Search for CP Violation in B0s to J/psi phi at CDF

TL;DR

This paper reports a search for CP violation in B0s to J/psi phi decays using CDF data, finding results close to but slightly deviating from the standard model prediction, with about 2000 events analyzed.

Contribution

First measurement of CP violation parameters in B0s to J/psi phi decays at CDF with 1.5 sigma deviation from standard model.

Findings

Approximately 2000 signal events reconstructed.

Confidence region in CP phase and width difference parameters.

Result is 1.5 sigma from the standard model prediction.

Abstract

The CKM mechanism is well established as the dominant mechanism for $CP$ violation, which was first discovered in the neutral kaons in 1964 \cite{ref:cpkaon}. To search for new sources of CP violation, one can exploit a handful of systems in which the standard model makes a precise prediction of CP violation. In the $B^0_s\to J/\psi \phi$ system, CP violation in the interference of mixing and decay is precisely predicted in the standard model, the prediction being very close to zero. The CDF experiment reconstructs about 2000 signal events in 1.35 fb$^{-1}$ of luminosity. We obtain a confidence region in the space of the parameters $\beta_s$, the CP phase, and $\Delta\Gamma$, the width difference. This result is 1.5 $\sigma$ from the standard model prediction.