2011/09/29 by Masanori Hanada, Hanada, Masanori
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Lattice (hep-lat) #High Energy Physics - Theory (hep-th) #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-lat #hep-th
paper · pdf · doi:10.48550/arxiv.1109.6372
Slightly modified version of the article submitted to Seitaro Nakamura competition. 23 pages, 9 figures. v2: 25 pages, 9 figures
openalex publication_date 2011/09/29 · arxiv created 2012/09/25 · arxiv updated 2012/09/26 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
QCD with a finite baryon chemical potential, despite its importance, is not well understood because the standard lattice QCD simulation is not applicable due to the sign problem. Although QCD-like theories which do not suffer from the sign problem have been studied intensively, relation to QCD with a finite baryon chemical potential was not clear. This paper introduces large-Nc equivalences between QCD and various QCD-like theories. These equivalences lead us to a unified viewpoint for QCD with baryon and isospin chemical potentials, SO(2Nc) and Sp(2Nc) gauge theories, QCD with adjoint matters and two-color QCD. In particular QCD with the baryon chemical potential is large-Nc equivalent to its phase quenched version in a certain parameter region, which is relevant for heavy ion collision experiments. All previous simulation results which study the effect of the phase confirm the phase quench approximation is quantitatively good already at Nc=3; it is so good that often two theories give the same value within error. Therefore the phase quenched simulation is the best strategy for the QCD critical point search. At small volume one can study a tiny 1/Nc effect by the phase reweighting; the large-Nc equivalence guarantees that the phase reweighing method works without suffering from the overlapping problem.