Lattice Hamiltonian approach to the massless Schwinger model: precise extraction of the mass gap

TL;DR

This paper employs a Hamiltonian approach with a high-order strong coupling expansion and exact diagonalization to accurately determine the mass gap in the massless Schwinger model, achieving precision better than 10^{-6}%.

Contribution

It introduces a highly precise method for extracting the mass gap in the massless Schwinger model using a finite basis and continuum limit extrapolation.

Findings

Reproduces analytical ground state energy with high accuracy

Achieves mass gap calculations with precision better than 10^{-6}%

Demonstrates the effectiveness of the Hamiltonian approach for continuum limit extraction

Abstract

We present results of applying the Hamiltonian approach to the massless Schwinger model. A finite basis is constructed using the strong coupling expansion to a very high order. Using exact diagonalization, the continuum limit can be reliably approached. This allows to reproduce the analytical results for the ground state energy, as well as the vector and scalar mass gaps to an outstanding precision better than 10^{-6} %.