5,179 research outputs found

    Charmless B(s)VVB_{(s)}\to VV Decays in Factorization-Assisted Topological-Amplitude Approach

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    Within the factorization-assisted topological-amplitude approach, we studied the 33 charmless B(s)VVB_{(s)} \to VV decays, where VV stands for a light vector meson. According to the flavor flows, the amplitude of each process can be decomposed into 8 different topologies. In contrast to the conventional flavor diagrammatic approach, we further factorize each topological amplitude into decay constant, form factors and unknown universal parameters. By χ2\chi^2 fitting 46 experimental observables, we extracted 10 theoretical parameters with χ2\chi^2 per degree of freedom around 2. Using the fitted parameters, we calculated the branching fractions, polarization fractions, CP asymmetries and relative phases between polarization amplitudes of each decay mode. The decay channels dominated by tree diagram have large branching fractions and large longitudinal polarization fraction. The branching fractions and longitudinal polarization fractions of color-suppressed decays become smaller. Current experimental data of large transverse polarization fractions in the penguin dominant decay channels can be explained by only one transverse amplitude of penguin annihilation diagram. Our predictions of those not yet measured channels can be tested in the ongoing LHCb experiment and the Belle-II experiment in future.Comment: 22 pages, 2 figure

    Direct CP violation in τ±K±ρ0(ω)ντK±π+πντ\tau^\pm\rightarrow K^\pm \rho^0 (\omega)\nu_\tau \rightarrow K^\pm \pi^+\pi^-\nu_\tau

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    We study the direct CP violation in the τ±K±ρ0(ω)ντK±π+πντ\tau^\pm\rightarrow K^\pm \rho^0 (\omega)\nu_\tau \rightarrow K^\pm \pi^+\pi^-\nu_\tau decay process in the Standard Model. An interesting mechanism involving the charge symmetry violating mixing between ρ0\rho^0 and ω\omega is applied to enlarge the CP asymmetry. With this mechanism, the maximum differential and localized integrated CP asymmetries can reach (5.61.7+2.9)×1012-(5.6^{+2.9}_{-1.7})\times10^{-12} and 6.33.3+2.4×10116.3^{+2.4}_{-3.3}\times 10^{-11}, respectively, which still leave plenty room for CP-violating New Physics to be discovered through this process

    B-meson Semi-inclusive Decay to 2+2^{-+} Charmonium in NRQCD and X(3872)

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    The semi-inclusive B-meson decay into spin-singlet D-wave 2+2^{-+} charmonium, Bηc2+XB\to \eta_{c2}+X, is studied in nonrelativistic QCD (NRQCD). Both color-singlet and color-octet contributions are calculated at next-to-leading order (NLO) in the strong coupling constant αs\alpha_s. The non-perturbative long-distance matrix elements are evaluated using operator evolution equations. It is found that the color-singlet 1D2^1D_2 contribution is tiny, while the color-octet channels make dominant contributions. The estimated branching ratio B(Bηc2+X)B(B\to \eta_{c2}+X) is about 0.41×1040.41\,\times10^{-4} in the Naive Dimensional Regularization (NDR) scheme and 1.24×1041.24\,\times10^{-4} in the t'Hooft-Veltman (HV) scheme, with renormalization scale μ=mb=4.8\mu=m_b=4.8\,GeV. The scheme-sensitivity of these numerical results is due to cancelation between 1S0[8]{}^1S_0^{[8]} and 1P1[8]{}^1P_1^{[8]} contributions. The μ\mu-dependence curves of NLO branching ratios in both schemes are also shown, with μ\mu varying from mb2\frac{m_b}{2} to 2mb2m_b and the NRQCD factorization or renormalization scale μΛ\mu_{\Lambda} taken to be 2mc2m_c. Comparison of the estimated branching ratio of Bηc2+XB\to \eta_{c2}+X with the observed branching ratio of BX(3872)+KB \to X(3872)+K may lead to the conclusion that X(3872) is unlikely to be the 2+2^{-+} charmonium state ηc2\eta_{c2}.Comment: Version published in PRD, references added, 26 pages, 9 figure

    Discussion on surgical treatment for young patients with congenital lower eyelid entropion

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    AIM: To explore the surgical methods and clinical effects on young patients with congenital lower eyelid entropion. <p>METHODS: There were 27 patients(45 cases)who suffered congenital lower eyelid entropion accepted the modified blepharosphincterectomy. The clinical effects and complications were evaluated.<p>RESULTS: After followed up for 6mo, 42 eyes were fully recovered, 3 eyes were unsuccessful and the cure rate was 93%, 5 eyes suffered minor lower eyelid skin folds, none had lower eyelid retraction and ectropion.<p>CONCLUSION: Modified blepharosphincterectomy is an ideal cosmetic surgical treatment for young patients with congenital lower eyelid entropion. It is an effective surgical treatment with fewer complications

    Constructing Confidence Intervals for Effect Sizes in ANOVA Designs

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    A confidence interval for effect sizes provides a range of plausible population effect sizes (ES) that are consistent with data. This article defines an ES as a standardized linear contrast of means. The noncentral method, Bonett’s method, and the bias-corrected and accelerated bootstrap method are illustrated for constructing the confidence interval for such an effect size. Results obtained from the three methods are discussed and interpretations of results are offered

    Handling Missing Data in Single-Case Studies

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    Multiple imputation is illustrated for dealing with missing data in a published SCED study. Results were compared to those obtained from available data. Merits and issues of implementation are discussed. Recommendations are offered on primal/advanced readings, statistical software, and future research
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