Charmed-Meson Decay Constants from Improved QCD Sum Rules

TL;DR

This paper introduces an improved QCD sum rule approach for calculating charmed-meson decay constants, validated through quantum mechanics models, and aligns theoretical predictions with lattice QCD and experimental results.

Contribution

It develops a novel dispersive QCD sum rule method with an unbiased quark-hadron duality implementation, enhancing the accuracy of decay constant predictions.

Findings

Sum rule modifications improve decay constant estimates.

Results align with lattice QCD and experimental data.

MS-bar scheme is optimal for heavy-quark mass definitions.

Abstract

The decay constants of the charmed heavy pseudoscalar D and D_s mesons are revisited within a recently developed novel approach to dispersive QCD sum rules which relies on an unprejudiced implementation of quark-hadron duality. The proposed modification of the conventional sum-rule techniques is assessed by applying our prescriptions to quantum mechanics, where exact solutions may be easily obtained by simply solving the Schr\"odinger equation. The very striking similarity of the extraction procedures of bound-state parameters in potential models and in QCD gives us great confidence in the reliability of our improvements of the sum-rule formalism and their applicability to hadron phenomenology. The implications of one's chosen definition of the heavy-quark masses are scrutinized and the MS-bar quark-mass scheme is identified as the optimal choice for our purposes. Our ideas turn out to reconcile QCD sum-rule predictions for the charmed-meson decay constants (which before tended to be markedly too low) with the findings of both lattice QCD and experiment.