Measurement of the CP-violation parameter sin(2beta) in B0 to J/psi-Kshort decays

Abstract

A sample of 400 $B^0_d/\bar{B}{^0_d} \to J/\psi K^0_s$ decays collected in $\bar{p}p$ collisions by the CDF detector is used to directly measure the CP-violation parameter $\sin(2\beta)$. We find $\sin(2\beta) = 0.79 ^{+0.41}_{-0.44}$,favoring the standard model expectation of a large $CP$ violation in this $B^0$ decay mode.