197 research outputs found

    Baryons with Two Heavy Quarks as Solitons

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    Using the chiral soliton model and heavy quark symmetry we study baryons containing two heavy quarks. If there exists a stable (under strong interactions) meson consisting of two heavy quarks and two light ones, then we find that there always exists a state of this meson bound to a chiral soliton and to a chiral anti-soliton, corresponding to a two heavy quark baryon and a baryon containing two heavy anti-quarks and five light quarks, or a ``heptaquark".Comment: 7 pages and 2 postscript figures appended, LaTex, UCI-TR 94-3

    Direct CP Violation in Hadronic B Decays

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    There are different approaches for the hadronic B decay calculations, recently. In this paper, we upgrade three of them, namely factorization, QCD factorization and the perturbative QCD approach based on kTk_T factorization, by using new parameters and full wave functions. Although they get similar results for many of the branching ratios, the direct CP asymmetries predicted by them are different, which can be tested by recent experimental measurements of B factories.Comment: 11 pages, 3 figures, revtex4, Talk given at the Workshop on the Frontiers of Theoretical Physics and Cross-Disciplinary, NSFC, Beijing, March 200

    Localized Fermions and Anomaly Inflow via Deconstruction

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    We study fermion localization in gauge theory space. We consider four dimensional product gauge groups in which light chiral fermions transform under different gauge factors of the product group. This construction provides a suppression of higher dimensional operators. For example, it can be used to suppress dangerous proton decay operators. The anomalies associated with the light chiral fermions are compensated by Wess-Zumino terms, which in the continuum limit reproduce the five dimensional Chern-Simons term.Comment: 12 pages, minor changes to section

    Lorentz and Galilei Invariance on Lattices

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    We show that the algebraic aspects of Lie symmetries and generalized symmetries in nonrelativistic and relativistic quantum mechanics can be preserved in linear lattice theories. The mathematical tool for symmetry preserving discretizations on regular lattices is the umbral calculus.Comment: 5 page

    B ->PV Decays in the QCD Improved Factorization Approach

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    Motivated by recent CELO measurements and the progress of the theory of B decays, we investigate B→PV(P=π,K.V=K∗,ρ,ω)B\to P V(P=\pi,K. V= K^{*},\rho,\omega) decay modes in the framework of QCD improved factorization. We find that all the measured branching ratios are well accommodated in the reasonable parameter space and predictions for the other decay modes are well below the experimental upper limits. We also have calculated CP asymmetries in these decay modes.Comment: 24 pages, LaTex-2e, typos correcte

    Branching Ratio and CP Violation of B to pi pi Decays in Perturbative QCD Approach

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    We calculate the branching ratios and CP asymmetries for B^0 to pi^+pi^-, B^+ to pi^+pi^0 and B^0 to pi^0pi^0 decays, in a perturbative QCD approach. In this approach, we calculate non-factorizable and annihilation type contributions, in addition to the usual factorizable contributions. We found that the annihilation diagram contributions are not very small as previous argument. Our result is in agreement with the measured branching ratio of B to pi^+pi^- by CLEO collaboration. With a non-negligible contribution from annihilation diagrams and a large strong phase, we predict a large direct CP asymmetry in B^0 to pi^+pi^-, and pi^0pi^0, which can be tested by the current running B factories.Comment: Latex, 28 pages including 11 figures; added contents and figures, corrected typo

    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 B→πρB \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 B0→π0ρ0B^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

    Measuring ∣Vub∣|V_{ub}| with B→Ds+Xu\to D_s^+ X_u transitions

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    We propose the determination of the CKM matrix element ∣Vub∣|V_{ub}| by the measurement of the spectrum of B→Ds+XuB \to D_s^+ X_u, dominated by the spectator quark model mechanism bˉ→Ds(∗)+uˉ\bar{b} \to D_s^{(*)+} \bar{u}. The interest of considering B→Ds+XuB \to D_s^+X_u versus the semileptonic decay is that more than 50 % of the spectrum for B→Ds+XuB \to D_s^+ X_u occurs above the kinematical limit for B→Ds+XcB \to D_s^+ X_c, while most of the spectrum B→lÎœXuB \to l \nu X_u occurs below the B→lÎœXcB \to l \nu X_c one. Furthermore, the measure of the hadronic mass MXM_X is easier in the presence of an identified DsD_s than when a Îœ\nu has been produced. As a consistency check, we point out that the rate bˉ→Ds(∗)+cˉ\bar{b} \to D_s^{(*)+} \bar{c} (including QCD corrections that we present elsewhere) is consistent with the measured BR(B→Ds±X)BR (B \to D_s^{\pm} X). Although the hadronic complications may be more severe in the mode that we propose than in the semileptonic inclusive decay, the end of the spectrum in B→lÎœXuB \to l \nu X_u is not well understood on theoretical grounds. We argue that, in our case, the excited Ds∗∗D_s^{**}, decaying into DKD K, do not contribute and, if there is tagging of the BB meson, the other mechanisms to produce a DsD_s of the right sign are presumably small, of O(10−2)O(10^{-2}) relative to the spectator amplitude, or can be controlled by kinematical cuts. In the absence of tagging, other hadronic backgrounds deserve careful study. We present a feasability study with the BaBar detector.Comment: 22 pages, LaTe

    Lifetimes of Heavy-Flavour Hadrons -- Whence and Whither?

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    A theoretical treatment for the weak decays of heavy-flavour hadrons has been developed that is genuinely based on QCD. Its methodology as it applies to total lifetimes and the underlying theoretical issues are sketched. Predictions are compared with present data. One discrepancy emerges: the beauty baryon lifetime appears to be significantly shorter than expected. The ramifications of those findings are analyzed in detail.Comment: 15 pages, no figures, LATEX, two references added and new information concerning a lower charm content in B decays incorporate

    Perturbative approach to the penguin-induced B→πϕB \to \pi \phi

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    Using a modified perturbative approach that includes the Sudakov resummation and transverse degrees of freedom we analyze the penguin-induced B−→π−ϕB^{-} \to \pi^{-}\phi decay by applying the next-to-leading order effective weak Hamiltonian. The modified perturbative method enables us to include nonfactorizable contributions and to control virtual momenta appearing in the process. Besides, we apply the three-scale factorization theorem for nonleptonic processes that offers the possibility of having the scale-independent product of short- and long-distance parts in the amplitude of the weak Hamiltonian. The calculation supports the results obtained in the BSW factorization approach, illustrating the electroweak penguin dominance and the branching ratio of order O(10−8){\cal O}(10^{-8}). However, the estimated prediction of 16% for the CP asymmetry is much larger than that obtained in the factorization approach.Comment: RevTex, 25 pages, 4 PostScript figures included, revised version, to be published in Phys.Rev.
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