  The spectrum of gluons in the presence of a static quark-antiquark pair is
studied using Monte Carlo simulations on anisotropic space-time lattices. For
very small quark-antiquark separations R, the level orderings and approximate
degeneracies disagree with the expectations from an effective string theory. As
the quark-antiquark separation R increases, a dramatic rearrangement of the
energies occurs, and above 2 fm, all of the levels studied show behavior
consistent with an effective string description. The energy spacings are nearly
pi/R, but a tantalizing fine structure remains. In addition to 4-dimensional
SU(3) gauge theory, results from 3-dimensional SU(2) and compact U(1) gauge
theories are also presented.
