Measurements of Lifetimes, Mixing and CP Violation of B Mesons with the BaBar Detector

TL;DR

This paper reports measurements of B meson lifetimes, mixing parameters, and CP violation using data from the BaBar detector, providing results consistent with the Standard Model and improving precision in these fundamental parameters.

Contribution

First measurement of sin(2 beta) and B meson parameters using BaBar data, with improved accuracy and confirmation of Standard Model predictions.

Findings

Measured sin(2 beta) = 0.75 ± 0.09 (stat) ± 0.04 (syst)

B lifetimes and oscillation frequency eltamd are precisely determined

Results are consistent with Standard Model expectations

Abstract

Using a data sample of 62 million \FourS\to B\Bbar decays collected between 1999 and 2001 by the BaBar detector at the PEP2 asymmetric-energy B Factory at SLAC we study events in which one neutral B meson is fully reconstructed in a final state containing a charmonium meson and the flavour of the other neutral B meson is determined from its decay products. The amplitude of the CP-violating asymmetry, which in the Standard Model is proportional to sin(2 beta), is derived from the decay time distributions. We measure sin(2 beta) = 0.75 \pm 0.09 (stat) \pm 0.04 (syst) and |\lambda| = 0.92 \pm 0.06 (stat) \pm 0.02 (syst). The latter is consistent with the Standard Model expectation of no direct CP violation. These results are preliminary. In addition, we report on precision measurements of the B lifetimes, and the \Bz-\Bzb oscillation frequency \deltamd.