Improved π0,η,η′ transition form factors in resonancechiral theory and their aHLbL μ contribution

Abstract

Working with Resonance Chiral Theory, within the two resonance multiplets saturation scheme, we satisfy leading (and some subleading) chiral and asymptotic QCD constraints and accurately fit simultaneously the π0,η,η′transition form factors, for single and double virtuality. In the latter case, we supplement the few available measurements with lattice data to ensure a faithful description. Mainly due to the new results for the doubly virtual case, we improve over existing descriptions for the η and η′. Our evaluationof the corresponding pole contributions to the hadronic light-by-light piece of the muon g−2 read: aπ0-pole µ=(61.9 ±0.6+2.4−1.5)×10−11, aη-poleµ=(15.2 ±0.5+1.1−0.8)×10−11 and aη′-poleµ=(14.2 ±0.7+1.4−0.9)×10−11, for a total of aπ0+η+η′-poleµ= (91.3 ±1.0+3.0−1.9)×10−11, where the first and second errors are the statistical and systematic uncertainties, respectively.