Evidence for direct CP violation in B0 ---> K+ pi- decays

Collaboration
Aug, 2004

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Abstract:
We report evidence for direct CP violation in the decay B0 -> K+-pi-+ with 253/fb of data collected with the Belle detector at the KEKB e+e- collider. Using 275 million B B_bar pairs we observe a B -> K+-pi-+ signal with 2140+-53 events. The measured CP violating asymmetry is Acp(K+-pi-+) = -0.101+-0.025 (stat)+-0.005 (syst), corresponding to a significance of 3.9 sigma including systematics. We also search for CP violation in the decays B+- -> K+-pi0 and B+- -> pi+-pi0. The measured CP violating asymmetries are Acp(K+-pi0) = 0.04+-0.05(stat)+-0.02(syst) and Acp(pi+-pi0) = -0.02+-0.10(stat)+-0.01(syst), corresponding to the intervals -0.05 < Acp(K+-pi0) < 0.13 and -0.18
  • 11.30.Er
  • 12.15.Hh
  • 13.25.Hw
  • B mesons
  • CP invariance
  • meson hadronic decay
  • electron positron: colliding beams
  • electron positron: annihilation
  • Upsilon(10570): electroproduction
  • B: pair production