First measurement of time-dependent CP violation in \( B_s^0\to {K^{+}}{K^{-}} \) decays

Abstract

Direct and mixing-induced CP-violating asymmetries in \( B_s^0\to {K^{+}}{K^{-}} \) decays are measured for the first time using a data sample of pp collisions, corresponding to an integrated luminosity of 1.0 fb−1, collected with the LHCb detector at a centre-of-mass energy of 7 TeV. The results are C KK  = 0.14 ± 0.11 ± 0.03 and S KK  = 0.30 ± 0.12 ± 0.04, where the first uncertainties are statistical and the second systematic. The corresponding quantities are also determined for B 0π + π decays to be C ππ  = −0.38 ± 0.15 ± 0.02 and S ππ  = −0.71 ± 0.13 ± 0.02, in good agreement with existing measurements.

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