S parameter in QCD from domain wall fermions

We have computed the SU(2) low- energy constant l(5) and the mass splitting between charged and neutral pions from a lattice QCD simulation of n(f) = 2 + 1 flavors of domain wall fermions at a scale of a(-1) = 2.33 GeV. Relating l(5) to the S parameter in QCD we obtain a value of S(m(H) = 120 GeV) = 0.42(7), in agreement with previous determinations. Our result can be compared with the value of S from electroweak precision data which constrains strongly interacting models of new physics like technicolor. This work in QCD serves as a test for the methods to compute the S parameter with domain wall fermions in theories beyond the standard model. We also infer a value for the pion mass splitting in agreement with experiment.