Peculiarities in the Spectrum of the Adjoint Scalar Kinetic Operator in   Yang-Mills Theory
  We study the spectrum of low-lying eigenmodes of the kinetic operator for scalar particles, in the color adjoint representation of Yang-Mills theory. The kinetic operator is the covariant Laplacian, plus a constant which serves to renormalize mass. In the pure gauge theory, our data indicates that the interval between the lowest eigenvalue and the mobility edge tends to infinity in the continuum limit. On these grounds, it is suggested that the perturbative expression for the scalar propagator may be misleading even at distance scales that are small compared to the confinement scale. We also measure the density of low-lying eigenmodes, and find a possible connection to multi-critical matrix models of order m=1. 
J. Greensite, A.V. Kovalenko, S. Olejnik, M.I. Polikarpov, S.N.   Syritsyn, and V.I. Zakharov