2,482 research outputs found

    Constraints on the parameters of the CKM matrix by End 1998

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    A review of the current status of the Cabibbo-Kobayashi-Maskawa matrix (CKM) is presented. This paper is an update of the results published in [1]. The experimental constraints imposed by the measurements of \epsilon_K, V_{ub}/V_{cb}, \Delta m_d and from the limit on \Delta m_d are used. Values of the constraints and of the parameters entering into the constraints, which restrict the range of the \bar{\rho} and \bar{\eta} parameters, include recent measurements presented at 1998 Summer Conferences and progress obtained by lattice QCD collaborations. The results are: \bar{\rho}=0.202 ^{+0.053}_{-0.059},\bar{\eta}=0.340 \pm 0.035, from which the angles \alpha, \beta and \gamma of the unitarity triangle are inferred : \sin 2 \alpha = -0.26 ^{+ 0.29}_{-0.28} ,\sin 2 \beta = 0.725 ^{+0.050}_{-0.060} ,\gamma= (59.5^{+8.5}_{-7.5})^{\circ}. Without using the constraint from \epsilon_K, \sin 2 \beta has been obtained: \sin 2 \beta = 0.72 ^{+0.07}_{-0.11}. Several external measurements or theoretical inputs have been removed, in turn, from the constraints and their respective probability density functions have been obtained. Central values and uncertainties on these quantities have been compared with actual measurements or theoretical evaluations. In this way it is possible to quantify the importance of the different measurements and the coherence of the Standard Model scenario for CP violation. An important result is that \Delta m_s is expected to be between [12.0-17.6] ps^{-1} with 68% C.L. and <20 ps^{-1} at 95% C.L. Finally relations between the CKM parameters and the quark masses are examined within a given model.Comment: 26 page

    Heavy Quark Parameters and Vcb from Spectral Moments in Semileptonic B Decays

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    We extract the heavy quark masses and non-perturbative parameters from the Delphi preliminary measurements of the first three moments of the charged lepton energy and hadronic mass distributions in semileptonic B decays, using a multi-parameter fit. We adopt two formalisms, one of which does not rely on a 1/mc expansion and makes use of running quark masses. The data are consistent and the level of accuracy of the experimental inputs largely determines the present sensitivity. The results allow to improve on the uncertainty in the extraction of Vcb.Comment: 13 pages, 2 figure

    Constraints on the parameters of the VCKMV_{CKM} matrix at the end of 1997

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    A review of the current status of the Cabibbo-Kobayashi-Maskawa matrix V_CKM is presented. This paper contains an update of the results published in hep-ph/9711261. Values of the parameters entering into the constraints, which restrict the range for rho and eta parameters, include recent measurements given at 1997 Summer Conferences and progress obtained by lattice QCD collaborations.Experimental constraints imposed by the measurements of epsilon_k,V_ub/V_cb, Delta m_d and by the limit on Delta m_s, are compatible and do not show evidence for New Physics inside measurements errors. Values for the angles alpha, beta and gamma of the C.K.M. triangle have been also obtained: rho=0.156 +- 0.090, eta=0.328 +- 0.054 sin 2alpha = -0.10+-0.40, sin 2beta = 0.68 +- 0.10, gamma= 64+-12 Angles theta,theta_u,theta_d and phi proposed in the parametrisation (Phys. Lett. B5353 (1995) 114.) of the C.K.M. matrix have been also determined. Finally, as there are more constraints than the fitted rho and eta parameters, several external measurements or theoretical inputs have been removed, in turn, from the constraints and their respective values have been fitted simultaneously with rho and eta.Central values and uncertainties on these quantities have been compared with actual measurements or theoretical evaluations. In this way it is possible to quantify the importance of the different measurements and the coherence of the Standard Model scenario for CP violation.Comment: 29 page

    Proposal to study BsDˉsJB_s \to \bar D_{sJ} transitions

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    It is proposed to clear some of the puzzles of B decay to the broad Dˉ\bar{D}^{\ast\ast} states by studying the corresponding decay with strange states Bs0Ds0π+B_s^0 \to D_{s0}^{\ast -} \pi^+ at LHCb. Interpretation of the results should be easier due to the narrowness of the Ds0D_{s0}^{\ast -} state.Comment: 21 page

    2000 CKM-Triangle Analysis A Critical Review with Updated Experimental Inputs and Theoretical Parameters

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    Within the Standard Model, a review of the current determination of the sides and angles of the CKM unitarity triangle is presented, using experimental constraints from the measurements of |\epsilon_K|, |V_{ub}/V_{cb}|, \Delta m_d and from the limit on \Delta m_s, available in September 2000. Results from the experimental search for {B}^0_s-\bar{B}^0_s oscillations are introduced in the present analysis using the likelihood. Special attention is devoted to the determination of the theoretical uncertainties. The purpose of the analysis is to infer regions where the parameters of interest lie with given probabilities. The BaBar "95 %, C.L. scanning" method is also commented.Comment: 44 pages (revised version

    Determination of the CKM unitarity triangle parameters by end 1999

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    Within the Standard Model, a review of the current determination of the CKM unitarity triangle parameters is presented, using experimental constraints from the measurements of |epsilon_K|, V_ub/V_cb, Delta m_d and from the limit on Delta m_s, available by end 1999.Comment: Talk given by A. Stocchi at the Third International Conference on B physics and CP violation, National Taiwan Univ., Taipei, Tawain, December 3-7, 199

    Constraints on new physics from the quark mixing unitarity triangle

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    The status of the Unitarity Triangle beyond the Standard Model including the most recent results on Delta m_s, on dilepton asymmetries and on width differences is presented. Even allowing for general New Physics loop contributions the Unitarity Triangle must be very close to the Standard Model result. With the new measurements from the Tevatron, we obtain for the first time a significant constraint on New Physics in the B_s sector. We present the allowed ranges of New Physics contributions to Delta F=2 processes, and of the time-dependent CP asymmetry in B_s to J/Psi phi decays.Comment: 5 pages, 4 figures. v2: numerical error in Delta Gamma_s/Gamma_s corrected. Plots and tables updated. v3: update after ICHEP06, final version published in Phys Rev Letter
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