LHC Phenomenology of Z ' and Z '' bosons in the SU(4)(L) x U(1)(X) little Higgs model

Abstract

We examine the direct limits on masses of extra neutral gauge bosons in the SU(4)(L) x U(1)(X) model with a little Higgs mechanism confronted with the Large Hadron Collider (LHC) data, especially by embedding an anomaly-free set of fermions. There exist two extra neutral gauge bosons, called Z' and Z '', in this model. The lower exclusion limit of the mass of the lighter extra neutral gauge boson is about 3 TeV, while that of the heavier one is 5 TeV. For comparison, we examine the mass limit of the Z(3)' boson in the SU (3)(L) x U(1)(X) model as well and discuss the implication of our result in the SU(4)(L) x U(1)(X) model with a standard Higgs mechanism. We also discuss the discovery potential of Z' and Z '' at the future LHC with a center-of-momentum energy of 14 TeV. Our results can be applicable to models with a regular Higgs mechanism if the same type of fermion family is assigned.