Lujan, M (reprint author), George Washington Univ, Dept Phys, Washington, DC 20052 USA.
A direct calculation of the mixed action parameter Delta(mix) with valence overlap fermions on a domain-wall fermion sea is presented. The calculation is performed on four ensembles of the 2 + 1 flavor domain-wall gauge configurations: 24(3) x 64 (am(l) = 0.005, a = 0.114 fm) and 32(3) x 64 (am(l) = 0.004, 0.006, 0.008, a = 0.085 fm). For pion masses close to 300 MeV we find Delta(mix) = 0.030(6) GeV4 at a = 0.114 fm and Delta(mix) = 0.033(12) GeV4 at a = 0.085 fm. The results are quite independent of the lattice spacing and they are significantly smaller than the results for valence domain- wall fermions on asqtad sea or those of valence overlap fermions on clover sea. Combining the results extracted from these two ensembles, we get Delta(mix) = 0.030(6)(5) GeV4, where the first error is statistical and the second is the systematic error associated with the fitting method.