665 research outputs found

    Updates of WRW_R effects on CP angles determination in B decays

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    The recently observed CP violation in B decay and BB-\ovar{B} mixing data put constraints on the mass of WRW_R and the parameters of the right-handed current quark mixing matrix VRV^R in SU(2)L×SU(2)R×U(1)SU(2)_L \times SU(2)_R\times U(1) gauge model. It is shown that the allowed region of parameters are severely restricted for light WRW_R with mass on the order of 1 TeV. There exist sets of parameters which can accommodate large CP violation as measured by Belle, sin2ϕ1exp1\sin2\phi_1|_{exp}\simeq 1, for MWR=110M_{W_R}=1 \sim 10 TeV.Comment: 11pages, 19 figures, LaTeX2

    Study of color suppressed modes B0Dˉ()0η()B^0 \to \bar D^{(*)0} \eta^{(\prime)}

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    The color suppressed modes B0Dˉ()0η()B^0 \to \bar D^{(*)0} \eta^{(\prime)} are analyzed in perturbative QCD approach. We find that the dominant contribution is from the non-factorizable diagrams. The branching ratios calculated in our approach for B0Dˉ()0ηB^0 \to \bar D^{(*)0} \eta agree with current experiments. By neglecting the gluonic contribution, we predict the branching ratios of B0Dˉ()0ηB^0 \to \bar D^{(*)0} \eta' are at the comparable size of B0Dˉ()0π0B^0 \to \bar D^{(*)0} \pi^0, but smaller than that of B0Dˉ()0ηB^0 \to \bar D^{(*)0} \eta .Comment: revtex, 5 pages, axodraw.st

    Study of BDπB\to D^{**} \pi decays

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    We investigate the production of the novel PP-wave mesons D0D^{*}_{0} and D1(D1)D^{\prime}_{1} (D_{1}), identified as JP=0+J^{P}=0^+ and 1+1^+, in heavy BB meson decays, respectively. With the heavy quark limit, we give our modelling wave functions for the scalar meson D0D^{*}_{0}. Based on the assumptions of color transparency and factorization theorem, we estimate the branching ratios of BD0πB\to D^{*}_{0} \pi decays in terms of the obtained wave functions. Some remarks on D1()D^{(\prime)}_{1} productions are also presented.Comment: 16 pages, 2 figures, Revtex4, to be published in Phys. Rev.

    Nonfactorizable contributions to BD()MB \to D^{(*)} M decays

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    While the factorization assumption works well for many two-body nonleptonic BB meson decay modes, the recent measurement of BˉD()0M0\bar B\to D^{(*)0}M^0 with M=πM=\pi, ρ\rho and ω\omega shows large deviation from this assumption. We analyze the BD()MB\to D^{(*)}M decays in the perturbative QCD approach based on kTk_T factorization theorem, in which both factorizable and nonfactorizable contributions can be calculated in the same framework. Our predictions for the Bauer-Stech-Wirbel parameters, a2/a1=0.43±0.04|a_2/a_1|= 0.43\pm 0.04 and Arg(a2/a1)42Arg(a_2/a_1)\sim -42^\circ and a2/a1=0.47±0.05|a_2/a_1|= 0.47\pm 0.05 and Arg(a2/a1)41Arg(a_2/a_1)\sim -41^\circ, are consistent with the observed BDπB\to D\pi and BDπB\to D^*\pi branching ratios, respectively. It is found that the large magnitude a2|a_2| and the large relative phase between a2a_2 and a1a_1 come from color-suppressed nonfactorizable amplitudes. Our predictions for the Bˉ0D()0ρ0{\bar B}^0\to D^{(*)0}\rho^0, D()0ωD^{(*)0}\omega branching ratios can be confronted with future experimental data.Comment: 25 pages with Latex, axodraw.sty, 6 figures and 5 tables, Version published in PRD, Added new section 5 and reference

    kTk_T factorization of exclusive processes

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    We prove kTk_T factorization theorem in perturbative QCD (PQCD) for exclusive processes by considering πγγ(π)\pi\gamma^*\to \gamma(\pi) and Bγ(π)lνˉB\to\gamma(\pi) l\bar\nu. The relevant form factors are expressed as the convolution of hard amplitudes with two-parton meson wave functions in the impact parameter bb space, bb being conjugate to the parton transverse momenta kTk_T. The point is that on-shell valence partons carry longitudinal momenta initially, and acquire kTk_T through collinear gluon exchanges. The bb-dependent two-parton wave functions with an appropriate path for the Wilson links are gauge-invariant. The hard amplitudes, defined as the difference between the parton-level diagrams of on-shell external particles and their collinear approximation, are also gauge-invariant. We compare the predictions for two-body nonleptonic BB meson decays derived from kTk_T factorization (the PQCD approach) and from collinear factorization (the QCD factorization approach).Comment: 11 pages, REVTEX, 5 figure

