Majorana Fermion Dark Matter in Minimally Extended Left-Right Symmetric Model

TL;DR

This paper proposes a minimal extension to the left-right symmetric model introducing a vector-like fermion as a Majorana fermion dark matter candidate, analyzing its phenomenology and constraints from collider and cosmological data.

Contribution

It introduces a new minimal model extension with a vector-like fermion, generating Majorana masses and exploring its viability as dark matter within existing experimental constraints.

Findings

Identifies a narrow parameter space consistent with relic density and collider constraints.

Predicts that future High-Luminosity LHC experiments can test most of the allowed parameter region.

Demonstrates the model's compatibility with perturbativity up to the Planck scale.

Abstract

We present a minimal extension of the left-right symmetric model based on the gauge group $SU(3)_{c} \times SU(2)_{L} \times SU(2)_{R} \times U(1)_{B-L} \times U(1)_{X}$, in which a vector-like fermion pair ($\zeta_L$ and $\zeta_R$) charged under the $U(1)_{B-L} \times U(1)_X$ symmetry is introduced. Associated with the symmetry breaking of the gauge group $SU(2)_{R} \times U(1)_{B-L} \times U(1)_{X}$ down to the Standard Model (SM) hypercharge $U(1)_Y$, Majorana masses for $\zeta_{L, R}$ are generated and the lightest mass eigenstate plays a role of the dark matter (DM) in our universe by its communication with the SM particles through a new neutral gauge boson "$X$". We consider various phenomenological constraints of this DM scenario, such as the observed DM relic density, the LHC Run-2 constraints from the search for a narrow resonance, and the perturbativity of the gauge couplings below the Planck scale. Combining all constraints, we identify the allowed parameter region which turns out to be very narrow. A significant portion of the currently allowed parameter region will be tested by the High-Luminosity LHC experiments.