We investigate the singularity structure of the (-1)F graded partition function in QCD with nf≥1 massive adjoint fermions in the large-N limit. Here, F is fermion number and N is the number of colors. The large N partition function is made reliably calculable by taking space to be a small three-sphere S3. Singularities in the graded partition function are related to phase transitions and to Hagedorn behavior in the (-1)F-graded density of states. We study the flow of the singularities in the complex "inverse temperature" β plane as a function of the quark mass. This analysis is a generalization of the Lee-Yang-Fisher-type analysis for a theory which is always in the thermodynamic limit thanks to the large N limit. We identify two distinct mechanisms for the appearance of physical Hagedorn singularities and center-symmetry changing phase transitions at real positive β, inflow of singularities from the β=0 point, and collisions of complex conjugate pairs of singularities.
Bibliographical noteFunding Information:
We are grateful to O. Costin for helpful discussions. The work of S. K., T. S. and M. Ü. is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Award Number DE-FG02-03ER41260.
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