{}_{\mu \tau }$$ at e-p colliders in the $${U(1)}_{L^{}_{\mu } - L^{}_{\tau } }$$ model

“…In order to address the above issues, there are many well motivated extensions of the SM like SUSY [14][15][16][17], two Higgs doublet model [18][19][20][21][22][23], extension of the SM with an extra U (1) gauge group [24][25][26][27] and many more. In this work, we have considered the gauged U (1) L µ −L τ extension of the SM due to its relatively simple theoretical structure and background free environment, which has a complete gauge group SU (3) C × SU (2) L × U (1) Y × U (1) L µ −L τ and is called the U (1) L µ −L τ model [28][29][30][31][32][33][34][35].…”