HQET: Heavy Heavy vertex diagram with two velocities
Andrey Grozin (Novosibirsk State University)

The one-loop HQET heavy-heavy vertex diagram with arbitrary powers of all three denominators and arbitrary residual energies is investigated. This allows one to calculate this triangle diagram with arbitrary radiative corrections to all 3 propagators (2 heavy ones and 1 massless) (provided that there are no loops of finite-mass quarks). Various cases when the result becomes simpler are considered.