3,593 research outputs found

    Three-body Baryonic anti-B -->Lambda anti-p pi Decays and Such

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    We study decay rates and spectra of anti-B --> Lambda anti-p pi, Sigma0 anti-p pi, Sigma- anti-n pi, Xi0 anti-Sigma+ pi, Xi- anti-Sigma0 pi and Xi- anti-Lambda pi modes under a factorization approach. The baryon pairs are produced through vector, axial vector, scalar and pseudoscalar operators. Previous predictions, including ours, are an order of magnitude too small compared to experiment. By incorporating QCD counting rules and studying the asymptotic behavior, we find an earlier relation between the pseudoscalar and axial vector form factors to be too restrictive. Instead, the pseudoscalar and scalar form factors are related asymptotically. Following this approach, the measured Lambda anti-p pi rate (~4.0x10^{-6}) and spectrum can be understood, and Lambda should be dominantly left-hand polarized, while we expect Br(Sigma0 anti-p pi)~1.6x10^{-6}. These results and other predictions can be checked soon.Comment: 18 pages, 3 figures; use updated Belle results, add Lambda polarization stud

    Supersymmetric Model Contributions to Bd0B^0_d--Bˉd0\bar B^0_d Mixing and Bππ,ργB\to\pi\pi,\rho\gamma Decays

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    Recent results from Belle and BaBar Collaborations hint at a small sin2ϕ1\sin2\phi_1, while the measured BππB\to\pi\pi rate also seems to be on the low side. Supersymmetric (SUSY) models with down squark mixings can account for the deficits in both cases. By studying the origin of SUSY contributions that could impact on Bd0B^0_d--Bˉd0\bar B^0_d mixing and BππB\to\pi\pi decay, we find that the former would most likely arise from left-left or right-right squark mixings, while the latter would come from left-right squark mixings. These two processes in general are not much correlated in the Minimum Supersymmetric Standard Model. If the smallness of BππB\to\pi\pi is due to SUSY models, one would likely have large BργB\to\rho\gamma from chiral enhancement, and the rate could be within present experimental reach. Even if BργB\to\rho\gamma is not greatly enhanced, it could have large mixing dependent CP violation.Comment: 10 pages, 6 figures. Version to appear in Eur. Phys. J.

    Indication for Large Rescatterings in Charmless Rare B Decays

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    The current wealth of charmless B decay data may suggest the presence of final state rescattering. In a factorized amplitude approach, better fits are found by incorporating two SU(3) rescattering phase differences, giving delta ~ 65 degree and sigma ~ 90 - 100 degree. Fitting with unitarity phase phi_3 as a fit parameter gives phi_3 ~ 96 degree, the CP asymmetries A_{pi pi}, S_{pi pi} agree better with BaBar, and the sigma phase is slightly lower. Keeping phi_3 = 60 degree fixed in fit gives S_{pi pi} ~-0.9, which agrees better with Belle. With the sizable delta, sigma rescattering phases as fitted, many direct CP asymmetries flip sign, and B0 --> pi0 pi0, K- K+ rates are of order 10^{-6}, which can be tested soon.Comment: 6 pages, 4 figures, updated, references adde

    Identifying the Service Quality for a B2B Cross-Border E-Commerce Platform

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    The global cross-border e-commerce (CBEC) transactions is experiencing a fast development in recent years. However, the academic research is still rare. In addition, service quality of the CBEC platforms have been identified as the important factors of the success of CBEC but there is a lack of empirical work to identify the service quality of the business to business (B2B) CBEC platforms are rare. To fulfill this gap, this study intends to identify the critical service quality of the B2B CBEC platform. Based on the service quality model, we will identify the critical service quality of the B2B CBEC platform. We will conduct a modified Delphi method to collect data with the experts and suppliers in the platform. Our research findings will contribute to the academia by creating a service quality model of B2B CBEC platform. The results will provide practical insights for the platform design of B2B CBEC platform

    Rescattering effects in B_{u,d,s}(bar) to D P, D(bar) P decays

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    We study quasi-elastic rescattering effects in B_{u,d,s}(bar) to DP, D(bar)P decays, where P is a light pseudoscalar. The updated measurements of B_{u,d}(bar) to DP decays are used to extract the effective Wilson coefficients a^{eff}_1 ~ 0.90, a^{eff}_2 ~ 0.23, three strong phases delta ~ 53 degree, theta ~ 18 degree, sigma ~ -88 degree, and the mixing angle tau ~ 9 degree. This information is used to predict rates of nineteen B_{s}(bar) to DP and B_{u,d,s}(bar) to D(bar)P decay modes, including modes of interests in the gamma/phi_3 program. Many decay rates are found to be enhanced. In particular, the B_s(bar) to D0 K0 rate is predicted to be 8\times 10^{-4}, which could be measured soon. The rescattering effects on the corresponding B_{u,d,s}(bar) to D(bar)P, DP amplitude ratios r_B, r_{B_s}, and the relative strong phases delta_B, delta_{B_s} are studied. Although the decay rates are enhanced in most cases, r_{B,B_s} values are similar to factorization expectation.Comment: 16 page

    Development of a Microsoft Excel tool for one-parameter Rasch model of continuous items: an application to a safety attitude survey

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    Abstract Background Many continuous item responses (CIRs) are encountered in healthcare settings, but no one uses item response theory’s (IRT) probabilistic modeling to present graphical presentations for interpreting CIR results. A computer module that is programmed to deal with CIRs is required. To present a computer module, validate it, and verify its usefulness in dealing with CIR data, and then to apply the model to real healthcare data in order to show how the CIR that can be applied to healthcare settings with an example regarding a safety attitude survey. Methods Using Microsoft Excel VBA (Visual Basic for Applications), we designed a computer module that minimizes the residuals and calculates model’s expected scores according to person responses across items. Rasch models based on a Wright map and on KIDMAP were demonstrated to interpret results of the safety attitude survey. Results The author-made CIR module yielded OUTFIT mean square (MNSQ) and person measures equivalent to those yielded by professional Rasch Winsteps software. The probabilistic modeling of the CIR module provides messages that are much more valuable to users and show the CIR advantage over classic test theory. Conclusions Because of advances in computer technology, healthcare users who are familiar to MS Excel can easily apply the study CIR module to deal with continuous variables to benefit comparisons of data with a logistic distribution and model fit statistics
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