QSSR estimate of the $B_B$ parameter at next-to-leading order

Abstract

We compute the leading ${\alpha }_s$ corrections to the two-point correlator of the $O_{\Delta B=2}$ operator which controls the $B^0{\bar{B}}^0$ mixing. Using this result within the QCD spectral sum rules approach and some phenomenologically reasonable assumptions in the parametrization of the spectral function, we conclude that the vacuum saturation values $B_B\simeq B_{B^{\ast }}\simeq 1$ are satisfied within 15\%.

Comments: 8 pages, LaTeX, CERN-TH.7140/94, PM 93/16, and KEK Preprint 93-184, two figures appended as a PS file