Multipion systems in lattice QCD and the three-pion interaction

Area of Science:

• High Energy Physics
• Quantum Chromodynamics
• Particle Interactions

Background:

• Understanding multi-pion interactions is crucial for particle physics.
• Lattice Quantum Chromodynamics (QCD) provides a computational framework for studying these interactions.

Purpose of the Study:

• To compute ground-state energies of multiple positive pions (π+) in a finite spatial volume.
• To precisely extract the pion-pion scattering length by accounting for three-pion interactions.
• To investigate the nature of the three-pion interaction.

Main Methods:

• Lattice Quantum Chromodynamics (QCD) simulations were performed.
• Ground-state energies for 2, 3, 4, and 5 positive pions were calculated in a volume of approximately (2.5 fm)³.
• Specific combinations of energies were used to isolate and analyze pion-pion and three-pion interactions.

Main Results:

• Precise extractions of the pion-pion scattering length were achieved, consistent with previous two-pion calculations.
• The leading contribution from three-pion interactions was successfully eliminated.
• A repulsive three-pion interaction was identified for pion masses around 352 MeV.

Conclusions:

• The study successfully demonstrates a method to precisely determine scattering lengths in the presence of multi-pion interactions.
• The findings provide evidence for a repulsive three-pion force, contributing to the understanding of fundamental particle interactions.