FINITE BARYON DENSITY IN LATTICE SIMULATIONS AND NUCLEAR-MATTER

A simple model for the partition function of an interacting nucleon gas can explain the early onset of the baryon density observed when using staggered fermions on the lattice at finite chemical potential. The onset, which is very sensitive to the number of lightest nucleon states formed, represents the point where condensation into nuclear matter occurs. The lattice simulations have been done with staggered fermions or 4 degenerate valence quarks, which can bind into 40 lightest nucleons for which the model can fit the early onset as found on the lattice for various quark masses. The statistical model contains scalar interactions, producing attractive energies scaling as m(N)-2, among nucleons which propagate in effective volumes that exclude the hard nucleon cores determined by m(omega). Extrapolating the number of flavours and masses to the values in nature, where we have 4 lowest nucleon states, the model shows an onset close to the nucleon mass as desired.