    Semileptonic B(Bs,Bc)B(B_s, B_c) decays in the light-cone QCD sum rules

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    Semileptonic BB(Bs,BcB_s, B_c) decays are investigated systematically in the light-cone QCD sum rules. Special emphasis is put on the LCSR calculation on weak form factors with an adequate chiral current correlator, which turns out to be particularly effective to control the pollution by higher twist components of spectator mesons. The result for each channel depends on the distribution amplitude of the the producing meson. The leading twist distribution amplitudes of the related heavy mesons and charmonium are worked out by a model approach in the reasonable way. A practical scenario is suggested to understand the behavior of weak form factors in the whole kinematically accessible ranges. The decay widths and branching ratios are estimated for several BB(BcB_c) decay modes of current interest.Comment: 8 pages, talk given by the first arthur at 4th International Conference on Flavor Physics (ICFP 2007), Beijing, China, Sept 24-28, 200

    Threshold resummation for exclusive B meson decays

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    We argue that double logarithmic corrections αsln2x\alpha_s\ln^2 x need to be resumed in perturbative QCD factorization theorem for exclusive BB meson decays, when the end-point region with a momentum fraction x0x\to 0 is important. These double logarithms, being of the collinear origin, are absorbed into a quark jet function, which is defined by a matrix element of a quark field attached by a Wilson line. The factorization of the jet function from the decay BγlνˉB\to\gamma l\bar\nu is proved to all orders. Threshold resummation for the jet function leads to a universal, {\it i.e.}, process-independent, Sudakov factor, whose qualitative behavior is analyzed and found to smear the end-point singularities in heavy-to-light transition form factors.Comment: 10 pages, more details are include

    Revisiting the B {\to} {\pi} {\rho}, {\pi} {\omega} Decays in the Perturbative QCD Approach Beyond the Leading Order

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    We calculate the branching ratios and CP asymmetries of the BπρB \to \pi \rho, πω\pi\omega decays in the perturbative QCD factorization approach up to the next-to-leading-order contributions. We find that the next-to-leading-order contributions can interfere with the leading-order part constructively or destructively for different decay modes. Our numerical results have a much better agreement with current available data than previous leading-order calculations, e.g., the next-to-leading-order corrections enhance the B0π0ρ0B^0\rightarrow \pi^0\rho^0 branching ratios by a factor 2.5, which is helpful to narrow the gaps between theoretic predictions and experimental data. We also update the direct CP-violation parameters, the mixing-induced CP-violation parameters of these modes, which show a better agreement with experimental data than many of the other approaches.Comment: 23 pages, 4 figures, 4 table

    Perturbative QCD analysis of BϕKB \to \phi K^* decays

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    We study the first observed charmless BVVB\to VV modes, the BϕKB\to\phi K^* decays, in perturbative QCD formalism. The obtained branching ratios B(BϕK)15×106B(B\to\phi K^*)\sim 15 \times 10^{-6} are larger than 9×106\sim 9\times 10^{-6} from QCD factorization. The comparison of the predicted magnitudes and phases of the different helicity amplitudes, and branching ratios with experimental data can test the power counting rules, the evaluation of annihilation contributions, and the mechanism of dynamical penguin enhancement in perturbative QCD, respectively.Comment: 14 pages, 2 tables, brief disscussion on hard sacle added, version to appear in PR

    Branching ratios of B+D()+K()0B^+ \to D^{(*)+}K^{(*)0} decays in perturbative QCD approach

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    We study the rare decays B+D()+K()0B^+ \to D^{(*)+}K^{(*)0}, which can occur only via annihilation type diagrams in the standard model. We calculate all of the four modes, BPP,VP,PV,VVB \to PP, VP, PV, VV, in the framework of perturbative QCD approach and give the branching ratios of the order about 10610^{-6}.Comment: 18 pages, 1 figure, Revte
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