Perturbative QCD correction to the B->pi transition form factor

We report on the perturbative O(alpha(s)) correction to the light-cone QCD sum rule for the B --> pi transition form factor f(+). The correction to the product f(B)f(+) in leading twist approximation is found to be about 30%, that is similar in magnitude to the corresponding O(alpha(s)) correction in the two-point sum rule for f(B). The resulting cancellation of large QCD corrections in f(+) eliminates one important uncertainty in the sum-rule prediction for this form factor. (C) 1997 Elsevier Science B.V.