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PHYSICAL REVIEW D 94, 015007 (2016)

ISSN: 2470-0010, SCI

Electroweak theory based on SU(4)_L x U(1)_X gauge group

H. N. Long, L. T. Hue, and D. V. Loi

This paper includes two main parts. In the first part, we present generalized gauge models based on the SU(3)_C ⊗ SU(4)_L ⊗ U(1)_X (3-4-1) gauge group with arbitrary electric charges of exotic leptons. The mixing matrix of neutral gauge bosons is analyzed, and the eigenmasses and eigenstates are obtained. The anomaly-free as well as matching conditions are discussed precisely. In the second part, we present a new development of the original 3-4-1 model [R. Foot, H. N. Long, and T. A. Tran, Phys. Rev. D 50, R34 (1994), F. Pisano and V. Pleitez, Phys. Rev. D 51, 3865 (1995).]. Different from previous works, in this paper the neutrinos, with the help of the scalar decuplet H, get the Dirac masses at the tree level. The vacuum expectation value (VEV) of the Higgs boson field in the decuplet H acquiring the VEV responsible for neutrino Dirac mass leads to mixing in separated pairs of singly charged gauge bosons, namely the Standard Model (SM) W boson and K, the new gauge boson acting in the right-handed lepton sector, as well as the singly charged bileptons X and Y. Due to the mixing, there occurs a right-handed current carried by the W boson. From the expression of the electromagnetic coupling constant, ones get the limit of the sine-squared of theWeinberg angle, sin^2θ_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 boson. Some phenomenology is discussed.

DOI: 10.1103/PhysRevD.94.015007