Collider Tests of Flavored Resonant Leptogenesis in the $U(1)_X$ Model

TL;DR

This paper investigates flavored resonant leptogenesis within a $U(1)_X$ extension of the Standard Model, demonstrating its ability to explain baryon asymmetry, neutrino masses, and exploring collider detection prospects.

Contribution

It introduces a $U(1)_X$ model generalizing $U(1)_{B-L}$, analyzes flavored leptogenesis across different charge assignments, and assesses collider signals for testing the model.

Findings

All three $U(1)_X$ cases can explain baryon asymmetry within parameter space.

The $U(1)_C$ model offers larger viable parameter space for leptogenesis.

Future colliders can probe significant regions of the model's parameter space.

Abstract

We study the generation of baryon asymmetry through the flavored resonant leptogenesis in the $U(1)_X$ extension of the Standard Model. Being a generalization of the $U(1)_{B\text{-}L}$, $U(1)_X$ is an ultraviolet-complete model of the right-handed neutrinos (RHNs), whose CP violating out-of-equilibrium decays lead to the generation of baryon asymmetry via leptogenesis. We can also explain the neutrino masses via the seesaw mechanism in this model. We consider three different cases for different $U(1)_X$ charges of the scalar particle responsible for $U(1)_X$ breaking at TeV-scale. These include the popular $U(1)_{B\text{-}L}$ and $U(1)_{R}$ models, as well as a $U(1)_C$ model which maximizes the collider signal. We numerically solve the flavored Boltzmann transport equations to calculate the total baryon asymmetry. We show that all three cases considered here can naturally explain the observed baryon asymmetry of the Universe in a large portion of the available parameter space, while satisfying the neutrino oscillation data. We find that the $U(1)_C$ case offers successful leptogenesis in a larger portion of the parameter space as compared to $U(1)_{B\text{-}L}$ and $U(1)_{R}$. We also perform a comparative study between the flavored and unflavored leptogenesis parameter space. Finally, we also study the collider prospects for all these scenarios using the lepton number violating signal of $pp\to \ell^\pm \ell^\pm+$jets mediated by the $Z'$ boson associated with $U(1)_X$. We find that HL-LHC may be able to probe a small portion of the relevant parameter space having successful leptogenesis, if neutrinos have normal mass ordering, while a $\sqrt s=100$ TeV future collider can access a much larger region of the parameter space, thereby offering an opportunity to test resonant leptogenesis in the $U(1)_X$ model.