Preliminary study of the I = 1 K [bar.K] scattering length from lattice QCD

The s-wave kaon-antikaon (K [bar.K]) scattering length is studied by lattice QCD using pion masses [m.sub.π] = 330-466 MeV. Through wall sources without gauge fixing, we calculate K [bar.K] four-point functions in the I = 1 channel with the "Asqtad"-improved staggered fermion formulation, and observe an attractive signal, which is consistent with pioneering lattice studies on K [bar.K] potential. Extrapolating the K [bar.K] scattering length to the physical point, we obtain [m.sub.K] [a.sup.l=1.sub.K [bar.K]] = 0.211 (33)(9), where the first error is statistical and the second is systematic. These simulations are conducted with MILC gauge configurations at lattice spacing a ≅ 0.15 fm.