Measurement of B_s mixing phase at CDF

TL;DR

This paper reports improved measurements of the CP-violating phase and decay-width difference in the B_s^0 meson system using a large dataset and enhanced analysis techniques at the CDF experiment.

Contribution

It introduces a more precise measurement of B_s mixing parameters with increased data and improved analysis methods, including data-driven flavor-tagging calibration.

Findings

Enhanced bounds on _s^J/ phase and decay-width difference.

Utilized 6500 B_s^0 _j/ decays with 5.2 fb-1 data.

Implemented improved analysis techniques and calibration methods.

Abstract

We present improved bounds on the CP-violating phase \beta_s^{\Jpsi\phi} and on the decay-width difference \Delta\Gamma of the neutral B_s^0 meson system obtained by the CDF experiment at the Tevatron collider . We use 6500 B_s^0 --> J/psi phi decays collected by the dimuon trigger and reconstructed in a sample corresponding to integrated luminosity of 5.2 fb-1. Besides exploiting a two-fold increase in statistics with respect to the previous measurement, several improvements have been introduced in the analysis including a fully data-driven flavour-tagging calibration and proper treatment of possible S-wave contributions.