Top Hypercharge

TL;DR

This paper introduces a top hypercharge model with an extended gauge symmetry that differentiates the third fermion family from the first two, exploring its phenomenological implications and experimental constraints.

Contribution

It proposes a novel gauge symmetry structure with family-dependent hypercharges and analyzes its effects on flavor physics, dark matter, and collider phenomenology.

Findings

The model fits electroweak precision data better than the Standard Model.

Predictions for Z' boson discovery potential at the LHC are provided.

Implications for neutrino masses, mixing, and dark matter are discussed.

Abstract

We propose a top hypercharge model with gauge symmetry SU(3)_C x SU(2)_L x U(1)_1 x U(1)_2 where the first two families of the Standard Model (SM) fermions are charged under U(1)_1 while the third family is charged under U(1)_2. The U(1)_1 x U(1)_2 gauge symmetry is broken down to the U(1)_Y gauge symmetry, when a SM singlet Higgs field acquires a vacuum expectation value. We consider the electroweak constraints, and compare the fit to experimental observables to that of the SM. We study the quark CKM mixing between the first two families and the third family, the neutrino masses and mixing, the flavour changing neutral current effects in meson mixing and decays, the Z' discovery potential at the Large Hadron Collider, the dark matter with a gauged Z_2 symmetry, and the Higgs boson masses.