Evidence for CP-Violating Asymmetries in B0->pi+pi- Decays and Constraints on the CKM Angle phi2

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dc.creatorBelle Collaboration
dc.creatorAbe, K.
dc.date2003-01-24
dc.date2003-04-03
dc.date.accessioned2026-07-07T12:01:53Z
dc.date.available2026-07-07T12:01:53Z
dc.descriptionWe present an improved measurement of CP-violating asymmetries in B0 -> pi+ pi- decays based on a 78 fb^-1 data sample collected at the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We reconstruct one neutral B meson as a B0 -> pi+ pi- CP eigenstate and identify the flavor of the accompanying B meson from inclusive properties of its decay products. We apply an unbinned maximum likelihood fit to the distribution of the time intervals between the two B meson decay points. The fit yields the CP-violating asymmetry amplitudes Apipi = +0.77+/-0.27(stat)+/-0.08(syst) and Spipi = -1.23+/-0.41(stat)+0.08/-0.07(syst), where the statistical uncertainties are determined from Monte Carlo pseudo-experiments. We obtain confidence intervals for CP-violating asymmetry parameters Apipi and Spipi based on a frequentist approach. We rule out the CP-conserving case, Apipi=Spipi=0, at the 99.93% confidence level. We discuss how these results constrain the value of the CKM angle phi2.
dc.description26 pages, 13 figures, submitted to Phys. Rev. D
dc.identifierhttps://arxiv.org/abs/hep-ex/0301032
dc.identifierhttp://arxiv.org/abs/hep-ex/0301032
dc.identifierPhys.Rev.D68:012001,2003
dc.identifierdoi:10.1103/PhysRevD.68.012001
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/207253
dc.subjectHigh Energy Physics - Experiment
dc.titleEvidence for CP-Violating Asymmetries in B0->pi+pi- Decays and Constraints on the CKM Angle phi2
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