Relativistic description of exclusive semileptonic decays of heavy mesons

Using the quasipotential approach, we study exclusive semileptonic decays of heavy mesons taking into account relativistic effects. Because of a 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 a consistent account of relativistic effects and a heavy quark effective theory motivated choice of the parameters of the quark-antiquark potential allow one to get a reliable value for the ratio ${\mathit{A}}_2$(0)/${\mathit{A}}_1$(0) in the D→${\mathit{K}}^{\mathrm{*}}$l${\nu }_{\mathit{l}}$ decay as well as the ratio Γ(D→${\mathit{K}}^{\mathrm{*}}$l${\nu }_{\mathit{l}}$)/Γ(D→Kl${\nu }_{\mathit{l}}$). All calculated branching ratios are in accord with available experimental data. © 1996 The American Physical Society.