psi pi(+) pi(-)decays (original) (raw)

The time-dependent CP asymmetry in B 0 s ! J=c K þ K À decays is measured using pp collision data at ffiffi ffi s p ¼ 7 TeV, corresponding to an integrated luminosity of 1:0 fb À1 , collected with the LHCb detector. The decay-time distribution is characterized by the decay widths À L and À H of the light and heavy mass eigenstates of the B 0 s-" B 0 s system and by a CP-violating phase s. In a sample of 27 617 B 0 s ! J=c K þ K À decays, where the dominant contribution comes from B 0 s ! J=c decays, these parameters are measured to be s ¼ 0:07 AE 0:09ðstatÞ AE 0:01ðsystÞ rad, À s ðÀ L þ À H Þ=2 ¼ 0:663 AE 0:005ðstatÞ AE 0:006ðsystÞ ps À1 , and ÁÀ s À L À À H ¼ 0:100 AE 0:016ðstatÞ AE 0:003ðsystÞ ps À1 , corresponding to the single most precise determination of s , ÁÀ s , and À s. The result of performing a combined analysis with B 0 s ! J=c þ À decays gives s ¼ 0:01 AE 0:07ðstatÞ AE 0:01ðsystÞ rad, À s ¼ 0:661 AE 0:004ðstatÞ AE 0:006ðsystÞ ps À1 , and ÁÀ s ¼ 0:106 AE 0:011ðstatÞ AE 0:007ðsystÞ ps À1. All measurements are in agreement with the Standard Model predictions.