Lattice QCD study of mixed systems of pions and kaons

TL;DR

This study uses lattice QCD to analyze the ground state energies and interactions of mixed pion and kaon systems, revealing phase transition regions consistent with theoretical predictions.

Contribution

It provides new lattice QCD calculations of multi-meson systems with mixed pions and kaons, exploring their interactions and phase transitions.

Findings

Ground state energies of N-pion and M-kaon systems computed

Two- and three-body interactions extracted from energies

Identification of phase transition regions between pion and kaon condensation

Abstract

The different ground state energies of N-pion and M-kaon systems for N+M <=12 are studied in lattice QCD. These energies are then used to extract the various two- and three- body interactions that occur in these systems. Particular attention is paid to additional thermal states present in the spectrum because of the finite temporal extent. These calculations are performed using one ensemble of 2+1 flavor anisotropic lattices with a spatial lattice spacing a_s ~ 0.125 fm, an anisotropy factor {\xi}=a_s/a_t=3.5, and a spatial volume L^3 ~ (2.5 fm)^3. The quark masses used correspond to pion and kaon masses of m_{\pi} ~ 383 MeV and m_K ~ 537 MeV, respectively. The isospin and strangeness chemical potentials of these systems are found to be in the region where chiral perturbation theory and hadronic models predict a phase transition between a pion condensed phase and a kaon condensed phase.