A novel density of state method for complex action systems

Abstract

Recently, a new and efficient algorithm (the LLR method) has been proposed for computing densities of states in statistical systems and gauge theories. In this talk, we explore whether this novel density of states method can be applied to numerical computations of observables in systems for which the action is complex. To this purpose, we introduce a generalised density of states, in terms of which integrals of oscillating observables can be determined semi-analytically, and we define a strategy to compute it with the LLR method. As a case study, we apply these ideas to the Z(3) spin model at finite density, finding a remarkable agreement of our results for the phase twist with those obtained with the worm algorithm for all explored chemical potentials, including values for which there are cancellations over sixteen orders of magnitude. These findings open new perspectives for dealing with the sign problem on physically more relevant systems.

7 pages, 2 figures, contribution presented by B. Lucini at Lattice 2014

References in corpus (8)

• A study of the 't Hooft loop in SU(2) Yang-Mills theory
• The density of states in gauge theories
• The density of states approach to dense quantum systems
• New proposal for numerical simulations of theta-vacuum like systems
• The QCD phase diagram according to the center group
• Worm algorithms for the 3-state Potts model with magnetic field and chemical potential
• Progress in numerical simulations of systems with a $\theta -$vacuum like term: The two and three-dimensional Ising model within an imaginary magnetic field
• Sampling the density of states

Cited by in corpus (3)

• Free energy of the self-interacting relativistic lattice Bose gas at finite density
• Density of states method for the Z(3) spin model
• Numerical methods for the sign problem in Lattice Field Theory