mu+md from isovector pseudoscalar sum rules

AbstractWe revisit the isovector pseudoscalar sum rule determination of mu+md, using families of finite energy sum rules known to be very accurately satisfied in the isovector vector channel. The sum rule constraints are sufficiently strong to allow a determination of both mu+md and the excited resonance decay constants. The corresponding Borel transformed sum rules are also very well satisfied, providing a non-trivial consistency check on the treatment of direct instanton contributions. We obtain [mu+md](2 GeV)=7.8±1.1 MeV (in the MS scheme), only marginally compatible with the most recent sum rule determinations, but in good agreement with recent unquenched lattice extractions