Fermion Bag Approach to Fermion Sign Problems

TL;DR

The paper introduces the fermion bag approach, a novel method that transforms the way fermion sign problems are addressed in lattice field theories, enabling Monte Carlo solutions for previously intractable models.

Contribution

It presents a new fermion bag method that reveals hidden pairing mechanisms, solving certain fermion sign problems and expanding the scope of Monte Carlo simulations in strongly correlated systems.

Findings

Enables Monte Carlo simulations of previously unsolvable fermion models.

Reveals hidden pairing mechanisms in fermion systems.

Provides a new framework for tackling fermion sign problems.

Abstract

The fermion bag approach is a new method to tackle fermion sign problems in lattice field theories. Using this approach it is possible to solve a class of sign problems that seem unsolvable by traditional methods. The new solutions emerge when partition functions are written in terms of fermion bags and bosonic worldlines. In these new variables it is possible to identify hidden pairing mechanisms which lead to the solutions. The new solutions allow us for the first time to use Monte Carlo methods to solve a variety of interesting lattice field theories, thus creating new opportunities for understanding strongly correlated fermion systems.