Finite density QCD with heavy quarks
  In the large fermion mass limit of QCD at finite density the structure of the partition function greatly simplifies and can be studied analytically. We show that, contrary to general wisdom, the phase of the Dirac determinant is relevant only at finite temperature and can be neglected for zero temperature fields. 
R. Aloisio, V. Azcoiti, G. Di Carlo, A. Galante, A.F. Grillo