1,509 research outputs found

    Newly observed two-body decays of B mesons in a hybrid perspective

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    In consistency with the b --> c type of (quasi) two body decays, recently observed two body decays of B mesons are studied in a hybrid perspective in which their amplitude is given by a sum of factorizable and non-factorizable ones, and a role of the latter in these decays are discussed.Comment: 7 page

    Lifetime Difference and Endpoint effect in the Inclusive Bottom Hadron Decays

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    The lifetime differences of bottom hadrons are known to be properly explained within the framework of heavy quark effective field theory(HQEFT) of QCD via the inverse expansion of the dressed heavy quark mass. In general, the spectrum around the endpoint region is not well behaved due to the invalidity of 1/mQ1/m_Q expansion near the endpoint. The curve fitting method is adopted to treat the endpoint behavior. It turns out that the endpoint effects are truly small and the explanation on the lifetime differences in the HQEFT of QCD is then well justified. The inclusion of the endpoint effects makes the prediction on the lifetime differences and the extraction on the CKM matrix element ∣Vcb∣|V_{cb}| more reliable.Comment: 11 pages, Revtex, 10 figures, 6 tables, published versio

    Hadronic decays of B involving a tensor meson through a b→cb \to c transition

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    We re-analyze hadronic decays of B mesons to a pseudoscalar (P) and a tensor meson (T), or a vector meson (V) and a tensor meson, through a b→cb \to c transition. We discuss possible large uncertainties to branching ratios (BR's) of the relevant modes, mainly arising from uncertainties to the hadronic form factors for the B→TB \to T transition. The BR's and CP asymmetries for B→PTB \to PT and VT decays are then calculated by using the form factors given in the ISGW2 model (the improved version of the original Isgur-Scora-Grinstein-Wise (ISGW) model). We find that the estimated BR's of many modes are increased by an order of magnitude, compared to the previous results calculated within the ISGW model.Comment: 22 pages, LaTex; minor clarifications included; to appear in Phys. Rev.

    Measuring the Photon Helicity in Radiative B Decays

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    We propose a way of measuring the photon polarization in radiative B decays into K resonance states decaying to K\pi\pi, which can test the Standard Model and probe new physics. The photon polarization is shown to be measured by the up-down asymmetry of the photon direction relative to the K\pi\pi decay plane in the K resonance rest frame. The integrated asymmetry in K_1(1400)\to K\pi\pi, calculated to be 0.34\pm 0.05 in the Standard Model, is measurable at currently operating B factories.Comment: 4 pages, final version to appear in Physical Review Letter

    Understanding the newly observed Y(4008) by Belle

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    Very recently a new enhancement around 4.05 GeV was observed by Belle experiment. In this short note, we discuss some possible assignments for this enhancement, i.e. ψ(3S)\psi(3S) and D∗Dˉ∗D^*\bar{D}^* molecular state. In these two assignments, Y(4008) can decay into J/ψπ0π0J/\psi\pi^0\pi^0 with comparable branching ratio with that of Y(4008)→J/ψπ+π−Y(4008)\to J/\psi\pi^+\pi^-. Thus one suggests high energy experimentalists to look for Y(4008) in J/ψπ0π0J/\psi\pi^0\pi^0 channel. Furthermore one proposes further experiments to search missing channel DDˉD\bar{D}, DDˉ∗+h.c.D\bar{D}^*+h.c. and especially χcJπ+π−π0\chi_{cJ}\pi^+\pi^-\pi^0 and ηcπ+π−π0\eta_c\pi^+\pi^-\pi^0, which will be helpful to distinguish ψ(3S)\psi(3S) and D∗Dˉ∗D^*\bar{D}^* molecular state assignments for this new enhancement.Comment: 4 pages, 5 figures. Typos correcte

    Supersymmetric Effects on Isospin Symmetry Breaking and Direct CP Violation in Bâ†’ÏÎłB \to \rho \gamma

