文章基本信息

标题：Sign problem in two-color two-flavor QCD with quark and isospin chemical potentials
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作者：K. Fukushima
期刊名称：PoS - Proceedings of Science
印刷版ISSN：1824-8039
出版年度：2007
出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：We revisit two-color two-flavor Quantum Chromodynamics (QCD) which suffers from the sign problem of the Dirac determinant at finite baryon or quark density if a finite isospin chemical potential breaks two-flavor degeneracy. We discuss the eigenvalue distribution of the single-flavor Dirac operator to find the quartet structure, i.e. if l +m is an eigenvalue where m is the current quark mass in a continuum theory, l ¤ +m, ¡l +m, and ¡l ¤ +m must be eigenvalues as well. As a result the product of these four eigenvalues makes a non-negative real number, unless l is real. The sign problem remains harmful for real l because not a quartet but a pair of l +m and ¡l +m appears then and its product is not necessarily non-negative. In such a case, however, the sign problem has a different nature from the ordinary one in three-color QCD at finite density. We can rather identify it as the sign problem in the parity broken (or Aoki) phase inherent in the Wilson fermion formalism.