Measurement of the CP-Violation Parameter $\sin(2\beta)$ in $B^0_d/\bar{B}{^0_d} \to J/\psi K^0_S$ Decays

TL;DR

This paper reports a measurement of the CP-violation parameter sin(2β) in B0 decay processes using data from Fermilab's Tevatron, providing insights into matter-antimatter asymmetry within the Standard Model.

Contribution

First measurement of sin(2β) in B0 decays at the Tevatron using a novel flavor tagging technique.

Findings

Measured sin(2β) = 1.8 ± 1.1 (stat) ± 0.3 (syst)

Observed 198 ± 17 B0 decay events

Demonstrated feasibility of time-dependent CP violation measurement at hadron colliders.

Abstract

We present a measurement of the time-dependent asymmetry in the rate for $\bar{B}{^0_d}$ versus $B^0_d$ decays to $J/\psi K^0_S$. In the context of the Standard Model this is interpreted as a measurement of the CP-violation parameter $\sin(2\beta)$. A total of $198\pm 17$ $B^0_d/\bar{B}{^0_d}$ decays were observed in $p\bar{p}$ collisions at $\sqrt{s} = 1.8$ TeV by the CDF detector at the Fermilab Tevatron. The initial $b$-flavor is determined by a same side flavor tagging technique. Our analysis results in $\sin(2\beta) = 1.8\pm 1.1(stat)\pm 0.3(syst)$.