The $\Delta_{mix}$ parameter in the overlap on domain-wall mixed action
  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: $24^3 \times 64$ ($a m_l= 0.005$, $a=0.114\fm$) and $32^3 \times 64$ ($a m_l = 0.004, 0.006, 0.008$, $a=0.085\fm$). For pion masses close to $300\MeV$ we find \hbox{$\Delta_{mix}=0.030(6)\GeV^4$} at $a=0.114\fm$ and $\Delta_{mix}=0.033(12)\GeV^4$ 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 $\Delta_{mix}=0.030(6)(5)\GeV^4$, where the first error is statistical and the second is the systematic error associated with the fitting method. 
M. Lujan, A. Alexandru, T. Draper, W. Freeman, M. Gong, F.X. Lee, A.   Li, K.F. Liu, N. Mathur
hep-lat