Neutral-Kaon Mixing From (2+1)-Flavor Domain-Wall Qcd

We present the first results for neutral-kaon mixing using (2+1)-flavors of domain-wall fermions. A new approach is used to extrapolate to the physical up and down quark masses from our numerical studies with pion masses in the range 240-420 MeV; only SU(2)(L)xSU(2)(R) chiral symmetry is assumed and the kaon is not assumed to be light. Our main result is B ($$$) over bar MSK(2 GeV)=0.524(10)(28) where the first error is statistical and the second incorporates estimates for all systematic errors.