Belle: Updated results on B -> Kpi/KK decays
نویسنده
چکیده
We report an improved measurements of direct CP violation in the decay B0 → K+π− using 350 fb−1 of data and measurements of B meson decays to two kaons using 253 fb−1 of data. The measured CP violating asymmetries are ACP(Kπ) = −0.113 ± 0.022(stat.)± 0.008(syst.), ACP(Kπ) = 0.04±0.04(stat.)±0.02(syst.) and ACP(ππ) = 0.02±0.08(stat.)±0.01(syst.), where the latter correspond to the intervals −0.03 < ACP(Kπ) < 0.11 and −0.12 < ACP(ππ) < 0.15 at 90% confidence level. We also find evidence for signals in B+ → K 0 K+ and B0 → K0K with significances of 3.0σ and 3.5σ , respectively. (Charge-conjugate modes included) The corresponding branching fractions are measured to be B(B+ → KK+) = (1.0± 0.4± 0.1)× 10−6 and B(B0 → K0K) = (0.8± 0.3± 0.1)× 10−6. No signal is observed in the decay B0 → K+K− and we set an upper limit of 3.7×10−7 at 90% confidence level. These results are obtained from a data sample collected near the Υ(4S) resonance, with the Belle detector at the KEKB asymmetric energy e+e− collider.
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