# Convergent series for polynomial lattice models with complex actions

## TL;DR

This paper introduces a novel convergent series method with a non-Gaussian initial approximation to address the sign problem in lattice models with complex actions, demonstrated on a 2D oscillating integral.

## Contribution

It develops a new convergent series approach for complex action lattice models, extending previous methods with a non-Gaussian starting point.

## Key findings

- Successfully applied to a 2D oscillating integral
- Avoids the sign problem in complex action models
- Demonstrates potential for finite density matter studies

## Abstract

Lattice models with complex actions are important for the understanding of matter at finite densities, but not accessible by the standard Monte Carlo techniques due to the sign problem. Here we derive a new approach for avoiding the complex action/sign problem, by extending the method of convergent series with a non-Gaussian initial approximation. The main features of the new series are demonstrated on the example of the two dimensional oscillating integral.