1998/06/15 by N. C. J. Schoonderwoerd, B. L. G. Bakker, V. A. Karmanov · 2 citations
Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ph #hep-th #nucl-th
paper · pdf · doi:10.1103/physrevc.58.3093
published as Phys.Rev.C58:3093-3108,1998 · 17 pages, revtex, 14 figures, submitted to Phys.Rev.C
arxiv created 1998/06/15 · openalex publication_date 1998/12/01 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We investigate in a model with scalar ``nucleons'' and mesons the contributions of higher Fock states that are neglected in the ladder approximation of the Lippmann-Schwinger equation. This leads to a breaking of covariance, both in light-front and in instant-form Hamiltonian dynamics. The lowest Fock sector neglected has two mesons in the intermediate state and corresponds to the stretched box. First we show in a simplified example that the contributions of higher Fock states are much smaller on the light-front than in instant-form dynamics. Then we show for a scattering amplitude above threshold that the stretched boxes are small, however necessary to retain covariance. For an off-energy-shell amplitude covariance is not necessarily maintained and this is confirmed by our calculations. Again, the stretched boxes are found to be small.