The photoproduction of positive pions from hydrogen at energies of 1.1 to 1.4 GEV

Kilner, Joseph R. ; Walker, Robert Lee ;
CIT-4, 1963.
Inspire Record 44252 DOI 10.17182/hepdata.37169

A magnetic spectrometer and counter telescope system was used to detect positive pions photoproduced singly in a liquid hydrogen target. Measurements of the differential cross section were made at mean laboratory photon energies, k = 1.1, 1.2, 1.3, and 1.4 GeV and in the angular range from 5° to 165 ° in the center-of-momentum system of the pion. The shape of the angular distribution of the differential cross sections at each value of k is very similar to that of the previously measured distribution at k = 1.0 GeV. The angular distributions were integrated to give the total cross sections. The third pion-nucleon "resonance" peak is seen to be very close to k = 1.0 GeV. A leveling off of the total cross section at k = 1.4 GeV may be due to the fourth "resonance". The accurate small angle data at k = 1.1 and 1.2 GeV permitted a reasonable extrapolation of the differential cross section to the pion-nucleon pole. The value of the pion-nucleon coupling constant, f, was extracted from this extrapolation. The result was f^2 = 0.078 ± 0.011.

4 data tables

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Photoproduction of pi+ Mesons at 3.4 and 5.0 BeV

Joseph, P.M. ; Hicks, N. ; Litt, L. ; et al.
Phys.Rev.Lett. 19 (1967) 1206-1209, 1967.
Inspire Record 52485 DOI 10.17182/hepdata.21755

We report measurements of the photoproduction from hydrogen of single π+ mesons at gamma-ray energies of 3.4 and 5.0 BeV and at laboratory angles of 5.1°, 7.1°, 9.9°, and 15.1°. The s dependence at fixed t is derived for momentum transfers of -0.20, -0.37, and -0.70 BeV2. The pion data are compared with a Reggeized one-pion-exchange model.

1 data table

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Gamma p INTERACTIONS AT 5.25-GeV

Ballam, Joseph ; Chadwick, G.B. ; Guiragossian, Zaven G.T. ; et al.
Phys.Lett.B 30 (1969) 421-425, 1969.
Inspire Record 54868 DOI 10.17182/hepdata.28894

Photoproduction of resonances has been studied using positron annihilation radiation at 5.25 GeV in the SLAC 40-inch hydrogen bubble chamber. Results are presented on the nonstrange particle events and related to the vector dominance model.

1 data table

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PRODUCTION OF B (1235) AND rho (1710) 4 pi ENHANCEMENTS IN 16-GeV/c pi+- p COLLISIONS

Ballam, Joseph ; Chadwick, G.B. ; Guiragossian, Zaven G.T. ; et al.
Phys.Rev.D 3 (1971) 2606, 1971.
Inspire Record 67113 DOI 10.17182/hepdata.23670

Production of B(1235) and ρ(1710) mesons is observed in the four-pion decay modes π+π+π−π0 in 16−GeVc π±p collisions. Decay distributions and branching fractions into various modes are presented. Absence of the two-pion mode π−π0 for the ρ(1710) is noted.

1 data table

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VAN HOVE ANALYSIS OF THE REACTIONS pi- p ---> pi- pi- pi+ p AND pi+ p ---> pi+ pi+ pi- p AT 16-GeV/c

Ballam, Joseph ; Chadwick, G.B. ; Guiragossian, Zaven G.T. ; et al.
Phys.Rev.D 4 (1971) 1946, 1971.
Inspire Record 67149 DOI 10.17182/hepdata.23179

Data from the reactions π−p→π−π−π+p and π+p→π+π+π−p have been obtained at 16 GeV/c in approximately equal samples from the BNL 80-in. hydrogen bubble chamber. We have studied both reactions for resonance production and compared our results with predictions of the one-pion-exchange model (OPEM) calculated by Wolf. The four-body longitudinal phase-space (LPS) plot suggested by Van Hove was used to analyze the data from both reactions. The events were separated according to distinct regions of the LPS plot in order to study the following classes of quasi-two-body final states: (1) diffractively produced three-pion states, (2) diffractively produced ππp states, (3) double-resonance production such as ρ0Δ++, (4) single-resonance production such as π−π−Δ++. The Van Hove analysis provided a much cleaner separation of resonances from background effects than the usual techniques. We observe production of the A1 and A2 mesons as well as the N*(1470) and N*(1700) isobars in the π+π−p system for both reactions. There is strong formation of the doubly resonant states ρ0Δ++ and f0Δ++ and the general features of the nondiffractive events are all in good agreement with one-pion exchange. Detailed comparisons between the data and the OPEM in each LPS plot region show that Van Hove analysis provides a sensitive test for the OPE model.

6 data tables

DEDUCED FROM PRONG CROSS SECTIONS NORMALIZED USING THE DATA OF K. J. FOLEY ET AL., PRL 19, 330 (1967).

