# Search for $CP$ violation in $B^0_s$ mixing at LHCb

## TL;DR

This paper reports a precise measurement of the $CP$ violating phase $\,phi_s$ in $B_s^0$ mixing at LHCb, testing the Standard Model prediction and searching for signs of new physics.

## Contribution

It presents the most precise single measurement of $\,phi_s$ using $B_s^0
ightarrow J/\,psi K^+K^-$ data and combines it with other results for a comprehensive analysis.

## Key findings

- Measured $\,phi_s$ consistent with Standard Model predictions.
- Combined results improve the precision of $\,phi_s$ measurement.
- No evidence of new physics observed in $B_s^0$ mixing.

## Abstract

One of the main goals of the LHCb experiment is to determine the mixing-induced $CP$ violating phase $\phi_s$ in $b \rightarrow c\bar{c}s$ transitions. Assuming the Standard Model, $\phi_s$ is precisely predicted, hence new physics could easily affect the measurement. The most precise single measurement using $B^0_s \rightarrow J/\psi K^+K^-$ data collected in 2015 and 2016 is presented along with a total combined value including all LHCb $\phi_s^{c\bar{c}s}$ analyses. The result is further combined with Tevatron and other LHC experimental results.