Zero modes in the light-front coupled-cluster method

TL;DR

This paper extends the light-front coupled-cluster method to include zero modes, enabling the study of vacuum structure and non-trivial states in light-front quantum field theories.

Contribution

It introduces a way to incorporate zero modes into the LFCC method, allowing for the analysis of vacuum structure in light-front field theories.

Findings

Zero modes enable non-trivial vacuum states in the LFCC framework.

The method models vacuum structure as a generalized coherent state of zero modes.

Application demonstrated in two-dimensional model field theories.

Abstract

The light-front coupled-cluster (LFCC) method is a technique for solving Hamiltonian eigenvalue problems in light-front-quantized field theories. Its primary purpose is to provide a systematic sequence of solvable approximations to the original eigenvalue problem without the truncation of Fock space. Here we discuss the incorporation of zero modes, modes of zero longitudinal momentum, into the formalism of the method. Without zero modes, the light-front vacuum is trivial, and the vacuum expectation value of the field is always zero. The LFCC method with zero modes provides for vacuum structure, in the form of a generalized coherent state of zero modes, as is illustrated here in two-dimensional model field theories.