Three-pion contribution to hadronic vacuum polarization
Jul 2, 2019
24 pages
Published in:
- JHEP 08 (2019) 137
- Published: Aug 26, 2019
e-Print:
- 1907.01556 [hep-ph]
DOI:
- 10.1007/JHEP08(2019)137 (publication)
PDG: MASS
Report number:
- INT-PUB-19-030
View in:
Citations per year
Abstract: (Springer)
We address the contribution of the 3π channel to hadronic vacuum polarization (HVP) using a dispersive representation of the ee → 3π amplitude. This channel gives the second-largest individual contribution to the total HVP integral in the anomalous magnetic moment of the muon (g − 2), both to its absolute value and uncertainty. It is largely dominated by the narrow resonances ω and ϕ, but not to the extent that the off-peak regions were negligible, so that at the level of accuracy relevant for (g − 2) an analysis of the available data as model independent as possible becomes critical. Here, we provide such an analysis based on a global fit function using analyticity and unitarity of the underlying γ → 3π amplitude and its normalization from a chiral low-energy theorem, which, in particular, allows us to check the internal consistency of the various ee → 3π data sets. Overall, we obtain | = 46.2(6)(6) × 10 as our best estimate for the total 3π contribution consistent with all (low-energy) constraints from QCD. In combination with a recent dispersive analysis imposing the same constraints on the 2π channel below 1 GeV, this covers nearly 80% of the total HVP contribution, leading to = 692.3(3.3) × 10 when the remainder is taken from the literature, and thus reaffirming the (g−2) anomaly at the level of at least 3.4σ. As side products, we find for the vacuum-polarization-subtracted masses M = 782.63(3)(1) MeV and M = 1019.20(2)(1) MeV, confirming the tension to the ω mass as extracted from the 2π channel.Note:
- 24 pages, 1 figure; Appendix B added; version published in JHEP
- Chiral Lagrangians
- Effective Field Theories
- Nonperturbative Effects
- Precision QED
- vacuum polarization: hadronic
- muon: magnetic moment
- dispersion relation
- quantum chromodynamics
- analytic properties
- low-energy theorem
References(103)
Figures(3)