# $R_K$ anomalies and simplified limits on $Z'$ models at the LHC

## TL;DR

This paper investigates $Z'$ models as explanations for the LHCb $R_K$ anomalies, using simplified limits from ATLAS and CMS to connect collider searches with B-decay anomalies, and assesses the current and future sensitivity of resonance searches.

## Contribution

It introduces the use of the simplified limits variable $$ to relate collider resonance searches with B-decay anomalies in minimal $Z'$ models.

## Key findings

- High-mass resonance searches are becoming sensitive to $Z'$ explanations.
- Future collider results will provide more stringent tests of these models.
- Current data already constrains some $Z'$ parameter space.

## Abstract

The LHCb collaboration has recently reported a 2.5 $\sigma$ discrepancy with respect to the predicted value in a test of lepton universality in the ratio $R_{K^*}= \hbox{BR}(B \to K^* \mu^+ \mu^-) / \hbox{BR}(B \to K^* e^+ e^-)$. Coupled with an earlier observation of a similar anomaly in $R_{K}$, this has generated significant excitement. A number of new physics scenarios have been proposed to explain the anomaly. In this work we consider simplified limits on $Z'$ models from ATLAS and CMS searches for new resonances in dilepton and dijet modes, and we use the simplified limits variable $\zeta$ to correlate the results of the resonance and B-decay experiments. By examining minimal $Z'$ models that can accomodate the observed LHCb results, we show that the high-mass resonance search results are begining to be sensitive to these models and that future results will be more informative.