Overlap fermions on a twisted mass sea
  We present first results of a mixed action project. We analyze gauge configurations generated with two flavors of dynamical twisted mass fermions. Neuberger's overlap Dirac operator is used for the valence sector. The various choices in the setup of the simulation are discussed. We employ chiral perturbation theory to describe the effects of using different actions in the sea and valence sector at non-zero lattice spacing. 
O. Bar, K. Jansen, S. Schaefer, L. Scorzato and A. Shindler