Sign problem in finite density lattice QCD

Nov 24, 2016
7 pages
Published in:
  • PTEP 2017 (2017) 3, 031D01
  • Published: Mar 1, 2017
e-Print:

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Abstract: (Oxford University Press)
The canonical approach, which was developed for solving the sign problem, may suffer from a new type of sign problem. In this method, the grand partition function is written as a fugacity expansion: ZG(μ,T)=nZC(n,T)ξnZ_G(\mu,T) = \sum_n Z_C(n,T) \xi^n, where ξ=exp(μ/T)\xi=\exp(\mu/T) is the fugacity, and ZC(n,T)Z_C(n,T) are given as averages over a Monte Carlo update, zn\langle z_n\rangle. We show that the complex phase of znz_n is proportional to nn at each Monte Carlo step. Although zn\langle z_n\rangle take real positive values, the values of znz_n fluctuate rapidly when nn is large, especially in the confinement phase, which gives a limit on nn. We discuss a mechanism of phase emergence.
Note:
  • 7 pages, 6 figures
  • D31
  • D34
  • D31 Quark-gluon plasma
  • D34 Lattice QCD calculations in nuclear physics
  • density: finite
  • potential: chemical
  • numerical calculations: Monte Carlo
  • quantum chromodynamics: lattice
  • partition function
  • fluctuation