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Analyzing powers for the pi- p(pol.) --> pi0 n reaction across the Delta(1232) resonance.

Gaulard, C.V. ; Riedel, C.M. ; Comfort, Joseph R. ; et al.

Phys.Rev.C 60 (1999) 024604, 1999.

Inspire Record 483795 DOI 10.17182/hepdata.51678

High quality analyzing powers for the π−p→→π0n reaction have been obtained with a polarized proton target over a broad angular range at incident kinetic energies of 98.1, 138.8, 165.9, and 214.4 MeV. This experiment nearly doubled the existing πN single-charge-exchange database for energies ranging from 10 to 230 MeV, with 36 new analyzing powers. The Neutral Meson Spectrometer was used to detect the outgoing neutral pions. The data are well described by recent phase-shift analyses. When combined with high-precision and accurate cross section data at the same energies, the data can provide a good test of the degree of isospin breaking in the region of the Δ(1232) resonance. They will also be helpful for constraining the evaluation of the pion-nucleon σ term from the scattering amplitudes.

4 data tables

Table 1

First error is total uncertainty.

Table 2

First error is total uncertainty.

Table 3

First error is total uncertainty.

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Measurement of the slope of the pi0 electromagnetic form-factor

Farzanpay, F. ; Gumplinger, P. ; Stetz, A. ; et al.

Phys.Lett.B 278 (1992) 413-418, 1992.

Inspire Record 338523 DOI 10.17182/hepdata.29240

We have measured the slope parameter of the π 0 electromagnetic form factor by measuring the partial branching ratio of the Dalitz decay π 0 → γe + e − into high-invariant-mass electron-positron pairs. We obtain a value a =0.026 with a total (statistical and systematic) error of ±0.054, in agreement with vector dominance and quark loop calculations.

1 data table

Table 1

The PI0 form factor is parameterized as F(M(ee)**2) = 1 + SLOPE*(M(ee)/M(pi))**2. Two metod are used (see text for detail).