Constraints on the parameters of the CKM matrix by End 1998

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

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

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 Bs→DˉsJB_s \to \bar D_{sJ} transitions

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

Determination of the CKM unitarity triangle parameters by end 1999

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

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

Extraction of the x-dependence of the non-perturbative QCD b-quark fragmentation distribution component

Using recent measurements of the b-quark fragmentation distribution obtained in $e^+e^- \to b \bar{b}$ events registered at the Z pole, the non-perturbative QCD component of the distribution has been extracted independently of any hadronic physics modelling. This distribution depends only on the way the perturbative QCD component has been defined. When the perturbative QCD component is taken from a parton shower Monte-Carlo, the non-perturbative QCD component is rather similar with those obtained from the Lund or Bowler models. When the perturbative QCD component is the result of an analytic NLL computation, the non-perturbative QCD component has to be extended in a non-physical region and thus cannot be described by any hadronic modelling. In the two examples used to characterize these two situations, which are studied at present, it happens that the extracted non-perturbative QCD distribution has the same shape, being simply translated to higher-x values in the second approach, illustrating the ability of the analytic perturbative QCD approach to account for softer gluon radiation than with a parton shower generator.Comment: 13 page

Parametrisations of the D -> K l nu form factor and the determination of \hat{g}

The vector form factor f_+(t) of the semileptonic decay D -> K l nu, measured recently with a high accuracy, can be used to determine the strong coupling constant g_{D_s^* D K}. The latter is related to the normalised coupling \hat{g} releveant in heavy-meson chiral perturbation theory. This determination relies on the estimation of the residue of the form factor at the D_s^* pole and thus on an extrapolation of the form factor in the unphysical region (m_D-m_K)^2<t<(m_D+m_K)^2. We test this extrapolation for several parametrisations of the form factors by determining the value of \hat{g}, whose value can be compared to other (experimental and theoretical) estimates. Several unsophisticated parametrisations, differing by the amount of physical information that they embed, are shown to pass this test. An apparently more elaborated parametrisation of form factors, the so-called z-expansion, is at variance with the other models, and we point out some significant shortcomings of this parametrisation for the problem under consideration.Comment: 16 pages, 2 figures. A few references added. Accepted for publication in JoP