ISSN - 00319007, EISSN - 10797114, Physical Review Letters, 2007, vol. 99, p. -
Search for the CP-violating decays Υ(4S)→B0B̄0→J/ ψKS0+J/ψ(ηc)KS0
We report the first search for CP-violating decays of the Υ(4S) using a data sample that contains 535×106 Υ(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 4×10-7 at the 90% confidence level for the branching fractions of the CP violating modes, Υ(4S)→B0B̄0→J/ψKS0+J/ψ(ηc)KS0. Extrapolating the result, we find that an observation with 5σ significance is expected with a 30ab-1 data sample, which is within the reach of a future super B factory. © 2007 The American Physical Society.