mixing in the HQET

Abstract

We present a high statistics, quenched lattice calculation of the B-parameters B B d and B Bs , computed at lowest order in the HQET. The results were obtained using a sample of 600 quenched gauge field configurations, generated by Monte Carlo simulation at β = 6.0 on a 24 3 × 40 lattice. For the light quarks the SW-Clover action was used; the propagator of the lattice HQET was also tree-level improved. Our best estimate of the renormalization scale independent B-parameter isB B d = 1.03 ± 0.06±0.18. B B d has been obtained by using "boosted" perturbation theory to calculate the renormalization constants which relate the matrix elements of the lattice operators to the corresponding amplitudes in the continuum. Due to the large statistics, the errors in the extraction of the matrix elements of the relevant bare operators are rather small. The main systematic error, corresponding to ±0.18 in the above result, comes from the uncertainty in the evaluation of the renormalization constants, for which the one-loop corrections are rather large. The non-perturbative evaluation of these constants will help to reduce the final error. We also obtainB Bs /B B d = 1.01 ± 0.01 and f 2 BsB Bs /f 2 B dB B d = 1.38 ± 0.07.

Width difference in the Bs0-Bs0 system from lattice HQET

“…So far, the complete chain of matching equations have been calculated for O L only. However, the two last steps are known for all operators [4,8,9]. We have extended the calculation to all the ∆B = 2 operators computing the continuum QCD -HQET matching and the two loop anomalous dimensions [10,11].…”

“…The lattice B-parameters are extracted from the large time behavior of the ratio between threeand two-point correlation functions (see for example [4]):…”

“…The results presented here are obtained from a quenched simulation performed by APE collaboration in a 24 3 × 40 lattice with 600 gauge configuration at β = 6.0 with a −1 = 2 Gev. The details of the simulation can be found in [4] and references therein.…”

“…This result has been obtained in static simulations by APE coll. [4], UKQCD coll. [12], Christensen et al [13] and also by JLQCD coll.…”

Quenched and first unquenched lattice HQET determination of the Bs-meson width difference

“…The lattice B-parameters are extracted from the large time behavior of the ratio between threeand two-point correlation functions (see [6]):…”