Why people said (Witten, p. 11),
"For Yang-Mills theory. the mass gap is the reason that we do not see classical nonlinear Yang-Mills waves. They are a good approximation only under inaccessible conditions"
This post imported from StackExchange Physics at 2020-10-29 11:41 (UTC), posted by SE-user annie marie heart
Above the energy / mass gap, should we still see the classical nonlinear Yang-Mills waves?
In the spin system, for example, couldn't we still see the spin wave above the massive spin gap? Could it have linear dispersion or high order non-linear dispersion?