Heavy-Quark Mass and Heavy-Meson Decay Constants from QCD Sum Rules

TL;DR

This paper uses QCD sum rules with a novel Borel-parameter-dependent dual threshold method to accurately extract heavy-meson decay constants, controlling uncertainties from input parameters and method limitations.

Contribution

It introduces a new procedure for extracting hadron observables from QCD sum rules that improves uncertainty control and provides precise decay constant estimates.

Findings

Accurate decay constants for D and D_s mesons.

Precise determination of b-quark mass m_b(m_b) as 4.245 GeV.

Decay constants for B and B_s mesons consistent with lattice results.

Abstract

We present a sum-rule extraction of heavy-meson decay constants from the two-point correlator of heavy-light pseudoscalar currents. Our main concern is to control the uncertainties of the decay constants, induced by both input QCD parameters and limited accuracy of the sum-rule method. Gaining this control is possible by applying our novel procedure for the extraction of hadron observables utilizing Borel-parameter-depending dual thresholds. For the charmed mesons, we obtain f_D = 206.2 \pm 7.3 (OPE) \pm 5.1 (syst) MeV and f_{D_s} = 245.3 \pm 15.7 (OPE) \pm 4.5 (syst) MeV. For the beauty mesons, the decay constants prove to be extremely sensitive to the exact value of the b-quark MS-bar mass m_b(m_b). Matching our sum-rule prediction for f_B to the lattice findings, the very accurate b-mass value m_b(m_b) = 4.245 \pm 0.025 GeV is found, which yields f_B = 193.4 \pm 12.3 (OPE) \pm 4.3 (syst) MeV and f_{B_s} = 232.5 \pm 18.6 (OPE) \pm 2.4 (syst) MeV.