Top SU(5) Models: Baryon and Lepton Number Violating Resonances at the LHC

TL;DR

This paper introduces minimal non-supersymmetric top SU(5) models with TeV-scale gauge symmetry breaking, predicting baryon and lepton number violating resonances that could be observed at the LHC.

Contribution

It presents two variants of top SU(5) models that address proton decay and quark mixing, and predicts new gauge bosons with potential LHC signatures.

Findings

CKM mixing generated via dimension-five operators or vector-like particles

Proton decay problem solved or suppressed in the models

Predicted leptoquark and diquark gauge bosons accessible at TeV scale

Abstract

We propose the minimal and renormalizable non-supersymmetric top SU(5) models where the $SU(5)\times SU(3)'_C \times SU(2)'_L \times U(1)'_Y$ gauge symmetry is broken down to the Standard Model (SM) gauge symmetry at the TeV scale. The first two families of the SM fermions are charged under $SU(3)'_C \times SU(2)'_L \times U(1)'_Y$ while the third family is charged under SU(5). In the minimal top SU(5) model, we show that the quark CKM mixing matrix can be generated via dimension-five operators, and the proton decay problem can be solved by fine-tuning the coefficients of the higher dimensional operators at the order of $10^{-4}$. In the renormalizable top SU(5) model, we can explain the quark CKM mixing matrix by introducing vector-like particles, and we do not have proton decay problem. The models give rise to leptoquark and diquark gauge bosons which violate both lepton and baryon numbers involving the third family quarks and leptons. The current experimental limits for these particles is well below the TeV scale. We also discuss the productions and decays of these new gauge bosons, and their ensuing signals, as well as their reach at the LHC.