Lattice QCD at Finite Isospin Density

QCD at finite temperature and density describes the physics of the early Universe, neutron stars, heavy nuclei, and relativistic heavy ion collisions. Nuclear matter exists not only at finite baryon number, but also at finite negative isospin (I₃) density. QCD at finite chemical potential _I for I₃ has a positive fermion determinant and thus can be simulated using hybrid molecular dynamics methods.

	Figure 5   The pion condensate as a function of I.

Kogut and Sinclair have simulated QCD at zero temperature, = 5.2, and finite _I on 8⁴ lattices at quark mass m = 0.025 and m = 0.05 with a small symmetry breaking parameter, l. Preliminary results suggest that for _I > _c , this theory forms a charged pion concentrate (Figure 5) which spontaneously breaks I₃, and the isospin density is non zero. Simulations planned for FY2003 will extend this to a 12³ x 24 lattice, allowing measurement of the mass of the Goldstone pion that this symmetry breaking implies, measurement of the spectrum of pseudo-Goldstone bosons, and confirmation of the nature of the transition.

INVESTIGATORS
D. K. Sinclair, Argonne National Laboratory; J. B. Kogut, University of Illinois.

PUBLICATION
J. B. Kogut and D. K. Sinclair, “Lattice QCD at finite isospin density,” Nucl. Phys. B Proc. Suppl. 106, 444 (2002).

URL
http://www.hep.anl.gov/dks/NERSC2002/