1,833 research outputs found

    Final state phases in B -> D\pi, \bar{D}\pi decays and CP-asymmetry

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    Final state phases \delta_f and \delta_f' in B-> D pi, barD pi decays are shown to be equal i.e. \delta =\delta_f-\delta_f' = 0. Thus CP-violating asymmetry A(t) is independent of final state phases. The estimate for the phases \delta_f and \delta_f' is also given.Comment: 6 pages, no figur

    Determination of the CP Violating Phase γ\gamma by a Sum Over Common Decay Modes to BsB_s and Bˉs\bar{B}_s

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    To help the difficult determination of the angle γ\gamma of the unitarity triangle, Aleksan, Dunietz and Kayser have proposed the modes of the type KDs+K^-D^+_s, common to BsB_s and Bˉs\bar{B}_s. We point out that it is possible to gain in statistics by a sum over all modes with ground state mesons in the final state, i.e. KDs+K^-D^+_s, KD+sK^{*-}D_+^s, KDs+K^-D^{*+}_s, KDs+K^{*-}D^{*+}_s. The delicate point is the relative phase of these different contributions to the dilution factor DD of the time-dependent asymmetry. Each contribution to DD is proportional to a product FcbF^{cb} FubF^{ub} fDsf_{D_s} fKf_K where FF denotes form factors and ff decay constants. Within a definite phase convention, lattice calculations do not show any change in sign when extrapolating to light quarks the form factors and decay constants. Then, we can show that all modes contribute constructively to the dilution factor, except the PP-wave KDs+K^{*-}D^{*+}_s, which is small. Quark model arguments based on wave function overlaps also confirm this stability in sign. By summing over all these modes we find a gain of a factor 6 in statistics relatively to KDs+K^-D^+_s. The dilution factor for the sum DtotD_{tot} is remarkably stable for theoretical schemes that are not in very strong conflict with data on BψK(K)B \to \psi K(K^*) or extrapolated from semileptonic charm form factors, giving Dtot0.6D_{tot} \geq 0.6, always close to D(KDs+)D(K^- D^+_s).Comment: 22 pages, LPTHE Orsay 94/03, DAPNIA/SPP/94-2

    Phenomenological discussion of BPVB\to P V decays in QCD improved factorization approach

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    Trying a global fit of the experimental branching ratios and CP-asymmetries of the charmless BPVB\to PV decays according to QCD factorization, we find it impossible to reach a satisfactory agreement, the confidence level (CL) of the best fit is smaller than .1 %. This failure reflects the difficulty to accommodate several large experimental branching ratios of the strange channels. Furthermore, experiment was not able to exclude a large direct CP asymmetry in Bˉ0ρ+π\bar {B}^0\to\rho^+ \pi^-, which is predicted very small by QCD factorization. Proposing a fit with QCD factorization complemented by a charming-penguin inspired model we reach a best fit which is not excluded by experiment (CL of about 8 %) but is not fully convincing. These negative results must be tempered by the remark that some of the experimental data used are recent and might still evolve significantly.Comment: 8 pages, 2 figures (requires epsfig, psfrag),talk presented at the XXXVIIIth Rencontres de Moriond: Electroweak Interactions and Unified Theories,Les Arcs, France, March 15-22, 2003. To be published in the Proceeding

    TLEP, first step in a long-term vision for HEP

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    The discovery of H(126) has renewed interest in circular e+e- colliders that can operate as Higgs factories, which benefit from three unique characteristics: i) high luminosity and reliability, ii) the availability of several interaction points, iii) superior beam energy accuracy. TLEP is an e+e- storage ring of 80-km circumference that can operate with very high luminosity from the Z peak (90 GeV) to the top quark pair threshold (350 GeV). It can achieve transverse beam polarization at the Z peak and WW threshold, giving it unparalleled accuracy on the beam energy. A preliminary study indicates that an 80 km tunnel could be constructed around CERN. Such a tunnel would allow a 100 TeV proton-proton collider to be established in the same ring (VHE-LHC), offering a long term vision.Comment: This is a contribution to the the Snowmass process 2013: Frontier Capabilitie

    Hunting for the alpha: BρρB\to \rho\rho, BππB \to \pi\pi, BπρB \to\pi\rho

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    The hypothesis of the smallness of penguin contribution to charmless strangeless Bd(Bˉd)B_d (\bar B_d) decays allows to determine with high accuracy the value of angle α\alpha from the currently available BρρB \to \rho\rho, BππB \to \pi\pi and BρπB\to \rho\pi decay data.Comment: 9 page

    Comments on "Wall-plug (AC) power consumption of a very high energy e+/e- storage ring collider" by Marc Ross

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    The paper arXiv:1308.0735 questions some of the technical assumptions made by the TLEP Steering Group when estimating in arXiv:1305.6498 the power requirement for the very high energy e+e- storage ring collider TLEP. We show that our assumptions are based solidly on CERN experience with LEP and the LHC, as well accelerators elsewhere, and confirm our earlier baseline estimate of the TLEP power consumption.Comment: 6 page

    Extracting Weak Phase Information from B -> V_1 V_2 Decays

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    We describe a new method for extracting weak, CP-violating phase information, with no hadronic uncertainties, from an angular analysis of B -> V_1 V_2 decays, where V_1 and V_2 are vector mesons. The quantity sin2(2β+γ)\sin^2 (2\beta + \gamma) can be cleanly obtained from the study of decays such as B_d^0(t) -> D^{*\pm} \rho^\mp, D^{*\pm} a_1^{\mp}, D^{*0} K^{*0}, etc. Similarly, one can use B_s^0(t) -> D_s^{*\pm} K^{*\mp} to extract sin2γ\sin^2 \gamma. There are no penguin contributions to these decays. It is possible that sin2(2β+γ)\sin^2 (2\beta + \gamma) will be the second function of CP phases, after sin2β\sin 2\beta, to be measured at B-factories.Comment: 4 pages, RevTeX, no figure
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