Perturbative QCD Correction to the $B\to \pi$ Transition Form Factor

Abstract

We report on the perturbative $O({\alpha }_s)$ correction to the light-cone QCD sum rule for the $B\to \pi$ 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.

Comments: 14 pages, 4 figures, Latex, epsfig