SU(3)c⊗SU(4)L⊗<

Abstract

We present an extension of the standard model to the local gauge group SU(3) c SU(4) L U(1) X with a family nonuniversal treatment and anomalies canceled among the three families in a nontrivial fashion. The mass scales, the gauge boson masses, and the masses for the spin 1/2 particles in the model are analyzed. The neutral currents coupled to all neutral vector bosons in the model are studied, and particular values of the parameters are used in order to simplify the mixing between the three neutral currents present in the theory, mixing which is further constrained by experimental results from the CERN LEP, SLAC Linear Collider, and atomic parity violation.

Dimension-five effective operators in electroweakSU(4)L⊗U(1)Xgauge models

“…However, these theoretical bounds [7,8] are consistent with recent experimental observations [1] that suggest a lower bound around 1T eV for Z ′ . In order to ensure the consistency with the SM phenomenology, the heavy particles of the 3-4-1 symmetry must not compromise the precision tests of the SM, particularly the oblique corrections must remain unaffected.…”

“…µ couples only with exotic fermions having no interaction with ordinary particles and thus totally decoupling from the low energy phenomenology, while Z ′ mixes with the SM Z and exhibits a mass ( [7,8]) lower bounded by 2T eV (or greater), in close dependence on which one of the three generations of quarks transforms differently from the other two. The restrictions on the Z ′ neutral boson come from plugging into this model the data supplied by atomic parity violation experiments and certain processes in the meson systems…”

“…As long as they are sterile with respect to Z and exhibit indistinguishable couplings to the new Z ′ and Z ′′ bosons (see for instance Ref. [8]) This assumption leads straightforwardly to the following identification:…”

“…However, the reader can find its phenomenological details treated in extenso in Refs. [8]. Evidently, our focus will go to its lepton sector, as we intend to exploit the realization of dimension-five effective operators responsible for giving rise (at the tree level) to the well known seesaw terms.…”

“…In 3-4-1 models the same strategy was considered in Refs. [8] where a new Higgs decaplet is introduced in the scalar sector of the model in order to set up proper seesaw terms. Yet, this can affect the boson masses previously calculated, while some ad hoc hypothesis on the breaking scales of the decaplet must be speculated.…”