期刊
PHYSICAL REVIEW LETTERS
卷 121, 期 11, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevLett.121.112002
关键词
-
资金
- DFG [CRC 110]
- Bonn-Cologne Graduate School of Physics and Astronomy (BCGS)
- DOE [DE-FG02-00ER41132]
The pi(0) pole constitutes the lowest-lying singularity of the hadronic light-by-light (HLBL) tensor, and thus, it provides the leading contribution in a dispersive approach to HLBL scattering in the anomalous magnetic moment of the muon (g - 2)(mu). It is unambiguously defined in terms of the doubly virtual pion transition form factor, which in principle, can be accessed in its entirety by experiment. We demonstrate that, in the absence of a direct measurement, the full spacelike doubly virtual form factor can be reconstructed very accurately based on existing data for e(+)e(-) -> 3 pi, e(+)e(-)-> e(+)e(-)pi(0), and the pi(0) -> gamma gamma decay width. We derive a representation that incorporates all the low-lying singularities of the form factor, matches correctly onto the asymptotic behavior expected from perturbative QCD, and is suitable for the evaluation of the (g - 2)(mu) loop integral. The resulting value, a(mu)(pi 0-pole) = 62.6(-2.5)(+3.0) x 10(-11), for the first time, represents a complete data-driven determination of the pion-pole contribution with fully controlled uncertainty estimates. In particular, we show that already improved singly virtual measurements alone would allow one to further reduce the uncertainty in a(mu)(pi 0-pole).
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