Heavy quark 1/m_Q contributions in semileptonic B decays to orbitally excited D mesons

TL;DR

This paper analyzes semileptonic B decays to orbitally excited D mesons beyond the heavy quark limit, highlighting the significant impact of relativistic and 1/m_Q corrections on decay rates within a relativistic quark model.

Contribution

It introduces a relativistic quark model that incorporates heavy quark mass corrections and determines Isgur-Wise functions, revealing the importance of relativistic and 1/m_Q effects on decay rates.

Findings

Relativistic effects suppress certain decay rates.

1/m_Q corrections significantly enhance other decay rates.

Both effects are crucial for accurate decay rate predictions.

Abstract

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.