2,792 research outputs found

    Precision Tests of Flavor and CP violation in B Decays

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    Isospin and flavor SU(3) set stringent bounds on penguin pollution in B0(t)ρ+ρB^0(t)\to \rho^+\rho^-, providing a theoretically precise determination of αϕ2\alpha\equiv \phi_2 , α=(91±7exp±3th)\alpha = (91\pm 7_{\rm exp}\pm 3_{\rm th})^\circ. Isospin breaking in a sum rule for BKπB\to K\pi rates is shown to be suppressed. A similar sum rule holds for CP asymmetries in BKπB\to K\pi. Violation of these sum rules would be evidence for an anomalous ΔI=1\Delta I=1 piece in Heff{\cal H}_{\rm eff}.Comment: Reference added; Invited talk presented at the First Workshop on Theory, Phenomenology and Experiments in Heavy Flavor Physics, Anacapri, Italy, 29-31 200

    Implications for CP asymmetries of improved data on BK0π0B \to K^0 \pi^0

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    The decay B0K0π0B^0 \to K^0 \pi^0, dominated by a bsb \to s penguin amplitude, holds the potential for exhibiting new physics in this amplitude. In the pure QCD penguin limit one expects \ckp = 0 and \skp = \sin 2 \beta for the coefficients of cosΔmt\cos \Delta m t and sinΔmt\sin \Delta m t in the time-dependent CP asymmetry. Small non-penguin contributions lead to corrections to these expressions which are calculated in terms of isospin-related BKπB\to K\pi rates and asymmetries, using information about strong phases from experiment. We study the prospects for incisive tests of the Standard Model through examination of these corrections. We update a prediction \ckp=0.15\pm 0.04, pointing out the sensitivity of a prediction \skp\approx 1 to the measured branching ratio for B0K0π0B^0\to K^0\pi^0 and to other observables.Comment: Note added, to be published in Physics Letters

    Suppression of flavor symmetry breaking in B decay sum rules

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    While flavor symmetries are useful for studying hadronic B decays, symmetry relations for amplitudes and decay rates are usually violated by first order symmetry breaking corrections. We point out two cases in which first order symmetry breaking is suppressed by a small ratio of amplitudes: (1) An isospin sum rule for four BKπB\to K\pi decays, where isospin breaking is shown to be negligible. (2) An SU(3) sum rule for pairs of BKπB\to K\pi and BKη8B\to K\eta_8, generalized to pairs of BKπ,BKηB\to K\pi, B\to K\eta and BKηB\to K\eta'.Comment: 11 pages, small corrections, one reference added, submitted to Physics Letters

    CP violation in B meson decays

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    Recent CP asymmetry measurements in tree-dominated processes, B0π+π,ρ+ρ,ρ±π,B+DK+B^0\to \pi^+\pi^-, \rho^+\rho^-, \rho^{\pm}\pi^{\mp}, B^+\to DK^+, and in penguin-dominated decays, Bπ0KS,ηKS,ϕKSB \to \pi^0 K_S, \eta' K_S, \phi K_S, are interpreted in the framework of the Kobayashi-Maskawa (KM) mechanism of CP violation. The KM phase emerges as the dominant source of CP violation in tree-dominated decays, which are beginning to constrain the unitarity triangle beyond other constraints. Improving precision of CP asymmetry measurements in penguin-dominated decays may indicate the need for new physics.Comment: Talk presented at the Sixth International Conference on Hyperons, Charm and Beauty Hadrons, IIT, Chicago, June 27--July 3 200

    CKM Phases from CP Asymmetries

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    Measuring phases in the Cabibbo-Kobayashi-Maskawa matrix through CP asymmetries in B decays is a major goal of current and future experiments. Methods based on charge-conjugation and isospin symmetries involve very little theoretical uncertainties, while schemes based on flavor SU(3) involve uncertainties due to SU(3) breaking. Resolving these uncertainties requires further studies involving a dialogue between theory and experiments.Comment: minor corrections, several references added and update

