Numerical portrait of a relativistic BCS gapped superfluid
Abstract
We present results of numerical simulations of the (3+1)dimensional Nambu JonaLasinio model with a nonzero baryon density enforced via the introduction of a chemical potential μ≠0. The triviality of the model with a number of dimensions d⩾4 is dealt with by fitting low energy constants, calculated analytically in the large number of colors (Hartree) limit, to phenomenological values. Nonperturbative measurements of local order parameters for superfluidity and their related susceptibilities show that, in contrast with the (2+1)dimensional model, the ground state at high chemical potential and low temperature is that of a traditional BCS superfluid. This conclusion is supported by the direct observation of a gap in the dispersion relation for 0.5⩽μa⩽0.85, which at μa=0.8 is found to be roughly 15% the size of the vacuum fermion mass. We also present results of an initial investigation of the stability of the BCS phase against thermal fluctuations. Finally, we discuss the effect of splitting the Fermi surfaces of the pairing partners by the introduction of a nonzero isospin chemical potential.
 Publication:

Physical Review D
 Pub Date:
 April 2004
 DOI:
 10.1103/PhysRevD.69.076011
 arXiv:
 arXiv:heplat/0401018
 Bibcode:
 2004PhRvD..69g6011H
 Keywords:

 11.30.Fs;
 11.15.Ha;
 21.65.+f;
 Global symmetries;
 Lattice gauge theory;
 Nuclear matter;
 High Energy Physics  Lattice;
 High Energy Physics  Phenomenology;
 Nuclear Theory
 EPrint:
 41 pages, 19 figures, uses axodraw.sty, v2: minor typographical corrections