STATUS OF THE B_(S)~0-B_(S)~0 MIXING FROM QCD SPECTRAL SUM RULES

摘要

In this talk, I summarize new results obtained from QCD spectral sum rules (QSSR), on the bag constant parameters entering in the analysis of the B_(S)~0-B_(S)~0 mass-differences. Taking the average of the results from the Laplace and moment sum rules, one obtains to order α_s: f_B (B_B)~(1/2) approx= (229 +-55) GeV, f_(B_s) (B_(B_s)~(1/2)/f_B (B_B)~(1/2) approx= 1.18 +- 0.03, in units where f_π = 130.7 MeV. Combined with the experimental data on the mass-differences ΔM_(d,s), one obtains the constraint on the CKM weak mixing angle: |V_(ts)/V_(td)|~2 ≥ 20.2(1.3). Alternatively, using the weak mixing angle from the analysis of the unitarity triangle and the data on ΔM_d, one predicts ΔM_s = 18.3(2.1) ps~(-1) in agreement with the present experimental lower bound and within the reach of Tevatron 2.