952 research outputs found

    Hunting the CKM weak phase with time-integrated Dalitz analyses of Bs -> K pi pi decays

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    We present a new technique to extract information on the Unitarity Triangle from the study of Bs -> K pi pi Dalitz plot. Using isospin symmetry and the possibility to access the decay amplitudes from Dalitz analyses, we propose a new strategy to extract the weak phase gamma from Bs to K pi pi.Comment: 2 pages. v2: Discussion of interference on Dalitz plot clarified. Bs -> K K pi channels removed. v3: Improved discussion of experimental aspects. Final version to appear in Phys. Lett.

    CP violation in supersymmetric theories

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    We review the present status of CP violating problem in supersymmetric extensions of the standard model. We analyze the constraints imposed by the experimental limits of the electron, neutron, and mercury electric dipole moments on the supersymmetric CP phases and show that only the scenarios with flavour-off- diagonal CP violation remain attractive. These scenarios require hermitian Yukawa matrices which naturally arise in models with left-right symmetry or a SU(3) flavour symmetry. In this case, epsilon_K and epsilon'/epsilon can be saturated by a small non-universality of the soft scalar masses through the gluino and chargino contributions respectively. The model also predicts a strong correlation between A_{CP}(b-> s gamma) and the neutron electric dipole moment. In this framework, the standard model gives a the leading contribution to the CP asymmetry in B ->psi K_S decay, while the dominant chargino contribution to this asymmetry is < 0.2. Thus, no constraint is set on the non-universality of this model by the recent BaBar and Belle measureets.Comment: 34 pages, 10 figures. Invited review article for International Journal of Modern Physics

    Status of the CKM matrix

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    An updated determination of the parameters of the Cabibbo-Kobayashi-Maskawa matrix is presented.Comment: 8 pages, 9 figures, uses espcrc2.sty. Talk given at the "7th Topical Seminar on the Legacy of LEP and SLC", 8-11 October 2001, Siena (Italy

    The CKM matrix and CP Violation

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    The status of CP violation and the CKM matrix is reviewed. Direct CP violation in B decay has been established and the measurement of sin(2beta) in \psi K modes reached 5% accuracy. I discuss the implications of these, and of the possible deviations of the CP asymmetries in b->s modes from that in \psi K. The first meaningful measurements of alpha and gamma are explained, together with their significance for constraining both the SM and new physics in B-Bbar mixing. I also discuss implications of recent developments in the theory of nonleptonic decays for B->pi K rates and CP asymmetries, and for the polarization in charmless B decays to two vector mesons.Comment: Plenary talk at 32nd International Conference on High Energy Physics (ICHEP'04), August 16-22, 2004, Beijing, China. v2: Table 5 corrected, minor changes in some averages (updated to hfag, that include correlations between S and C). v3: Figure 8 fixed, minor final change

    B_s to K^(*)0 \bar K^(*)0 decays: the golden channels for new physics searches

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    We point out that time-dependent CP asymmetries in B_s to K^{*0} \bar K^{*0} decays probe the presence of new physics in b to s transitions with an unprecedented theoretical accuracy. We show that, contrary to the case of B_d to phi K_S, it is possible to obtain a model-independent prediction for the coefficient S(B_s to K^{*0} \bar K^{*0}) in the Standard Model. We give an estimate of the experimental precision achievable with the next generation of B physics experiments. We also discuss how this approach can be extended to the case of B_s to \bar K^{*0} K^0, B_s to K^{*0} \bar K^0 and B_s to K^0 \bar K^0 decays and the different experimental challenges for these channels.Comment: 4 pages, 1 figure. v2: Corrected dependence on CKM angles, expanded discussion of multiple polarizations, conclusions strengthened. Final version to appear in PR

    The Chromomagnetic Dipole Operator and the B Semileptonic Branching Ratio

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    We consider the possibility of having a large branching ratio for the decay bsgb\to s g coming from an enhanced Wilson coefficient of the chromomagnetic dipole operator. We show that values of BR(bsg)BR(b\to s g) up to 10%\sim 10\% or more are compatible with the constraints coming from the CLEO experimental results on BR(BXsγ)BR(B\to X_s\gamma) and BR(BXsϕ)BR(B\to X_s\phi). Such large values can reconcile the predictions of both the semileptonic branching ratio and the charm counting with the present experimental results. We also discuss a supersymmetric model with gluino-mediated flavour violations, which can account for such large values of BR(bsg)BR(b\to s g).Comment: 19 pages, 3 eps figures included, replacement with minor change

    Charming Penguins in B decays

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    Full expressions of the Bd0π+πB^0_d \to \pi^+ \pi^- and Bd0π0π0B^0_d \to \pi^0 \pi^0 amplitudes, given in terms of matrix elements of operators of the effective weak Hamiltonian, are used to study the dependence of the relevant branching ratios on the different contributions. The uncertainty in the extraction of the weak phase α\alpha from the measurement of the time-dependent asymmetry in Bd0π+πB^0_d \to \pi^+ \pi^- decays is also analyzed. We find that, among several effects which may enhance the Bd0π0π0B^0_d \to \pi^0 \pi^0 branching ratio, the most important is due to ``charming penguin" diagrams that have never been studied before. These diagrams easily increase BR(Bd0π0π0)BR(B^0_d \to \pi^0 \pi^0) up to a value of 13×1061-3 \times 10^{-6}. The same effect produces, however, a large error in the extraction of α\alpha from the measurement of the Bd0π+πB^0_d \to \pi^+ \pi^- time-dependent asymmetry. We show that it is possible to determine charming-penguin amplitudes from the experimental measurement of many decay rates. Their effect is impressive in B+π+K0B^+ \to \pi^+ K^0 and Bd0K+πB^0_d \to K^+ \pi^- decays, where charming-penguin contributions easily give values of BR(B+π+K0)BR(B^+ \to \pi^+ K^0) and BR(Bd0K+π)BR(B^0_d \to K^+ \pi^-) of about 1×1051 \times 10^{-5}. Among other possibilities, we also suggest to use Bd0K0Kˉ0B^0_d \to K^0 \bar K^0, the BR of which can be as large as 23×1062-3 \times 10^{-6}, to determine the size of charming-penguin amplitudes.Comment: LaTeX, 28 pages, 8 figure
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