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Evidence for instanton-induced dynamics from lattice QCD.
Pietro Faccioli1, Thomas A DeGrand
1E.C.T., Strada delle Tabarelle 286, I-38050 Villazzano (Trento), Italy. faccioli@ect.it
Physical Review Letters
|November 13, 2003
Summary
This study reveals large scalar and pseudoscalar components in the nonperturbative quark-quark interaction within Quantum Chromodynamics (QCD). Lattice QCD results quantitatively match the instanton liquid model, explaining unitarity loss when quark loops are suppressed.
Area of Science:
- Quantum Chromodynamics (QCD)
- Lattice Gauge Theory
- Hadron Physics
Background:
- Understanding the nonperturbative dynamics of the light-quark sector of QCD is crucial for describing hadron properties.
- Lattice simulations with chiral fermions provide a powerful tool for investigating these complex interactions.
Purpose of the Study:
- To analyze the Dirac structure of the quark-quark interaction in the nonperturbative regime.
- To compare lattice QCD results with theoretical models like the instanton liquid model.
- To investigate the impact of suppressed quark loops on quark-quark interactions.
Main Methods:
- Analysis of correlators designed to probe quark-quark interactions.
- Utilizing recent lattice QCD simulation results with chiral fermions.
- Comparison with predictions from the instanton liquid model and Dyson-Schwinger equations (DSE) approaches.
Main Results:
- The quark-quark interaction in the nonperturbative regime exhibits significant scalar and pseudoscalar components.
- Quantitative agreement was found between lattice QCD data and the instanton liquid model.
- Suppression of quark loops leads to a dramatic loss of unitarity, naturally explained by the instanton picture.
Conclusions:
- The instanton liquid model provides a successful description of nonperturbative quark-quark interactions in QCD.
- Standard Dyson-Schwinger equation approaches with vector coupling may not fully capture these nonperturbative effects, particularly the loss of unitarity.