Lees, J.P.
nucl-ex
Electron production
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Measurement of the target asymmetry of eta and pi0 photoproduction on the proton.

Bock, A. ; Anton, G. ; Beulertz, W. ; et al.
Phys.Rev.Lett. 81 (1998) 534-537, 1998.
Inspire Record 474492 DOI 10.17182/hepdata.19492

At the tagged photon facility PHOENICS at the Bonn accelerator ELSA a measurement of the target asymmetry of the reaction γp→pη from threshold to 1150 MeV has been performed. Simultaneously the reaction γp→pπ0 has been measured in the first resonance region. Results are presented for both reactions. The target asymmetry data are suited to put considerable constraints on the model parameters used for the theoretical description of meson photoproduction.

3 data tables
Table 1

The errors include statistical and systematic errors added in quadrature. The target asymmetry determines as the rates belonging to different polarization states: (N_pol-up-N_pol_down)/(N_pol-up+N_pol_down).

Table 2

The errors include statistical and systematic errors added in quadrature. The target asymmetry determines as the rates belonging to different polarization states: (N_pol-up-N_pol_down)/(N_pol-up+N_pol_down).

Table 3

The errors include statistical and systematic errors added in quadrature. The target asymmetry determines as the rates belonging to different polarization states: (N_pol-up-N_pol_down)/(N_pol-up+N_pol_down).


ELECTROPRODUCTION OF pi0 MESONS ON PROTONS AT W = 1400-MeV TO 2000-MeV, q**2 = 0.01-GeV**2 TO 0.1-GeV**2, AND t = 0.6-GeV**2 TO 2.2-GeV**2 CORRESPONDING TO Theta (CM) pi = 145-degrees TO 180-degrees

Blume, H. ; Farber, R. ; Feldmann, N. ; et al.
Z.Phys.C 16 (1983) 283, 1983.
Inspire Record 180101 DOI 10.17182/hepdata.16387

The electroproduction of π0-mesons on protons has been measured with electrons of 1.7 and 2.1 GeV energy in the region of the nucleon resonances at\(W = \sqrt {(q + p)^2 }= 1,400 - 2,000MeV\) at rather low values of |q2|=|(e−e′)2|=0.01–0.1 GeV2 but at high values of the nucleon recoil |t|=|(p−p′)2|≈0.6–2.2 GeV2 corresponding to\(\Theta _\pi ^{cm}\approx 145^ \circ- 180^ \circ\). Up toW≈1,650 MeV the cross section for π0-production with virtual photons of |q2|≈0.03 GeV2 is only slightly smaller than that with real photons. ForW≳1,700 MeV the cross section at |q2|≈0.03 GeV2 is on average a factor of 2 smaller than that atq2=0 but only slightly higher than that at |q2|≈0.3–1 GeV2.

6 data tables
Table 1

INCLUDING RADIATIVE CORRECTIONS.

Table 2

INCLUDING RADIATIVE CORRECTIONS.

Table 3

INCLUDING RADIATIVE CORRECTIONS.

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