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Bubble Chamber Study of Photoproduction by 2.8-GeV and 4.7-GeV Polarized Photons. 1. Cross-Section Determinations and Production of rho0 and Delta++ in the Reaction gamma p --> p pi+ pi-

Ballam, Joseph ; Chadwick, G.B. ; Gearhart, R. ; et al.
Phys.Rev.D 5 (1972) 545, 1972.
Inspire Record 67165 DOI 10.17182/hepdata.3635

Photoproduction is studied at 2.8 and 4.7 GeV using a linearly polarized monoenergetic photon beam in a hydrogen bubble chamber. We discuss the experimental procedure, the determination of channel cross sections, and the analysis of the channel γp→pπ+π−. A model-independent analysis of the ρ0-decay angular distribution allows us to measure nine independent density-matrix elements. From these we find that the reaction γp→pρ0 proceeds almost completely through natural parity exchange for squared momentum transfers |t|<1 GeV2 and that the ρ production mechanism is consistent with s-channel c.m. helicity conservation for |t|<0.4 GeV2. A cross section for the production of π+π− pairs in the s-channel c.m. helicity-conserving p-wave state is determined. The ρ mass shape is studied as a function of momentum transfer and is found to be inconsistent with a t-independent Ross-Stodolsky factor. Using a t-dependent parametrization of the ρ0 mass shape we derive a phenomenological ρ0 cross section. We compare our phenomenological ρ0 cross section with other experiments and find good agreement for 0.05<|t|<1 GeV2. We discuss the discrepancies in the various determinations of the forward differential cross section. We study models for ρ0 photoproduction and find that the Söding model best describes the data. Using the Söding model we determine a ρ0 cross section. We determine cross sections and nine density-matrix elements for γp→Δ++π−. The parity asymmetry for Δ++ production is incompatible with simple one-pion exchange. We compare Δ++ production with models.

20 data tables

FROM QUOTED TOPOLOGICAL CROSS SECTIONS. 1.44 GEV CROSS SECTION PUBLISHED PREVIOUSLY.

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NO TMIN CORRECTION HAS BEEN MADE.

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K+ p elastic scattering between 432 and 939 mev/c

Adams, C.J. ; Davies, J.D. ; Dowell, J.D. ; et al.
Phys.Rev.D 4 (1971) 2637-2641, 1971.
Inspire Record 74758 DOI 10.17182/hepdata.23177

We present data from a spark-chamber study of K+p elastic scattering between 432 and 939 MeV/c, over the range −0.6<cosθc.m.<+0.7. With measurements at 13 momenta, and between 2000 events at the lowest momentum and 5000 events at the highest momentum, there is a major improvement over previous data. The elastic cross sections deduced from the differential cross sections are almost independent of momentum through the range covered. The data are inconsistent with counter measurements of the total cross section which suggest a sharp shoulder in the cross section at about 700 MeV/c.

15 data tables

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Vector Meson Production by Polarized Photons at 2.8-GeV, 4.7-GeV, and 9.3-GeV

Ballam, Joseph ; Chadwick, G.B. ; Eisenberg, Y. ; et al.
Phys.Rev.D 7 (1973) 3150, 1973.
Inspire Record 73602 DOI 10.17182/hepdata.43496

We present results on vector-meson photoproduction via γp→Vp in the LBL-SLAC 82-in. hydrogen bubble chamber exposed to a linearly polarized photon beam at 2.8, 4.7, and 9.3 GeV. We find ρ0 production to have the characteristics of a diffractive process, i.e., a cross section decreasing slowly with energy and a differential cross section with slope of ∼ 6.5 GeV−2. Within errors the ρ0 production amplitudes are entirely due to natural-parity exchange. s-channel helicity is conserved to a high degree in the γ→ρ0 transition. We find evidence for small helicity-flip amplitudes for ππ pairs in the ρ0 region. Photoproduction of ω mesons is separated into its natural- (σN) and unnatural- (σU) parity-exchange contributions. The Eγ and t dependence and the spin density matrix of the unnatural-parity-exchange contribution are consistent with a one-pion-exchange process. The natural-parity-exchange part has characteristics similar to ρ0 production. At 9.3 GeV the ratio of σ(ρ0) to σN(ω) is ∼ 7. The slope of the φ differential cross section is ∼ 4.5 GeV−2, smaller than that of ρ0 and ω production. Natural-parity exchange is the main contributor to φ production. No evidence for higher-mass vector mesons is found in ππ, πππ, or KK¯ final states. The s and t dependences of Compton scattering as calculated from ρ, ω, and φ photoproduction using vector-meson dominance agree with experiment, but the predicted Compton cross section is too small by a factor of 2.

47 data tables

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TOTAL AND PARTIAL gamma p CROSS-SECTIONS AT 9.3-GeV

Bingham, H.H. ; Fretter, W.B. ; Podolsky, William J. ; et al.
Phys.Rev.D 8 (1973) 1277, 1973.
Inspire Record 81022 DOI 10.17182/hepdata.22092

We report γp total, topological, and channel cross sections at 9.3 GeV from a bubblechamber experiment using a nearly monoenergetic photon beam.

1 data table

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K+ p elastic scattering between 432 and 939 mev/c and phase shift analysis

Adams, C.J. ; Cox, G.F. ; Davies, J.D. ; et al.
Nucl.Phys.B 66 (1973) 36-77, 1973.
Inspire Record 94900 DOI 10.17182/hepdata.32390

Measurements of K + p elastic scattering have been carried out at 13 momenta between 432 MeV/ c and 939 MeV/ c using spark chambers. The data establish unambiguously the constructive interference of the Coulomb and nuclear amplitudes at 432 MeV/ c . The elastic cross section is found to be independent of momentum through the range covered. The phase shifts for S, P, D and F waves are obtained in an energy dependent analysis in which higher waves are held at theoretical values. The initial behaviour ofthe P, D and F amplitudes is quite close to that predicted by the calculation of the peripheral partial waves. Only the P3 and D5 amplitudes become strikingly different with increasing momentum.

14 data tables

COULOMB INTERFERENCE EFFECT SEEN AT SMALL ANGLES.

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