The electroweak theory based on SU(4)_L X U(1)_X gauge group

TL;DR

This paper develops a generalized SU(4)_L x U(1)_X gauge model for electroweak interactions, introduces neutrino masses via a Higgs decuplet, and analyzes gauge boson mixing and phenomenology.

Contribution

It presents a new 3-4-1 gauge model with neutrino Dirac masses at tree level and detailed analysis of gauge boson mixing and phenomenological constraints.

Findings

Neutrinos acquire Dirac masses through Higgs decuplet VEVs.

Derived limits on sin^2 θ_W and electric charges of extra leptons.

Identified mixing effects leading to right-handed currents in W bosons.

Abstract

This paper includes two main parts. In the first part, we present generalized gauge models based on SU(3)_C x SU(4)_L x U(1)_X (3-4-1) gauge group with arbitrary electric charge of leptons. The mixing matrix of neutral gauge bosons is analysed, the eigenmasses and eigenstates are obtained. The anomaly free as well as matching conditions are discussed precisely. In the second part, we present new development of the original 3-4-1 model [1,2]. In difference from previous works, in this paper the neutrinos, with the help of the decuplet H, get the Dirac masses at the tree level. The VEV of the Higgs field in the decuplet H acquiring VEV responsible for neutrino Dirac mass leads to mixing in separated pairs of singly charged gauge bosons, namely the SM W boson and K - new gauge boson acting in right-handed lepton sector, and the singly charged bileptons X and Y. Due to the mixing, there occurs a right-handed current carried by the SM W bosons. From the expression of the electromagnetic coupling constant, ones get the limit of square sinus of the Weinberg angle: sin^2 \theta_W < 0.25 and a constraint on electric charges of extra leptons. In the limit of lepton number conservation, the Higgs sector contains all massless Goldstone bosons for massive gauge bosons and the SM-like Higgs. Some phenomenology are pointed out.