Baryon number Dirac spectrum in QCD.

The relation between the baryon number in QCD at nonzero chemical potential and the spectral density of the baryon number Dirac operator, &ggr;0{D + m), is examined. We show that extreme oscillations of the spectral density, caused by the QCD sign problem, are essential for the formation of the average baryon number when &mgr; > m_/2. We compute the oscillating region of the spectral density using chiral perturbation theory. The extreme oscillations have a microscopic period and are resolved using random matrix theory. [ABSTRACT FROM AUTHOR]