Global Fits of Third Family Hypercharge Models to Neutral Current B-Anomalies and Electroweak Precision Observables

TL;DR

This paper performs comprehensive global fits of third family hypercharge models to both electroweak precision data and B-anomalies, demonstrating that certain model variants significantly improve fit quality over the Standard Model.

Contribution

It provides the first detailed analysis showing that simple third family hypercharge models can simultaneously fit electroweak and B-anomaly data with high statistical significance.

Findings

Standard Model is in tension with combined data (p-value 0.00068)

Certain hypercharge models significantly improve fit quality (e.g., p-value 0.065)

Original Third Family Hypercharge Model achieves a 6.5 sigma improvement.

Abstract

While it is known that third family hypercharge models can explain the neutral current $B-$anomalies, it was hitherto unclear whether the $Z-Z^\prime$ mixing predicted by such models could simultaneously fit electroweak precision observables. Here, we perform global fits of several third family hypercharge models to a combination of electroweak data and those data pertinent to the neutral current $B-$anomalies. While the Standard Model is in tension with this combined data set with a $p-$value of $.00068$, simple versions of the models (fitting two additional parameters each) provide much improved fits. The original Third Family Hypercharge Model, for example, has a $p-$value of $.065$, i.e. $\sqrt{\Delta \chi^2}=6.5\sigma$.