New QCD Sum Rules for Nucleon Axial Vector Coupling Constants

Abstract

Two new sets of QCD sum rules for the nucleon axial coupling constants are derived using the external-field technique and generalized interpolating fields. An in-depth study of the predicative ability of these sum rules is carried out using a Monte-Carlo based uncertainty analysis. The results show that the standard implementation of the QCD sum rule method has only marginal predicative power for the nucleon axial coupling constants, as the relative errors are large. The errors range from approximately 50 to 100% compared to the nucleon mass obtained from the same method, which has only 10% to 25% error. The origin of the large errors is examined. Previous analyses of these coupling constants are based on sum rules that have poor OPE convergence and large continuum contributions. Preferred sum rules are identified and their predictions are obtained. We also investigate the new sum rules with an alternative treatment of the problematic transitions which are not exponentially suppressed in the standard treatment. The new treatment provides exponential suppression of their contributions relative to the ground state. Implications for other nucleon current matrix elements are also discussed.

30 pages in RevTeX with 11 PS figures embedded. A brief conference contribution appeared earlier in nucl-th/9606026

References in corpus (7)

• QCD Sum Rules for Skeptics
• The Nucleon's Tensor Charge
• Valid QCD Sum Rules for Vector Mesons in Nuclear Matter
• New QCD Sum Rules for Nucleons in Nuclear Matter
• Background-Field Formalism in Quantum Systems
• Rho-Omega Mixing via QCD Sum Rules with Finite Mesonic Widths
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• A comprehensive revisit of the $\rho$ meson with improved Monte-Carlo based QCD sum rules
• Finite-width effects on Delta baryons in QCD Sum Rules
• New QCD Sum Rules for Nucleon Tensor Charge
• Chirality and Reliability of Baryon QCD Sum Rules
• Spin Content of Lambda in QCD Sum Rules