arXiv subjects

Moses A. Schindler

Publications and source records attributed to Moses A. Schindler.

5 recordsLinked to original sources

arXiv2025

Exotic phases in finite-density $\mathbb{Z}_3$ theories

Lattice $\mathbb{Z}_3$ theories with complex actions share many key features with finite-density QCD including a sign problem and $CK$ symmetry. Complex $\mathbb{Z}_3$ spin and gauge models exhibit a generalized Kramers-Wannier duality mapping them onto chiral $\mathbb{Z}_3$ spin and gauge models, which are simulatable with standard lattice methods in large regions of parameter space. The Migdal-Kadanoff real-space renormalization group (RG) preserves this duality, and we use it to compute the approximate phase diagram of both spin and gauge $\mathbb{Z}_3$ models in dimensions one through four. Chiral $\mathbb{Z}_3$ spin models are known to exhibit a Devil's Flower phase structure, with inhomogeneous phases which can be thought of as $\mathbb{Z}_3$ analogues of chiral spirals. Out of the large class of models we study, we find that only chiral spin models and their duals have a Devil's Flower structure with an infinite set of inhomogeneous phases, a result we attribute to Elitzur's theorem. We also find that different forms of the Migdal-Kadanoff RG produce different numbers of phases, a violation of the expectation for universal behavior from a real-space RG. We discuss extensions of our work to $\mathbb{Z}_N$ models, SU($N$) models and nonzero temperature.

hep-ph↗

arXiv2021

Finite-density QCD, $\mathcal{PT}$ symmetry, and dual algorithms

Finite-density QCD and many other field theories with sign problems have a $\mathcal{PT}$-type symmetry. After a brief introduction to $\mathcal{PT}$-symmetric field theories, a real dual representation for $\mathcal{PT}$-symmetric scalar field theories with complex actions is derived. We show that $\mathcal{PT}$-symmetric field theories can exhibit exotic behavior, including sinusoidally modulated propagators, disorder lines, and spatially inhomogeneous pattern-forming phases. We discuss the interplay of duality, $\mathcal{PT}$-symmetry and pattern formation using a $ϕ^4$ model and $Z(N)$ spin model with sign problems as examples. These behaviors may occur in finite-density QCD and related models.

hep-lat↗

arXiv2021

Finite-density QCD, $\mathcal{PT}$ symmetry, and exotic phases

We study the phase structure of effective models of finite-density QCD using analytic and lattice simulation techniques developed for the study of non-Hermitian and $\mathcal{PT}$-symmetric QFTs. Finite-density QCD is symmetric under the combined operation of the charge and complex conjugation operators $\mathcal{CK}$, which falls into the class of so-called generalized $\mathcal{PT}$ symmetries. We show that $\mathcal{PT}$-symmetric quantum field theories can support patterned ground-state field configurations in the vicinity of a critical endpoint. We apply our methods to a lattice heavy quark model at nonzero chemical potential that displays patterning behavior for a range of parameters. We derive a simple approximate criterion for the formation of these patterns, which can be used with lattice results.

hep-lat↗

arXiv2021

$\mathcal PT$ symmetry, pattern formation, and finite-density QCD

A longstanding issue in the study of quantum chromodynamics (QCD) is its behavior at nonzero baryon density, which has implications for many areas of physics. The path integral has a complex integrand when the quark chemical potential is nonzero and therefore has a sign problem, but it also has a generalized $\mathcal PT$ symmetry. We review some new approaches to $\mathcal PT$-symmetric field theories, including both analytical techniques and methods for lattice simulation. We show that $\mathcal PT$-symmetric field theories with more than one field generally have a much richer phase structure than their Hermitian counterparts, including stable phases with patterning behavior. The case of a $\mathcal PT$-symmetric extension of a $ϕ^4$ model is explained in detail. The relevance of these results to finite density QCD is explained, and we show that a simple model of finite density QCD exhibits a patterned phase in its critical region.

hep-lat↗

arXiv2021

Universality of Pattern Formation

We study a $\mathcal PT$-symmetric scalar Euclidean field theory with a complex action, using both theoretical analysis and lattice simulations. This model has a rich phase structure that exhibits pattern formation in the critical region. Analytical results and simulations associate pattern formation with tachyonic instabilities in the homogeneous phase. Monte Carlo simulation shows that pattern morphologies vary smoothly, without distinct microphases. We suggest that pattern formation in this model may be regarded as a form of arrested spinodal decomposition. We extend our theoretical analysis to multicomponent $\mathcal PT$-symmetric Euclidean scalar field theories and show that they give rise to new universality classes of local field theories that exhibit patterned behavior in the critical region. QCD at finite temperature and density is a member of the $Z(2)$ universality class when the Polyakov loop is used to distinguish confined and deconfined phases. This suggests the possibility of the formation of patterns of confined and deconfined matter in QCD in the critical region in the $μ-T$ plane.

hep-lat↗