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# 36th Annual International Symposium on Lattice Field Theory

Jul 22 – 28, 2018
Kellogg Hotel and Conference Center
EST timezone

## Simulation of Scalar Field Theories with Complex Actions

Jul 24, 2018, 4:10 PM
20m
Centennial (Kellogg Hotel and Conference Center)

### Centennial

#### Kellogg Hotel and Conference Center

219 S Harrison Rd, East Lansing, MI 48824
Nonzero Temperature and Density

### Speaker

Prof. Michael Ogilvie (Washington University in St. Louis)

### Description

Many scalar field theory models with complex actions are invariant under the antilinear ($\mathcal{PT}$) symmetry operation $L^{*}(-\chi)=L(\chi)$. Models in this class include $i \phi^3$, the Bose gas at finite density and Polyakov loop spin models at finite density. This symmetry may be used to obtain a dual representation where weights in the functional integral are real but not necessarily positive. For a subclass of models satisfying a dual positive weight condition, the sign problem is absent; such models are easily simulated by a simple local algorithm in any number of dimensions. The existence of a positive representation is constrained by Lee-Yang zeros, and tied to the phase structure of a given model. Simulations of models in this subclass show a rich set of behaviors. Propagators may exhibit damped oscillations, indicating a clear violation of spectral positivity. Domain patterns may occur in equilibrium, with both stripe and bubble morphologies occurring. These behaviors appear to be likely in finite density QCD in the vicinity of the critical line.

### Primary author

Prof. Michael Ogilvie (Washington University in St. Louis)

### Co-author

Dr Leandro Medina (Washington University in St. Louis)

 Slides