12 research outputs found

    Exclusive semileptonic decays of B mesons into light mesons in the relativistic quark model

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    The exclusive semileptonic Bπ(ρ)eνB\to \pi(\rho) e\nu decays are studied in the framework of the relativistic quark model based on the quasipotential approach in quantum field theory. The large recoil momentum of the final π(ρ)\pi(\rho) meson allows for the expansion of the decay form factors at q2=0q^2=0 in the inverse powers of bb-quark mass. This considerably simplifies the analysis of these decays. The 1/mb1/m_b expansion is carried out up to the first order. It is found that the q2q^2-dependence of the axial form factor A1A_1 is different from the q2q^2-behaviour of other form factors. We find Γ(Bπeν)=(3.1±0.6)×Vub2×1012\Gamma(B\to \pi e\nu)=(3.1\pm 0.6)\times \vert V_{ub}\vert ^2\times 10^{12}s1{}^{-1} and Γ(Bρeν)=(5.7±1.2)×Vub2×1012\Gamma(B\to \rho e\nu)=(5.7\pm 1.2)\times \vert V_{ub}\vert ^2\times 10^{12}s1{}^{-1}. The relation between semileptonic and rare radiative BB-decays is discussed.Comment: 11 pages, Latex, 3 figure

    Solitons in isotropic antiferromagnets: beyond a sigma model

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    Isotropic antiferromagnets shows a reach variety of magnetic solitons with nontrivial static and dynamic properties. One-dimensional soliton elementary excitations have a periodic dispersion law. For two-dimensional case, planar antiferromagnetic vortices having nonsingular macroscopic core with the saturated magnetic moment are present. The dynamic properties of these planar antiferromagnetic vorteces are characterized by presence of a gyroforce

    Properties of heavy quarkonia and B_c mesons in the relativistic quark model

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    The mass spectra and electromagnetic decay rates of charmonium, bottomonium and B_c mesons are comprehensively investigated in the relativistic quark model. The presence of only heavy quarks allows the expansion in powers of their velocities. All relativistic corrections of order v^2/c^2, including retardation effects and one-loop radiative corrections, are systematically taken into account in the computations of the mass spectra. The obtained wave functions are used for the calculation of radiative magnetic dipole (M1) and electric dipole (E1) transitions. It is found that relativistic effects play a substantial role. Their account and the proper choice of the Lorentz structure of the quark-antiquark interaction in a meson is crucial for bringing theoretical predictions in accord with experimental data. A detailed comparison of the calculated decay rates and branching fractions with available experimental data for radiative decays of charmonium and bottomonium is presented. The possibilities to observe the currently missing spin-singlet S and P states as well as D states in bottomonium are discussed. The results for B_c masses and decays are compared with other quark model predictions.Comment: 31 pages, 2 figures, minor correction

    Weak decays of the B_c meson to charmonium and D mesons in the relativistic quark model

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    Semileptonic and nonleptonic decays of the B_c meson to charmonium and D mesons are studied in the framework of the relativistic quark model. The decay form factors are explicitly expressed through the overlap integrals of the meson wave functions in the whole accessible kinematical range. The relativistic meson wave functions are used for the calculation of the decay rates. The obtained results are compared with the predictions of other approaches.Comment: 27 pages, 17 figures, 1 figure and 1 reference added, version to appear in Phys. Rev.
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