The S Parameter in QCD from Domain Wall Fermions

Peter boyle, Luigi Del Debbio, Jan Wennekers, James zanotti

Research output: Contribution to journalArticlepeer-review


We have computed the SU(2) Low Energy Constant l5 and the mass splitting between charged and neutral pions from a lattice QCD simulation of nf = 2 + 1 flavors of Domain Wall Fermions at a scale of a-1 = 2.33GeV. Relating l5 to the S parameter in QCD we obtain a value of S(mH=120GeV) = 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.
Original languageEnglish
Pages (from-to)-
Number of pages8
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number1
Publication statusPublished - 14 Jan 2010


  • hep-lat


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