Precision for B-meson matrix elements

Abstract

We demonstrate how HQET and the Step Scaling Method for B-physics, pioneered by the Tor Vergata group, can be combined to reach a further improved precision. The observables considered are the mass of the b-quark and the B_s-meson decay constant. The demonstration is carried out in quenched lattice QCD. We start from a small volume, where one can use a standard O(a)-improved relativistic action for the b-quark, and compute two step scaling functions which relate the observables to the large volume ones. In all steps we extrapolate to the continuum limit, separately in HQET and in QCD for masses below m_b. The physical point m_b is then reached by an interpolation of the continuum results in 1/m. The essential, expected and verified, feature is that the step scaling fuctions have a weak mass-dependence resulting in an easy interpolation to the physical point. With r_0=0.5fm and the experimental B_s and K masses as input, we find F_Bs=191(6)MeV and the renormalization group invariant mass M_b=6.88(10)GeV, translating into m_b(m_b)=4.42(6)GeV in the MSbar scheme. This approach seems very promising for full QCD.

16 pages all included

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Cited by in corpus (8)

• Studies of Nucleon Resonance Structure in Exclusive Meson Electroproduction
• A proposal for B-physics on current lattices
• Non-perturbative improvement of quark mass renormalization in two-flavour lattice QCD
• Calculation of binding energies and masses of quarkonia in analytic QCD models
• The b-quark mass from non-perturbative $N_f=2$ Heavy Quark Effective Theory at $O(1/m_h)$
• Quenched lattice calculation of the vector channel B --> D* l nu decay rate
• Heavy quark masses from lattice QCD
• Heavy-strange meson decay constants in the continuum limit of quenched QCD