Conjectures about the Chiral Phase Transition in QCD from Anomalous Multi-Instanton Interactions

Area of Science:

• Theoretical and Computational Physics
• High-Energy Physics
• Quantum Chromodynamics (QCD)

Background:

• Lattice QCD simulations have not yet confirmed the expected first-order chiral phase transition for light pions.
• The anomalous U_{A}(1) symmetry in QCD is known to be broken, even in the chirally symmetric phase.

Purpose of the Study:

• To investigate the relationship between the restoration of exact global chiral symmetry and the breaking of the anomalous U_{A}(1) symmetry in QCD.
• To identify new, testable signals for lattice QCD simulations related to U_{A}(1) symmetry breaking.

Main Methods:

• Theoretical analysis of chiral symmetry restoration in QCD.
• Exploration of the impact on anomalous U_{A}(1) symmetry breaking.
• Proposal for lattice QCD simulations with varying numbers of flavors (one to four).

Main Results:

• The restoration of exact global chiral symmetry can significantly reduce the breaking of the approximate, anomalous U_{A}(1) symmetry.
• This reduction is predicted to be observable in lattice simulations.

Conclusions:

• The interplay between chiral symmetry and U_{A}(1) symmetry breaking offers new avenues for understanding QCD.
• Novel experimental signals are predicted in the chirally symmetric phase due to residual U_{A}(1) breaking, testable via lattice QCD.