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Photoproduction of $\pi^\circ$'S from protons in the forward direction in the region of the second and third resonances

Talman, Richard Michael ; Tollestrup, Alvin V. ;

CIT-8, 1963.

Inspire Record 44255 DOI 10.17182/hepdata.37170

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. The cross section for photoproduction of neutral pions from protons has been measured at energies near 750, 915 and 1150 Mev and over most of the forward-going [...] C.M. hemisphere. The experimental technique consisted of detecting both of the [...] decay photons with lead glass total absorption counters and, when convenient, the recoil proton with a single scintillation counter. The method is subject to rather large systematic errors but, within these, our results are consistent with other experiments wherever there are overlapping points. Our data has the striking feature that the cross section is very small at [...] in the region of the second and third pion nucleon resonances. Also, although the data is not inconsistent with a simple first, second and third resonance model, it appears likely that above the third resonance the pole process consisting of the exchange of a single vector meson is becoming important or even dominant. The evidence at this time mildly suggests that this behaviour is largely due to [...] mesons and under that hypothesis we are able to estimate some [...] meson coupling constants. For example, using a prescription of Gell-Mann and Zachariasen, we estimate the partial width for the decay [...] to be 240 Kev.

1 data table

Table 1

No description provided.

NEUTRAL PION PHOTOPRODUCTION AND PROTON COMPTON SCATTERING AT LARGE ANGLES

Shupe, M.A. ; Milburn, Richard H. ; Quinn, D.J. ; et al.

Phys.Rev.D 19 (1979) 1921-1930, 1979.

Inspire Record 145744 DOI 10.17182/hepdata.24315

The differential cross sections for γp→γp and γp→π0p have been measured for incident photon energies in the range of 2 to 6 GeV and for |t| ranging from 0.7 to 4.3 GeV2. This corresponds to a center-of-mass angle range of 45° to 128°. The energy dependence of the data is compared to that predicted by several parton models.

10 data tables

Table 1

No description provided.

Table 2

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Table 3

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Recoil-proton polarization in neutral-pion photoproduction between 1000 and 1800 mev

Tanaka, N. ; Castro, M.M. ; Milburn, Richard H. ; et al.

Phys.Rev.D 8 (1973) 1-8, 1973.

Inspire Record 81985 DOI 10.17182/hepdata.22112

Measurements are presented of the recoil-proton polarization for π0 photoproduction angles near 64° in the c.m. system. The steep angular dependence observed by others at lower energies persists to at least 1500 MeV, and the polarization crosses through zero near 63° over the entire 900-1600-MeV energy interval. Summary fits are made to available recoil-proton polarization data, 950-1250 MeV, and are found to require terms of order cos3θ, but no higher.

1 data table

Table 1

Axis error includes +- 0.0/0.0 contribution (?////).