Search for the CP-violating decays ${\rm Y}(4S)B0\bar{B}0J/K{0}_S+J/\psi ({\eta }_c)K{0}_S$

Abstract

We report the first search for CP violating decays of the ${\rm Y}(4S)$ using a data sample that contains 535 million ${\rm Y}(4S)$ mesons with the Belle detector at the KEKB asymmetric-energy e^+ e^- collider. A partial reconstruction technique is employed to enhance the signal sensitivity. No significant signals were observed. We obtain an upper limit of $4\times 10^{-7}$ at the 90 % confidence level for the branching fractions of the $CP$ violating modes, ${\rm Y}(4S)\to B^0{\bar{B}}^0\to J/\psi K_S^0+J/\psi ({\eta }_c)K_S^0$. Extrapolating the result, we find that an observation with 5$\sigma$ significance is expected with a 30 ab^{-1} data sample, which is within the reach of a future super B factory.

Submitted to PRL

References in corpus (3)

• Big-Bang nucleosynthesis (Particle Data Group mini-review)
• The Cosmological Parameters 2006
• Neutral B Flavor Tagging for the Measurement of Mixing-induced CP Violation at Belle