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

The exclusive semileptonic $B\to \pi(\rho) e\nu$ 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 $\pi(\rho)$ meson allows for the expansion of the decay form factors at $q^2=0$ in the inverse powers of $b$-quark mass. This considerably simplifies the analysis of these decays. The $1/m_b$ expansion is carried out up to the first order. It is found that the $q^2$-dependence of the axial form factor $A_1$ is different from the $q^2$-behaviour of other form factors. We find $\Gamma(B\to \pi e\nu)=(3.1\pm 0.6)\times \vert V_{ub}\vert ^2\times 10^{12}$s${}^{-1}$ and $\Gamma(B\to \rho e\nu)=(5.7\pm 1.2)\times \vert V_{ub}\vert ^2\times 10^{12}$s${}^{-1}$. The relation between semileptonic and rare radiative $B$-decays is discussed.Comment: 11 pages, Latex, 3 figure

Hyperfine structure of the ground state muonic He-3 atom

On the basis of the perturbation theory in the fine structure constant $\alpha$ and the ratio of the electron to muon masses we calculate one-loop vacuum polarization and electron vertex corrections and the nuclear structure corrections to the hyperfine splitting of the ground state of muonic helium atom $(\mu\ e \ ^3_2He)$. We obtain total result for the ground state hyperfine splitting $\Delta \nu^{hfs}=4166.471$ MHz which improves the previous calculation of Lakdawala and Mohr due to the account of new corrections of orders $\alpha^5$ and $\alpha^6$. The remaining difference between our theoretical result and experimental value of the hyperfine splitting lies in the range of theoretical and experimental errors and requires the subsequent investigation of higher order corrections.Comment: Talk on poster section of XXIV spectroscopy congress, 28 February-5 March 2010, Moscow-Troitsk, Russia, 21 pages, LaTeX, 8 figure

Heavy quark 1/mQ1/m_{Q} contributions in semileptonic B decays to orbitally excited D mesons

Exclusive semileptonic decays of B mesons to orbitally excited D mesons are considered beyond the infinitely heavy quark limit in the framework of the relativistic quark model based on the quasipotential approach. This model agrees with the structure of heavy quark mass corrections predicted by the heavy quark effective theory and allows the determination of corresponding leading and subleading Isgur-Wise functions. It is found that both relativistic and 1/m_Q contributions significantly influence the decay rates. Thus, relativistic transformations of the meson wave functions (Wigner rotation of the light quark spin) already contribute at leading order of the heavy quark expansion and result in a suppression of B\to D^{*}_0e\nu and B\to D^{*}_1e\nu decay rates. On the other hand, the vanishing of the decay matrix elements at zero recoil of a final D^{**} meson in the infinitely heavy quark mass limit makes the 1/m_Q corrections to be very important, and their account results in a substantial enhancement of B\to D_1e\nu and B\to D^{*}_0e\nu decay rates.Exclusive semileptonic decays of B mesons to orbitally excited D mesons are considered beyond the infinitely heavy quark limit in the framework of the relativistic quark model based on the quasipotential approach. This model agrees with the structure of heavy quark mass corrections predicted by the heavy quark effective theory and allows the determination of corresponding leading and subleading Isgur-Wise functions. It is found that both relativistic and 1/m_Q contributions significantly influence the decay rates. Thus, relativistic transformations of the meson wave functions (Wigner rotation of the light quark spin) already contribute at leading order of the heavy quark expansion and result in a suppression of B\to D^{*}_0e\nu and B\to D^{*}_1e\nu decay rates. On the other hand, the vanishing of the decay matrix elements at zero recoil of a final D^{**} meson in the infinitely heavy quark mass limit makes the 1/m_Q corrections to be very important, and their account results in a substantial enhancement of B\to D_1e\nu and B\to D^{*}_0e\nu decay rates

Radiative M1-decays of heavy-light mesons in the relativistic quark model

Radiative magnetic dipole decays of heavy-light vector mesons into pseudoscalar mesons V -> P\gamma are considered within the relativistic quark model. The light quark is treated completely relativistically, while for the heavy quark the 1/m_Q expansion is used. It is found that relativistic effects result in a significant reduction of decay rates. Comparison with previous predictions and recent experimental data is presented.Comment: 11 pages, 2 figures, few comments added, version to appear in Phys. Lett.

Strong decays of vector mesons to pseudoscalar mesons in the relativistic quark model

AbstractStrong decays of vector (S13) mesons to the pair of pseudoscalar (S01) mesons are considered in the framework of the microscopic decay mechanism and the relativistic quark model based on the quasipotential approach. The quark–antiquark potential, which was previously used for the successful description of meson spectroscopy and electroweak decays, is employed as the source of the qq¯ pair creation. The relativistic structure of the decay matrix element, relativistic contributions and boosts of the meson wave functions are comprehensively taken into account. The calculated rates of strong decays of light, heavy-light mesons and heavy quarkonia agree well with available experimental data

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

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.

Relativistic Description of Exclusive Semileptonic Decays of Heavy Mesons

Using quasipotential approach, we have studied exclusive semileptonic decays of heavy mesons with the account of relativistic effects. Due to more complete relativistic description of the $s$ quark more precise expressions for semileptonic form factors are obtained. Various differential distributions in exclusive semileptonic decays of heavy mesons are calculated. It is argued that consistent account of relativistic effects and HQET motivated choice of the parameters of quark-antiquark potential allow to get reliable value for the ratio $A_2(0)/A_1(0)$ in the $D\to K^*l\nu_l$ decay as well as the ratio~$\Gamma(D\to K^*l\nu_l)/\Gamma(D\to Kl\nu_l)$. All calculated branching ratios are in accord with available experimental data.Comment: 18 pages, LATEX, 2 figures inclosed + 4 Postscript figure

Rare radiative B decay to the orbitally excited K_2^*(1430) meson

The exclusive rare radiative B meson decay to the orbitally excited tensor K_2^*(1430) meson is investigated in the framework of the relativistic quark model based on the quasipotential approach in quantum field theory. The calculated branching ratio BR(B --> K_2^*(1430)\gamma)=(1.7\pm 0.6)\times 10^{-5} as well as the ratio BR(B --> K_2^*(1430)\gamma)/BR(B --> K^*(892)\gamma)=0.38\pm 0.08 is found in a good agreement with recent experimental data from CLEO.Comment: 10 pages, RevTe

Form factors of heavy-to-light B decays at large recoil

General relations between the form factors of B decays to light mesons are derived using the heavy quark and large recoil expansion. On their basis the complete account of contributions of second order in the ratio of the light meson mass to the large recoil energy is performed. Both ground and excited final meson states are considered. It is shown that most of the known form factor relations remain valid after the inclusion of quadratic mass corrections. The validity of some of such relations requires additional equalities for the helicity amplitudes. It is found that all these relations and equalities are fulfilled in the relativistic quark model based on the quasipotential approach in quantum field theory. The contribution of 1/m_b corrections to the branching fraction of the rare radiative B decay is discussed.Comment: 23 pages, revte

Charm mass corrections to the bottomonium mass spectrum

The one-loop corrections to the bottomonium mass spectrum due to the finite charm mass are evaluated in the framework of the relativistic quark model. The obtained corrections are compared with the results of perturbative QCD.Comment: 6 pages, references added, version to be published in Phys. Rev.