Measurement of CP Asymmetries and Branching Fractions in B0 -> pi+ pi-, B0 -> K+ pi-, B0 -> pi0 pi0, B0 -> K0 pi0 and Isospin Analysis of B -> pi pi Decays
The BABAR Collaboration, B. Aubert
备注:
27 pages, 23 postscript figures, submitted to ICHEP 2008. Update references and the quoted Kspi0 sum-rule value
我们提出了在衰变B 0-> pi+ pi-,B 0-> K+ pi-,B 0-> pi 0 pi 0和B 0-> K 0 pi 0中CP破坏不对称性和分支分数的改进测量的初步结果。此更新包括在SLAC的非对称PEP-II B介子工厂的BaBar实验在Y(4S)共振处获得的所有数据,对应于4.67 +- 5百万个BBbar对。我们发现Spipi = -0.68 +-0.10 +-0.03,Cpipi = -0.25 +-0.08 +-0.02,AKpi = -0.107 +-0.016 +0.006-0.004,Cpi 0 pi 0 = -0.43 +-0.26 +-0.05,BF(B 0-> pi 0 pi 0)=(1.83 +- 0.21 +- 0.13)x 10^-6,BF(B 0-> K 0 pi 0)=(10.1 +- 0.6 +- 0.4)x 10^-6,其中第一个误差是统计误差,第二个误差是系统误差。我们观察到CP破坏,在B 0-> pi+ pi-中显著性为6.7 sigma,在B 0-> K+ pi-中显著性为6.1 sigma。对幺正三角角α的约束由所有B -> pipi速率和不对称性之间的同位旋关系确定。
英文摘要:
We present preliminary results of improved measurements of the CP-violating asymmetries and branching fractions in the decays B0 -> pi+ pi-, B0 -> K+ pi-, B0 -> pi0 pi0, and B0 -> K0 pi0. This update includes all data taken at the Y(4S) resonance by the BaBar experiment at the asymmetric PEP-II B-meson factory at SLAC, corresponding to 467 +- 5 million BBbar pairs. We find
Spipi = -0.68 +- 0.10 +- 0.03,
Cpipi = -0.25 +- 0.08 +- 0.02,
AKpi = -0.107 +- 0.016 +0.006-0.004,
Cpi0pi0 = -0.43 +- 0.26 +- 0.05,
BF(B0 -> pi0 pi0) = (1.83 +- 0.21 +- 0.13) x 10^-6, BF(B0 -> K0 pi0) = (10.1 +- 0.6 +- 0.4) x 10^-6, where the first error is statistical and the second is systematic. We observe CP violation with a significance of 6.7 sigma in B0 -> pi+ pi- and 6.1 sigma in B0 -> K+ pi-. Constraints on the Unitarity Triangle angle alpha are determined from the isospin relation between all B -> pipi rates and asymmetries.
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Improved Measurements of Branching Fractions and CP Asymmetries in B-> eta h Decays
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Improved Measurements of Branching Fractions and CP Asymmetries in B-> eta h Decays
We report improved measurements of B decays with an eta meson in the final state using 492 fb^{-1} of data collected by the Belle detector at the KEKB e^+ e^- collider. We observe the decays B^{+-}-> eta pi^{+-} and B^{+-}-> eta K^{+-}; the measured branching fractions are Br(B^{+-}-> eta pi^{+-}) = (4.2+- 0.4(stat)+- 0.2(sys))x10^{-6} and Br(B^{+-}-> eta K^{+-}) = (1.9+-0.3(stat)^{+0.2}_{-0.1}(sys))x10^{-6}. The corresponding CP-violating asymmetries are measured to be -0.23+- 0.09(stat) +-0.02(sys) for eta pi^{+-} and -0.39+-0.16(stat)+-0.03(sys) for eta K^{+-}. We also search for B^0-> eta …
Measurements of Branching Fractions and CP Asymmetries in B-> etah Decays
我们利用KEKB e^+ e^-对撞机Belle探测器收集的140 fb^{-1}的数据,测量了B到赝标-赝标衰变,其中至少有一个η介子处于末态。我们观察到B^+-> eta pi^+的衰变,并发现了B^+-> eta K+的证据;测得的分支分数为B(B^+-> eta pi^+)=(4.8^{+0.8}_{-0.7}(stat)+- 0.3(sys))*10^{-6}和B(B^+-> eta K^+)=(2.1 +- 0.6(stat)+- 0.2(sys))*10^{-6}。测得它们对应的CP破坏不对称性,对于eta pi^+-为0.07+- 0.15(stat)+- 0.03(sys),对于eta K^+-为-0.49+- 0.31(stat)+- 0.07(sys)。对于中性B->eta h衰变没有发现显著的信号。我们在90%置信水平下报告了以下分支分数的上限:B(B-> eta K^0 < 2.0* 10^{-6},B(B-> eta pi 0)<2.5*10^{-6}和B(B-> eta eta)<2.0*10^{-6}。
Hadronic $B$ decays without a charm quark constitute a powerful probe to search for physics beyond the standard model as well as to provide constraints on $CP$ violation parameters. We report final measurements from Belle of the branching fractions and $CP$ asymmetries for the decays $B^{0} \rightarrow π^{0} π^{0}$ and $B^{\pm} \rightarrow K^{+} K^{-} π^{\pm}$. The $B^{0} \rightarrow π^{0} π^{0}$ measurements enable us to improve constraints on the angle $ϕ_{2}$ of the CKM unitarity triangle. For $B^{\pm} \rightarrow K^{+} K^{-} π^{\pm}$ we measure $CP$ asymmetry as a function of the invariant…
A study of B^+/- --> J/psi pi^+/- and B^+/- --> J/psi K^+/- decays: measurement of the ratio of branching fractions and search for direct CP-violating charge asymmetries
The approximate symmetry of the strong interactions under isospin transformations is among the most precise tools available to control hadronic matrix elements. It is crucial in extracting fundamental parameters, but also provides avenues for the search of phenomena beyond the Standard Model. The precision of the resulting predictions requires special care when determining the quantities they are to be tested with. Specifically, in the extraction of branching ratios often isospin symmetry is assumed at one point or another implicitly, implying a significant bias for precision analyses. We extr…
Measurement of branching fractions and charge asymmetries in B+ decays to etapi+, etaK+, etarho+ and eta'pi+, and search for B0 decays to etaK0 and etaomega
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Measurement of Branching Fractions and Search for CP-Violating Charge Asymmetries in Charmless Two-Body B Decays into Pions and Kaons
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