How Many Degrees of Freedom Has the Gluon ?

Understand

In constituent models, glueballs are described as bound states of effective gluons.

• The dynamical mass generation lead to a gluon mass without violating gauge invariance.
• One can then consider three degrees of freedom for those effective massive gluons.
• However, models with only two degrees of freedom are shown to be in better agreement with the lattice glueball spectrum.