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    We argue that one can search for physics beyond the standard model through measurements of the isospin-violating quantity Δ−0≡Γ(Bâˆ’â†’Ïâˆ’Îł)/2Γ(B0→ρ0Îł)−1\Delta^{-0} \equiv \Gamma(B^- \to \rho^- \gamma)/2\Gamma(B^0 \to \rho^0 \gamma)-1, its charge conjugate Δ+0\Delta^{+0}, and direct CP violation in the partial decay rates of BÂ±â†’ÏÂ±ÎłB^\pm \to \rho^\pm \gamma. We illustrate this by working out theoretical profiles of the charge-conjugate averaged ratio Δ≡12(Δ+0+Δ−0)\Delta \equiv {1 \over 2}(\Delta^{+0} +\Delta^{-0}) and the CP asymmetry ACP(BÂ±â†’ÏÂ±Îł)A_{CP}(B^\pm \to \rho^\pm \gamma) in the standard model and in some variants of the minimal supersymmetric standard model. We find that chargino contributions in the large tan⁥ÎČ\tan \beta region may modify the magnitudes and flip the signs of Δ\Delta and ACP(BÂ±â†’ÏÂ±Îł)A_{CP}(B^\pm \to \rho^\pm \gamma) compared to their standard-model values, providing an unmistakeable signature of supersymmetry.Comment: 10 pages, 7 figures (requires graphicx

    QCD-based description of one-particle inclusive B decays

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    We discuss one-particle inclusive B decays in the limit of heavy b and c quarks. Using the large-N_C limit we factorize the non-leptonic matrix elements, and we employ a short distance expansion. Modeling the remaining nonperturbative matrix elements we obtain predictions for various decay channels and compare them with existing data.Comment: LaTeX, 22 pages, 6 figures (eps); analytical and numerical results unchanged, misrepresentation of experimental data in Fig. 5 corrected, final published versio

    Heavy Baryon Production and Decay

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    The branching ratio B(Lambda_c -> p K- pi+) normalizes the production and decay of charmed and bottom baryons. At present, this crucial branching ratio is extracted dominantly from B.bar -> baryons analyses. This note questions several of the underlying assumptions and predicts sizable B.bar -> D(*) N N'.bar X transitions, which were traditionally neglected. It predicts B(Lambda_c -> p K- pi+) to be significantly larger (0.07 +/- 0.02) than the world average. Some consequences are briefly mentioned. Several techniques to measure B(Lambda_c -> p K- pi+) are outlined with existing or soon available data samples. By equating two recent CLEO results, an appendix obtains B(D0 -> K- pi+)= 0.035 +/- 0.002, which is somewhat smaller than the current world average.Comment: 27 pages, 4 eps figures, revte

    Implications of Recent Bˉ0→D(∗)0X0\bar{B}^0\to D^{(*)0}X^0 Measurements

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    The recent measurements of the color-suppressed modes Bˉ0→D(∗)0π0\bar B^0\to D^{(*)0}\pi^0 imply non-vanishing relative final-state interaction (FSI) phases among various Bˉ→Dπ\bar B\to D\pi decay amplitudes. Depending on whether or not FSIs are implemented in the topological quark-diagram amplitudes, two solutions for the parameters a1a_1 and a2a_2 are extracted from data using various form-factor models. It is found that a2a_2 is not universal: ∣a2(Dπ)∣=0.40−0.55|a_2(D\pi)|= 0.40-0.55 and ∣a2(D∗π)∣=0.25−0.35|a_2(D^*\pi)|= 0.25-0.35 with a relative phase of order (50−55)∘(50-55)^\circ between a1a_1 and a2a_2. If FSIs are not included in quark-diagram amplitudes from the outset, a2eff/a1effa_2^{eff}/a_1^{eff} and a2effa_2^{eff} will become smaller. The large value of ∣a2(Dπ)∣|a_2(D\pi)| compared to ∣a2eff(Dπ)∣|a_2^{eff}(D\pi)| or naive expectation implies the importance of long-distance FSI contributions to color-suppressed internal WW-emission via final-state rescatterings of the color-allowed tree amplitude.Comment: 17 pages. The Introduction is substantially revised and the order of the presentation in Sec. 2 is rearranged. To appear in Phys. Re

    Tau and Charm physics highlights

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    In tau physics, we are at the frontier between the completion of the LEP program and the start of analyses from b-factories, which are expected to produce results in the coming years. Nice results from CLEO are steadily delivered in the meantime. For charm, impressive progress have been achieved by fixed target experiments in the search for CP violation and D^0 - \bar D^0 oscillations. First results from b-factories demonstrate the power of these facilities in such areas. The novel measurement of the D* width by CLEO happens to be rather different from current expectations. The absence of a charm factory explains the lack or the very slow progress in the absolute scale determinations for charm decays.Comment: "Typos corrected and references added
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