A Lattice Study of the Glue in the Nucleon
  By introducing an additional operator into the action and using the Feynman-Hellmann theorem we describe a method to determine both the quark line connected and disconnected terms of matrix elements. As an illustration of the method we calculate the gluon contribution (chromo-electric and chromo-magnetic components) to the nucleon mass. 
R. Horsley, R. Millo, Y. Nakamura, H. Perlt, D. Pleiter, P. E. L.   Rakow, G. Schierholz, A. Schiller, F. Winter and J. M. Z...
hep-lat hep-ph nucl-th