Semi-Leptonic b-decay at Intermediate Recoil

Understand

We compute the O(\alpha_s^2) corrections to the differential rate of the semileptonic decay b -> clv at the "intermediate recoil" point, where the c-quark mass and the invariant mass of the leptons are equal.

• The calculation is based on an expansion around two opposite limits of the quark masses m_{b,c}: m_c ~ m_b and m_c << m_b.
• The former case was previously studied; we correct and extend that result.
• The latter case is new.