A flipped $U(1)_R$ extension of the Standard Model

TL;DR

This paper proposes a novel extension of the Standard Model with an additional $U(1)$ symmetry where only right-handed fermions carry charge, exploring its theoretical structure, experimental constraints, and potential signals at future colliders.

Contribution

It introduces a flipped $U(1)_R$ extension of the Standard Model, detailing anomaly cancellation, neutrino mass generation, and collider phenomenology.

Findings

Constraints from precision electroweak measurements are analyzed.

The model's parameter space is limited by current experimental bounds.

Potential signals at the ILC via forward-backward asymmetry are discussed.

Abstract

In this work, we study an extension of the Standard Model (SM) based on the gauge symmetry $SU(3)_C\times SU(2)_L\times U(1)_{Y'}\times U(1)_R$ where only the right-handed fermions have nonzero $U(1)_R$ charge and the $U(1)_Y$ weak hypercharge of the SM is identified as a combination of the $U(1)_{Y'}$ and $U(1)_R$ charges. The gauge charge assignment of the fields is constrained by the conditions of the anomaly cancellation and the gauge invariance of the Yukawa couplings. The light neutrino masses are generated via the type-I seesaw mechanism where the Majorana masses of the right-handed neutrinos are related to the $U(1)_{Y'}\times U(1)_R$ symmetry breaking scale. Then, we discuss the constraints on the free parameters of the model from the various current experiments, such as precision measurement of the total $Z$ width, $\rho$ parameter, atomic parity violation of Cesium, LEP and LHC bounds. In addition, we investigate the potential of probing for the signal of the new neutral gauge boson based on the forward-backward asymmetry for the process $e^+e^-\rightarrow\mu^+\mu^-$ which is the most sensitive mode at ILC.