Relativistic corrections to the axial vector and vector currents in the barbc meson system at order alphaₛ

Original · EN

We compute the short distance coefficients for the NRQCD factorization formulas of the meson-to-vacuum matrix elements for the axial vector and vector parts of the charged weak current in the S-wave spin-singlet and -triplet barbc mesons, respectively. The computation is carried out to order alphaₛ including relativistic corrections of all orders in vecq²ⁿ, where vecq is the relative momentum of the barb and c in the meson rest frame. The relativistic corrections at order alphaₛ are new. The results reveal that the relativistic corrections to the leptonic decay rate of the Bc meson at order alphaₛ or less converge rapidly, which shows a strong contrast to the uncomfortably large corrections of order alphaₛ²|vecq|⁰. The short distance coefficients listed in this paper can be employed to compute the resummation of relativistic corrections to the phenomenological measurables that involve Bc and Bc* production and decay.