54 research outputs found

    CP violation and the CKM angle γ\gamma from angular distributions of untagged BsB_s decays governed by bˉcˉusˉ\bar b\to\bar c u\bar s

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    We demonstrate that time-dependent studies of angular distributions for BsB_s decays caused by bˉcˉusˉ\bar b\to\bar cu\bar s quark-level transitions extract cleanly and model-independently the CKM angle γ\gamma. This CKM angle could be cleanly determined from untagged BsB_s decays alone, if the lifetime difference between the BsB_s mass eigenstates BsLB_s^L and BsHB_s^H is sizable. The time-dependences for the relevant tagged and untagged observables are given both in a general notation and in terms of linear polarization states and should exhibit large CP-violating effects. These observables may furthermore provide insights into the hadronization dynamics of the corresponding exclusive BsB_s decays thereby allowing tests of the factorization hypothesis.Comment: 14 pages, LaTeX, no figure

    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 sin2α\sin 2\alpha, sin2β\sin 2\beta and sin2γ\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

    CP Violation and Lifetime Differences of Neutral B Mesons from Correlated B^0-B^0bar Pairs

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    We present a technique to determine the CP violating phases, as well as, the lifetime differences of the mass eigenstates for both BdB_d and BsB_s, by considering correlated BBˉB\bar{B} pairs produced at the Υ\Upsilon resonances. We do not require a detailed time dependent study, but only partial time integrated rates, with the tag time, either preceding or following the decay of the other BB meson to a final state f. f may be a CP eigenstate or a non-CP eigenstate.Comment: 11 Pages Revte

    CP violation and CKM phases from angular distributions for BsB_s decays into admixtures of CP eigenstates

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    We investigate the time-evolutions of angular distributions for BsB_s decays into final states that are admixtures of CP-even and CP-odd configurations. A sizable lifetime difference between the BsB_s mass eigenstates allows a probe of CP violation in time-dependent untagged angular distributions. Interference effects between different final state configurations of BsDs+DsB_s\to D^{*+}_s D^{*-}_s, J/ψϕJ/\psi \phi determine the Wolfenstein parameter η\eta from untagged data samples, or -- if one uses Vub/Vcb|V_{ub}|/|V_{cb}| as an additional input -- the notoriously difficult to measure CKM angle γ\gamma. Another determination of γ\gamma is possible by using isospin symmetry of strong interactions to relate untagged data samples of BsK+KB_s\to K^{\ast+} K^{\ast-} and BsK0K0B_s\to K^{\ast0} \overline{K^{\ast0}}. We note that the untagged angular distribution for Bsρ0ϕB_s\to\rho^0 \phi provides interesting information about electroweak penguins.Comment: 19 pages, LaTeX, no figure

    CP Violating Lepton Asymmetries from B Decays and Their Implication for Supersymmetric Flavor Models

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    The lepton and dilepton charge asymmetries from BdB_{d} and BsB_{s} are predicted to be small in the standard model, whereas new physics could increase their values significantly. In this paper, we explore the use of the lepton asymmetries as a probe of the flavor structure of supersymmetric theories. In particular, we determine the sensitivity to parameters of various models. We find that in many interesting models which attempt to address the supersymmetric flavor problem, the mixing structure is such that it could be possible to detect new physics. The predictions are model dependent; with a measurement in both the BsB_s and BdB_d systems one can hope to constrain the flavor physics model, especially once squarks are detected and their masses measured. Thus, lepton charge asymmetries can be used as an alternative means of searching for new physics and distinguishing among potential solutions to the flavor problem. They are interesting precisely because they are small in the standard model and are therefore necessarily evidence of new physics.Comment: 22 pages, 2 fig

    The Physics of the B Factories

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    This work is on the Physics of the B Factories. Part A of this book contains a brief description of the SLAC and KEK B Factories as well as their detectors, BaBar and Belle, and data taking related issues. Part B discusses tools and methods used by the experiments in order to obtain results. The results themselves can be found in Part C

    First measurements of hadronic decays of the Z boson

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    We have observed hadronic final states produced in the decays of Z bosons. In order to study the parton structure of these events, we compare the distributions in sphericity, thurst, aplanarity, and number of jets to the predictions of several QCD-based models and to data from lower energies. The data and models agree within the present statistical precision

    Initial measurements of Z-boson resonance parameters in e+e- annihilation

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    We have measured the mass of the Z boson to be 91.11±0.23 GeV/c^2, and its width to be 1.61-0.43+0.60 GeV. If we constrain the visible width to its standard-model value, we find the partial width to invisible decay modes to be 0.62±0.23 GeV, corresponding to 3.8±1.4 neutrino species

    Measurement of the B0^0 and B+^+ meson lifetimes with fully reconstructed hadronic final states

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    The B0 and B+ meson lifetimes have been measured in e+e- annihilation data collected in 1999 and 2000 with the BABAR detector at center-of-mass energies near the Upsilon(4S) resonance. Events are selected in which one B meson is fully reconstructed in a hadronic final state while the second B meson is reconstructed inclusively. A combined fit to the B0 and the B+ decay time difference distributions yields tau_{B0} = 1.546 +/- 0.032 (stat) +/- 0.022(syst) ps, tau_{B+} = 1.673 +/- 0.032 (stat) +/- 0.023 (syst) ps and tau_{B+} / tau_{B0} = 1.082 +/- 0.026 (stat) +/- 0.012 (syst

    The Physics of the B Factories

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