Running Coupling Constant from Position-Space Current-Current Correlation Functions in Three-Flavor Lattice QCD.

Area of Science:

• High Energy Physics
• Quantum Chromodynamics
• Lattice Field Theory

Background:

• The strong coupling constant (α_{s}) is a fundamental parameter in quantum chromodynamics (QCD).
• Precise determination of α_{s} is crucial for understanding the strong nuclear force and making predictions in high-energy physics.
• Previous determinations have varying uncertainties, necessitating improved calculations.

Purpose of the Study:

• To determine the coupling constant in three-flavor QCD, α_{s}^{MS[over ¯]}(μ), within a specific renormalization scale range.
• To calculate the QCD Λ parameter using a novel approach based on current-current correlation functions.
• To achieve a precision competitive with existing world averages.

Main Methods:

• Utilized gauge field configuration ensembles with O(a)-improved Wilson-clover fermions from the Coordinated Lattice Simulations (CLS) consortium.
• Employed a novel approach based on current-current correlation functions.
• Performed perturbative conversion to the QCD Λ parameter and matched to high-order perturbation theory.

Main Results:

• Determined the coupling constant α_{s}^{MS[over ¯]}(μ) for μ∈(1,2) GeV.
• Obtained the QCD Λ parameter for three flavors: Λ_{MS[over ¯]}^{N_{f}=3}=342±17 MeV.
• Achieved precision comparable to the Particle Data Group's world average.

Conclusions:

• The calculated Λ parameter is in agreement with the established world average.
• The novel methodology combined with state-of-the-art lattice simulations provides a precise determination.
• This work contributes a valuable, high-precision value for a fundamental parameter in QCD.