The Light-Front Coupled-Cluster Method Applied to ϕ1+14\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\phi_{1+1}^4}$$\end{document} Theory

We use the light-front coupled-cluster (LFCC) method to compute the odd-parity massive eigenstate of ϕ1+14\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\phi_{1+1}^4}$$\end{document} theory. A standard Fock-space truncation of the eigenstate yields a finite set of linear equations for a finite number of wave functions. The LFCC method replaces Fock-space truncation with a more sophisticated truncation; the eigenvalue problem is reduced to a finite set of nonlinear equations without any restriction on Fock space, but with restrictions on the Fock wave functions. We compare our results with those obtained with a Fock-space truncation.