    Diagnostic for new physics in BπKB \to \pi K decays

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    A recent analysis of BπKB \to \pi K decays concludes that present data do not clearly indicate whether (i) the standard model (or ΔI=0\Delta I=0 new physics) is sufficient, or (ii) ΔI=1\Delta I=1 new physics is needed. We show that these two possibilities can be distinguished by whether a sum rule relating the CP asymmetries of the four BπKB \to \pi K decays is valid. If case (i) is favored, the sum rule holds, and one predicts ACP(π0K0)=0.15A_{CP}(\pi^0 K^0) = -0.15, while in case (ii) fits to new physics involving large values of a color-suppressed tree amplitude entail ACP(π0K0)=0.03A_{CP}(\pi^0 K^0) = -0.03. The current experimental average ACP(π0K0)=0.01±0.10A_{CP}(\pi^0 K^0) = -0.01 \pm 0.10 must be measured a factor of at least three times more precisely in order to distinguish between the two cases.Comment: 10 pages, no figures. Submitted to Physics Letters B. Slight clarification adde

    CP Violation in B Decays: The Standard Model and Beyond

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    We review the subject of CP violation in BB decays in the Standard Model (SM) and beyond the SM. We describe some of the present most promising ways of testing the Cabibbo-Kobayashi-Maskawa (CKM) origin of CP violation through a determination of the three angles of the CKM matrix unitarity triangle. Other sources of CP nonconservation violate SM constraints on the unitarity triangle. We show that different models of physics beyond the SM can be distinguished by combining their effects in CP asymmetries and in rare flavor-changing BB decays.Comment: 19 page

    Penguins, Trees and Final State Interactions in B Decays in Broken SU3

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    The availability of data on BsB_s decays to strange quasi-two-body final states, either with or without charmonium opens new possibilities for understanding different contributions of weak diagrams and in particular the relative contributions of tree and penguin diagrams. Corresponding BdB_d and BsB_s decays to charge conjugate final states are equal in the SU(3) symmetry limit and the dominant SU(3) breaking mechanism is given by ratios of CKM matrix elements. Final State Interactions effects should be small, because strong interactions conserve CC and should tend to cancel in ratios between charge conjugate states. Particularly interesting implications of decays into final states containing η\eta and η\eta' are discussed.Comment: special macro - phyzz

    The Role of BsKπB_s \to K \pi in Determining the Weak Phase γ\gamma

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    The decay rates for B0K+πB^0 \to K^+ \pi^-, B+K0π+B^+ \to K^0 \pi^+, and the charge-conjugate processes were found to provide information on the weak phase γArg(Vub)\gamma \equiv {\rm Arg}(V_{ub}^*) when the ratio rr of weak tree and penguin amplitudes was taken from data on BππB \to \pi \pi or semileptonic BπB \to \pi decays. We show here that the rates for BsKπ+B_s \to K^- \pi^+ and BˉsK+π\bar B_s \to K^+ \pi^- can provide the necessary information on rr, and estimate the statistical accuracy of forthcoming measurements at the Fermilab Tevatron.Comment: 8 pages, LaTeX, no figures, submitted to Physics Letters B, corrections to discussion of SU(3) breaking adde

    Implications of CP Asymmetries in Bπ+πB \to \pi^+ \pi^-

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    CP asymmetries in B0(t)π+πB^0(t)\to \pi^+ \pi^- are studied by relating this process in broken flavor SU(3) with B+K0π+B^+\to K^0\pi^+ and B0K+πB^0\to K^+\pi^-. Using two different scenarios for SU(3) breaking, we show that the range of values of the weak phase α\alpha permitted by the measured asymmetries overlaps with that obtained from other CKM constraints, supporting the KM origin of the asymmetries. We evaluate the potential precision of this method to improve the determination of α\alpha.Comment: 10 pages, 2 figures. To be submitted to Phys. Lett. B. Minor addition
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