FCNC, CP violation and implications for some rare decays in an SU(4)_L X U(1)_X extension of the standard model

Abstract

Extensions of the standard model (SM) with gauge symmetry SU (3)c ⊗ SU (4)L ⊗ U (1)X (3-4-1 extensions) where anomaly cancellation takes place between the fermion families (three-family models) predict the existence of two new heavy neutral gauge bosons which transmit flavor changing neutral currents (FCNC) at tree-level. In this work, in the context of a three-family 3-4-1 extension which does not contain particles with exotic electric charges, we study the constraints coming from neutral meson mixing on the parameters of the extension associated to tree level FCNC effects. Taking into account experimental measurements of observables related to K and B meson mixing and including new CP-violating phases, we study the resulting bounds for angles and phases in the mixing matrix for the down-quark sector, as well as the implications of these bounds for the modifications in the amplitudes of the clean rare decays K + → π + νν, KL → π 0 ν ν, KL → π 0 l + l − (l = e, µ) and B d/s → µ + µ − .

A new anomaly free flipped 341 model

“…In this paper, we are interested in a specific BSM model based on the Lie gauge group SU (3) C ⊗ SU (4) L ⊗ U (1) X (denoted by 341 for short) [1]. Many interest has been devoted to this kind of models especially those related to the LHC physics [1,8]. The most attractive feature of those models is the explanation of the family replication coming from the triangle gauge anomaly cancellation which together with QCD asymptotic freedom, requires that only three fermion families might be present in the spectrum, as in the 331 models.…”

“…It is worth to mention that the 341 models were also classified according to the scalars sectors [5,8]. Moreover, the self consistency of any BSM model is to be free from gauge anomalies.…”

Electroweak unification of quarks and leptons in a gauge group $SU_{C}(3)\times SU(4)\times U_{X}(1)$

“…Although leptons of standard model can be assigned to the representation 4 R or equivalently 4 * L , the cancelation of anomaly requires Hahn-Nambu quarks [2] with integral charges. Several models based on the extension of SU(4) to the semi-simple group SU C (3) × SU (4) × U (1) have been constructed [3]- [7]. However all these models require extra quarks and leptons beyond those of standard model group SU C (3) × SU L (2) × U Y (1).…”