Relativistic description of exclusive heavy-to-light semileptonic decays {ital B}{r_arrow}{pi}({rho}){ital e}{nu}
- Russian Academy of Sciences, Scientific Council for Cybernetics, Vavilov Street 40, Moscow 117333 (Russia)
The method of calculating electroweak decay matrix elements between heavy-heavy and heavy-light meson states is developed in the framework of a relativistic quark model based on the quasipotential approach in quantum field theory. This method is applied to the study of exclusive semileptonic {ital B}{r_arrow}{pi}({rho}) decays. It is shown that the large value of the final {pi}({rho}) meson recoil momentum allows for the expansion in inverse powers of the {ital b}-quark mass of the decay form factors at {ital q} {sup 2}=0, where {ital q} is a momentum carried by the lepton pair. This 1/{ital m}{sub {ital b}} expansion considerably simplifies the analysis of these decays and is carried out up to the second order. The {ital q}{sup 2} dependence of the form factors is investigated. It is found that the {ital q}{sup 2} behavior of the axial form factor {ital A}{sub 1} is different from the other form factors. It is argued that the ratios {Gamma}({ital B}{r_arrow}{rho}{ital e}{nu})/{Gamma}({ital B}{r_arrow}{pi}{ital e}{nu}) and {Gamma}{sub {ital L}}/{Gamma}{sub {ital T}} are sensitive probes of the {ital A}{sub 1} {ital q}{sup 2} dependence, and, thus, their experimental measurement may discriminate between different approaches. We find {Gamma}({ital B}{r_arrow}{pi}{ital e}{nu})=(3.0{plus_minus}0.6){times}{parallel}{ital V}{sub {ital ub}}{parallel}{sup 2}{times}10{sup 12}s{sup {minus}1 &} and {Gamma}({ital B}{r_arrow}{rho}{ital e}{nu})=(5.4{plus_minus}1.2){times}{parallel}{ital V}{sub {ital ub}}{parallel}{sup 2}{times}10{sup 12}s{sup {minus}1 &u}. The relation between semileptonic and rare radiative {ital B} decays is discussed. {copyright} {ital 1996 The American Physical Society.}
- OSTI ID:
- 284576
- Journal Information:
- Physical Review, D, Vol. 53, Issue 11; Other Information: PBD: Jun 1996
- Country of Publication:
- United States
- Language:
- English
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