http://cds.cern.ch/record/147992/files/198312192.pdf

Chiral perturbation theory to one loop

http://www-com.physik.hu-berlin.de/~fjeger/gm2review.pdf

The muon g ― 2

We reevaluate the hadronic contributions to the muon magnetic anomaly, and to the running of the electromagnetic coupling constant at the Z-boson mass. We include new π
 +
 π
 − cross-section data from KLOE, all available multi-hadron data from BABAR, a reestimation of missing low-energy contributions using results on cross sections and process dynamics from BABAR, a reevaluation of all experimental contributions using the software package HVPTools together with a reanalysis of inter-experiment and inter-channel correlations, and a reevaluation of the continuum contributions from perturbative QCD at four loops. These improvements lead to a decrease in the hadronic contributions with respect to earlier evaluations. For the muon g−2 we find lowest-order hadronic contributions of (692.3±4.2)⋅10−10 and (701.5±4.7)⋅10−10 for the e
 +
 e
 −-based and τ-based analyses, respectively, and full Standard Model predictions that differ by 3.6σ and 2.4σ from the experimental value. For the e
 +
 e
 −-based five-quark hadronic contribution to $\alpha(M_{Z}^{2})$
 we find $\varDelta \alpha_{\mathrm{had}}^{(5)}(M_{Z}^{2}) =(274.9\pm1.0)\cdot10^{-4}$
 . The reduced electromagnetic coupling strength at M
 Z
 leads to an increase by 12 GeV in the central value of the Higgs boson mass obtained by the standard Gfitter fit to electroweak precision data.

/pdf/reevaluation-of-the-hadronic-contributions-to-the-muon-g-2-fgzoss2gup.pdf

Reevaluation of the hadronic contributions to the muon g−2 and to \alpha (M^{2}_{Z})

https://cds.cern.ch/record/166465/files/198604332.pdf

A measurement of the space-like pion electromagnetic form factor

Branching ratios and spectral functions of tau decays: Final ALEPH measurements and physics implications

Pion form factor from 480 MeV to 1100 MeV

Study of electron-positron annihilation into π+π− on the ϱo resonance

Comparison of Orsay results on vector mesons with the vector meson dominance model predictions

π+-π− production in e+e− collisions and ρ-ω interference

The differential cross section for the reaction $\ensuremath{\gamma}+p\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}n$ was measured at 19 photon energies between 300 and 750 MeV in the laboratory frame, for pion angles between 0\ifmmode^\circ\else\textdegree\fi{} and 130\ifmmode^\circ\else\textdegree\fi{} in the c.m. system. The pions were analyzed in angle and momentum with a magnetic spectrometer and detected by a counter telescope. The 0\ifmmode^\circ\else\textdegree\fi{} measurements could be achieved, in spite of the excessive positron rate, owing to a mass-spectrometer arrangement. No direct indication for the electromagnetic excitation of the ${P}_{11}$ resonance (1466 MeV) was found. Comparison is made with theoretical calculations of ${\ensuremath{\pi}}^{+}$ photoproduction.

J. Perez-Y-Jorba

Papers

Pion form factor from 480 MeV to 1100 MeV

Study of electron-positron annihilation into π+π− on the ϱo resonance

Comparison of Orsay results on vector mesons with the vector meson dominance model predictions

π+-π− production in e+e− collisions and ρ-ω interference

Positive Pion Photoproduction from Hydrogen for Incident Photon Energies 300-750 MeV