$B-L$ model in light of the CDF II result

TL;DR

This paper explores how a $U(1)_{B-L}$ extension of the Standard Model can explain the CDF II $W$ mass anomaly by affecting the $Z$ boson mass, aligning with experimental and dark matter constraints.

Contribution

It proposes that modifications to the $Z$ boson mass in $B-L$ models can account for the $W$ mass discrepancy observed by CDF II, offering a new perspective on potential new physics.

Findings

$B-L$ models can fit the CDF II $W$ mass results.

Parameter space exists consistent with dark matter constraints.

Models without gauge boson mixing are also viable.

Abstract

Recent CDF II collaboration's result on $W$ mass measurements contradict Standard Model prediction, requiring new physics to explain this anomaly. Such new physics may manifest through tree-level or loop-level corrections to the mass of the $W$ boson. In this work, we investigate the possibility that the CDF-II result is indicative of new physics not directly changing the $W$ boson mass but rather the $Z$ boson mass. Since the $Z$ boson mass goes as an input into the Standard Model prediction for $W$ boson mass, this change in $Z$ mass ultimately leads to the discrepancy between the CDF-II measurement and the Standard Model expectation. We demonstrate this idea through one of the simplest and most studied $U(1)$ gauge extensions of the Standard Model, namely the gauged $U(1)_{B-L}$ extension. We demonstrate that $B-L$ extended models can explain the revised best-fit values for $S$, $T$, and $U$ following the CDF II results. We studied the parameter space of models with and without mixing between neutral gauge bosons. We also reviewed the dark matter constraints and demonstrated that there is parameter space that is compatible with the current $W$ boson mass, relic abundance, and direct detection experiments.