1,220 research outputs found

    L.O.V.E. is the Answer: The Movie

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    The presenter will show a 60-minute, condensed version of their film, “Walking While Black: L.O.V.E. Is The Answer,” followed by a 15-minute question-and-answer of the L.O.V.E. Is The Answer principles that make up the foundation of the film

    Implications of the CP asymmetry in semileptonic B decay

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    Recent experimental searches for ASLA_{SL}, the CP asymmetry in semileptonic B decay, have reached an accuracy of order one percent. Consequently, they give meaningful constraints on new physics. We find that cancellations between the Standard Model (SM) and new physics contributions to B0−Bˉ0B^0 - \bar B^0 mixing cannot be as strong as was allowed prior to these measurements. The predictions for this asymmetry within the SM and within models of minimal flavor violation (MFV) are below the reach of present and near future measurements. Including order mc2/mb2m_c^2/m_b^2 and ΛQCD/mb\Lambda_{QCD}/m_b corrections we obtain the SM prediction: −1.3×10−3<ASL<−0.5×10−3-1.3 \times 10^{-3} < A_{SL} < -0.5 \times 10^{-3}. Future measurements can exclude not only the SM, but MFV as well, if the sign of the asymmetry is opposite to the SM or if it is same-sign but much enhanced. We also comment on the CP asymmetry in semileptonic BsB_s decay, and update the range of the angle ÎČs\beta_s in the SM: 0.026<sin⁥2ÎČs<0.0480.026 < \sin2\beta_s < 0.048.Comment: 16 pages, a sign typo in eq.(11) fixed, to appear in Phys. Rev.

    Implications of the Top Quark Mass Measurement for the CKM Parameters, xsx_s and CP Asymmetries

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    Motivated by the recent determination of the top quark mass by the CDF collaboration, \mt =174 \pm 10 ^{+13}_{-12} GeV, we review and update the constraints on the parameters of the quark flavour mixing matrix VCKMV_{CKM} in the standard model. In performing our fits, we use inputs from the measurements of the following quantities: (i) \abseps, the CP-violating parameter in KK decays, (ii) \delmd, the mass difference due to the \bdbdbar\ mixing, (iii) the matrix elements \absvcb and \absvub, and (iv) BB-hadron lifetimes. We find that the allowed region of the unitarity triangle is very large, mostly due to theoretical uncertainties. (This emphasizes the importance of measurements of CP-violating rate asymmetries in the BB system.) Nevertheless, the present data do somewhat restrict the allowed values of the coupling constant product fBdB^Bdf_{B_d}\sqrt{\hat{B}_{B_d}} and the renormalization-scale invariant bag constant B^K\hat{B}_K. With the updated CKM matrix we present the currently-allowed range of the ratio ∣Vtd/Vts∣\vert V_{td}/V_{ts} \vert, as well as the standard model predictions for the \bsbsbar\ mixing parameter \xs and the quantities sin⁥2α\sin 2\alpha, sin⁥2ÎČ\sin 2\beta and sin⁥2Îł\sin^2\gamma, which characterize the CP-asymmetries in BB-decays. The ALEPH collaboration has recently reported a significant improvement on the lower limit on the \bs-\bsb mass difference, ΔMs/ΔMd>11.3\Delta M_s/\Delta M_d > 11.3 (95\% C.L.). This has interesting consequences for the CKM parameters which are also worked out. NOTE: this is a revised and updated version of our previous paper.Comment: LaTeX, 27 pages, 16 uuencoded figures (enclosed), CERN-TH.7398/94, UdeM-GPP-TH-94-0

    The exclusive B_s -> phi mu+ mu- process in a constituent quark model

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    We consider the exclusive B_s -> phi mu+ mu- process in the standard model using a constituent quark loop model approach together with a simple parameterization of the quark dynamics. The model allows to compute the decay form factors and therefore can give predictions for the decay rates, the invariant mass spectra and the asymmetries. This process is suppressed in the standard model but can be enhanced if new physics beyond the standard model is present, such as flavor-violating supersymmetric models. It constitutes therefore an interesting precision test of the standard model at forthcoming experiments.Comment: 17 pages, 6 figures, 5 tables, LaTeX; minor changes to the introduction, table III and figure 3. Few references adde

    Two-loop matching of the dipole operators for b→sγb \to s \gamma and b→sgluonb \to s gluon

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    The order αs\alpha_s corrections to the Wilson coefficients of the dipole operators (O7,O8O_7,O_8) at the matching scale ÎŒ=mW\mu =m_W are a crucial ingredient for a complete next- to-leading logarithmic calculation of the branching ratio for b→sÎłb \to s \gamma. Given the phenomenological relevance and the fact that this two-loop calculation has been done so far only by one group [1], we present a detailed re-calculation using a different method. Our results are in complete agreement with those in ref. [1].Comment: 24 pages, latex, 6 figures include

    The 2004 UTfit Collaboration Report on the Status of the Unitarity Triangle in the Standard Model

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    Using the latest determinations of several theoretical and experimental parameters, we update the Unitarity Triangle analysis in the Standard Model. The basic experimental constraints come from the measurements of |V_ub/V_cb|, Delta M_d, the lower limit on Delta M_s, epsilon_k, and the measurement of the phase of the B_d - anti B_d mixing amplitude through the time-dependent CP asymmetry in B^0 to J/psi K^0 decays. In addition, we consider the direct determination of alpha, gamma, 2 beta + gamma and cos(2 beta) from the measurements of new CP-violating quantities, recently performed at the B factories. We also discuss the opportunities offered by improving the precision of the various physical quantities entering in the determination of the Unitarity Triangle parameters. The results and the plots presented in this paper can also be found at http://www.utfit.org, where they are continuously updated with the newest experimental and theoretical results.Comment: 32 pages, 17 figures. High resolution figures and updates can be found at http://www.utfit.org v2: misprints correcte
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