Source: wikibot/on-shell-and-off-shell
= On shell and off shell
{wiki=On_shell_and_off_shell}
The terms "on-shell" and "off-shell" primarily arise in the context of quantum field theory and theoretical physics, specifically in the analysis of particles and their interactions. \#\#\# On-Shell - **Definition**: A state or a particle is said to be "on-shell" if it satisfies the physical equations of motion, typically the energy-momentum relation derived from the theory.