4,447 research outputs found

    Nonleptonic Weak Decays of B to D_s and D mesons

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    Branching ratios and polarization amplitudes for B decaying to all allowed pseudoscalar, vector, axial-vector, scalar and tensor combinations of D_s and D mesons are calculated in the Isgur Scora Grinstein Wise (ISGW) quark model after assuming factorization. We find good agreement with other models in the literature and the limited experimental data and make predictions for as yet unseen decay modes. Lattice QCD results in this area are very limited. We make phenomenological observations on decays in to D_s(2317) and D_s(2460) and propose tests for determining the status and mixings of the axial mesons. We use the same approach to calculate branching ratios and polarization fraction for decays in to two D type mesons.Comment: 21 pages, 9 figures. v3: updated to reflect changes in published paper, conclusions unchanged (see source file for details). Added comments on factorization. v2: experimental data updated, references added, tables of results added, more on axial D_s mixing, added section on D D decay modes and typos correcte

    Simply Modeling Meson HQET

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    A simple relativistic model of heavy-quark-light-quark mesons is proposed. In an expansion in inverse powers of the heavy quark mass we find that all zeroth and first order heavy quark symmetry relations are satisfied. The main results are: - the difference between the meson mass and the heavy quark mass plays a significant role even at zeroth order; - the slope of the Isgur-Wise function at the zero recoil point is typically less than −1-1; - the first order correction to the pseudoscalar decay constant is large and negative; - the four universal functions describing the first order corrections to the semileptonic decay form factors are small; - these latter corrections are quite insensitive to the choice of model parameters, and in particular to the effects of hyperfine mass splitting.Comment: 17 pages, LaTeX, 3 LaTeX figures in separate file, UTPT-92-16. This is the version published long ago but not previously archive

    Second Order Power Corrections in the Heavy Quark Effective Theory I. Formalism and Meson Form Factors

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    In the heavy quark effective theory, hadronic matrix elements of currents between two hadrons containing a heavy quark are expanded in inverse powers of the heavy quark masses, with coefficients that are functions of the kinematic variable v⋅v′v\cdot v'. For the ground state pseudoscalar and vector mesons, this expansion is constructed at order 1/mQ21/m_Q^2. A minimal set of universal form factors is defined in terms of matrix elements of higher dimension operators in the effective theory. The zero recoil normalization conditions following from vector current conservation are derived. Several phenomenological applications of the general results are discussed in detail. It is argued that at zero recoil the semileptonic decay rates for B→D ℓ νB\to D\,\ell\,\nu and B→D∗ℓ νB\to D^*\ell\,\nu receive only small second order corrections, which are unlikely to exceed the level of a few percent. This supports the usefulness of the heavy quark expansion for a reliable determination of VcbV_{cb}.Comment: (34 pages, REVTEX, two postscript figures available upon request), SLAC-PUB-589

    Two-loop corrections to the Isgur-Wise function in QCD sum rules

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    We complete the QCD sum rule analysis of the Isgur Wise form factor ξ(v⋅v′)\xi(v\cdot v') at next-to-leading order in renormalization-group improved perturbation theory. To this end, the exact result for the two-loop corrections to the perturbative contribution is derived using the heavy quark effective theory. Several techniques for the evaluation of two-loop integrals involving two different types of heavy quark propagators are discussed in detail, among them the methods of integration by parts and differential equations. The order-αs\alpha_s corrections to the Isgur-Wise function turn out to be small and well under control. At large recoil, they tend to decrease the form factor by 5−10%5-10\%.Comment: 24 pages (REVTEX), 2 figures available upon request, SLAC-PUB-599

    QCD Sum Rules Calculation of Heavy Λ\Lambda Semileptonic Decay

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    We set up sum rules for heavy lambda decays in a full QCD calculation which in the heavy quark mass limit incorporates the symmetries of heavy quark effective theory. For the semileptonic \La_c decay we obtain a reasonable agreement with experiment. For the \La_b semileptonic decay we find at the zero recoil point a violation of the heavy quark symmetry of about 20%.Comment: Revised version. Title changed. 11 pages (RevTex), 4 PS figure

    Particle simulations of relativistic electron beam injection from spacecraft

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94852/1/jgra16416.pd

    Low temperature phase diagram and critical behaviour of the four-state chiral clock model

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    The low temperature behaviour of the four-state chiral clock (CC4CC_4) model is reexamined using a systematic low temperature series expansion of the free energy. Previously obtained results for the low temperature phases are corrected and the low temperature phase diagram is derived. In addition, the phase transition from the modulated region to the high temperature paraphase is shown to belong to the universality class of the 3d-XY model.Comment: 17 pages in ioplppt style, 3 figure

    The Subleading Isgur-Wise Form Factor χ3(v⋅v′)\chi_3(v\cdot v') to Order αs\alpha_s in QCD Sum Rules

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    We calculate the contributions arising at order αs\alpha_s in the QCD sum rule for the spin-symmetry violating universal function χ3(v⋅v′)\chi_3(v\cdot v'), which appears at order 1/mQ1/m_Q in the heavy quark expansion of meson form factors. In particular, we derive the two-loop perturbative contribution to the sum rule. Over the kinematic range accessible in B→D(∗)ℓ νB\to D^{(*)}\ell\,\nu decays, we find that χ3(v⋅v′)\chi_3(v\cdot v') does not exceed the level of ∼1%\sim 1\%, indicating that power corrections induced by the chromo-magnetic operator in the heavy quark expansion are small.Comment: 12 pages ReVTeX, 3 figures available upon request, SLAC-PUB-6017, WIS-92/99/Dec-P

    An Analytic Formula and an Upper Bound for epsilon'/epsilon in the Standard Model

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    Using the idea of the penguin box expansion we find an analytic expression for epsilon'/epsilon in the Standard Model as a function of m_t, m_s(m_c) and two non-perturbative parameters B_6 and B_8. This formula includes next-to-leading QCD/QED short distance effects calculated recently by means of the operator product expansion and renormalization group techniques. We also derive an analytic expression for the upper bound on epsilon'/epsilon as a function of |V_cb|, |V_ub/V_cb|, B_K and other relevant parameters. Numerical examples of the bound are given.Comment: 10 pages with 1 figure appended in PostScript format; MPI preprint MPI-Ph/93-60 and TU preprint TUM-T31-47/9
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