Explaining the $R_{K^{(*)}}$ anomalies and the CDF $M_W$ in Flavorful Top Seesaw Models with Gauged $U(1)_{L(-R)}$

TL;DR

This paper proposes a modified Top Seesaw model with a TeV-scale Z' boson that explains B anomalies and the CDF W mass measurement, predicting new particles and interactions testable at colliders.

Contribution

It introduces a novel flavorful Top Seesaw model with gauged U(1)' symmetry, linking B anomalies and W mass shifts through a TeV-scale Z' and vector-like top quark.

Findings

A viable parameter space for the Z' explains B anomalies and W mass.

Predicted a light Higgs and large top Yukawa in the model.

Z' can be detected in dilepton channels at colliders.

Abstract

A new heavy $Z'$ vector boson provides a possible explanation for the neutral current B anomalies and points to the scale where we expect the solution to the hierarchy problem to appear. In this paper, we explore a modified Top Seesaw model based on the global symmetry breaking of $U(3)_L$ to $U(2)_L$. The symmetry is partially gauged such that the breaking introduces not only a composite Higgs doublet but also a TeV-scale $Z'$ boson. The $U(3)_L/U(2)_L$ Top Seesaw model predicts a light Higgs boson as well as a large top Yukawa coupling. Additional $U(1)'$ symmetry is gauged such that a flavorful TeV-scale $Z'$ boson is introduced to address the B anomalies. The existence of a heavy vector-like top quark and $Z-Z'$ mixing breaks the custodial symmetry, which predicts a heavier $W$ mass as observed by the CDF collaboration. Two possible candidates for the $U(1)'$ symmetry corresponding to the $Z'$ boson, $U(1)_L$ and $U(1)_{L-R}$, are discussed in detail. The parameter space for the models to address both anomalies is presented. The direct searches of the $Z'$ boson from dilepton channels are also studied. Based on the assumptions, a TeV-scale $Z'$ boson is still viable and can be probed in the near future.