Do two ways of calculating rare B meson decays agree?

Rare decays of B_c mesons involve intricate quantum interference between soft quarks and gluons. The authors verify that two different theoretical approaches—one using SCET (a modern effective theory) and another using integral equations—give identical predictions for how these decays proceed. This three-loop consistency check is crucial because it validates the approximations needed to make otherwise intractable calculations tractable.