Phase of the Fermion Determinant at Nonzero Chemical Potential

Splittorff, K.; Verbaarschot, J. J. M.

Phase of the Fermion Determinant at Nonzero Chemical Potential

Authors

Description

We show that in the microscopic domain of QCD (also known as the $ε$-domain) at nonzero chemical potential the average phase factor of the fermion determinant is nonzero for $μ< m_π/2$ and is exponentially suppressed for larger values of the chemical potential. This follows from the chiral Lagrangian that describes the low-energy limit of the expectation value of the phase factor. Explicit expressions for the average phase factor are derived using a random matrix formulation of the zero momentum limit of this chiral Lagrangian.
4 pages, 1 figure