Casimir bag energy in the stochastic approximation to the pure QCD   vacuum
  We study the Casimir contribution to the bag energy coming from gluon field fluctuations, within the context of the stochastic vacuum model (SVM) of pure QCD. After formulating the problem in terms of the generating functional of field strength cumulants, we argue that the resulting predictions about the Casimir energy are compatible with the phenomenologically required bag energy term. 
C. D. Fosco and L. E. Oxman