Photoproduction of ϱ0 and ω in γd interactions at 4.3 GeV

Eisenberg, Y. ; Haber, B. ; Kogan, E. ; et al.
Nucl.Phys.B 42 (1972) 349-368, 1972.
Inspire Record 67692 DOI 10.17182/hepdata.69930

Coherent photoproduction of ϱ 0 and ω at E γ = 4.3 GeV is observed. The ratios ϱ 0 d/ ω d and ϱ 0 d/ ϱ 0 p are discussed and compared with theoretical predictions. By comparing our data with total photoabsorption cross sections we determine the direct vector meson-photon coupling to be γ ϱ 2 /4 π = 0.29 ± 0.06. With this value we find the VDM relations between photoproduction and Compton scattering well satisfied.

7 data tables

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Photoproduction of omega Mesons from Complex Nuclei Targets

Brodbeck, T.J. ; Coddington, P. ; Morris, J.V. ; et al.
Nucl.Phys.B 136 (1978) 95-114, 1978.
Inspire Record 122500 DOI 10.17182/hepdata.35124

Measurements are presented of the cross sections for omega meson photoproduction at a mean energy of 3.9 GeV from nuclear targets of D, Be, C, Al, Cu, Ag, Au. An optical and Glauber model analysis of the coherent cross sections has been performed to obtain the ω-nucleon cross section, σ ωN , and the photon-omega coupling constant γ ω 2 /4 π . Our results are summarised in table 4. We find good agreement with the quark model prediction that σ ω N = σ ϱ N , and with the value of γ ω 2 /4 π determined from the storage ring experiments and from an earlier complex nuclei measurement. However, we disagree with more recent complex nuclei measurements which found a high value of γ ω 2 /4 π .

2 data tables

COHERENT OMEGA PHOTOPRODUCTION AFTER SUBTRACTING A FITTED INCOHERENT SIGNAL.

COHERENT OMEGA PHOTOPRODUCTION AFTER SUBTRACTING A FITTED INCOHERENT SIGNAL.


Measurement of the gamma-V Coupling Constants and sigma-T (Vd) from Coherent gamma-d Interactions at 7.5-GeV

Alexander, G. ; Benary, O. ; Gandsman, J. ; et al.
Phys.Lett.B 57 (1975) 487-490, 1975.
Inspire Record 2480 DOI 10.17182/hepdata.27813

We have measured the total and differential cross-sections for coherently photoproduced ϱ, ω and ϱ′ on deuterium at 7.5 GeV. Using VDM relations, we have obtained γ ω 2 / γ ϱ 2 = 7.1 ± 1.5, σ T ( ϱ d) = (54 ± 2) mb and σ T ( ω d) = (56 ± 5) mb. Assuming the amplitude for ϱ′ production via an intermediate ϱ 0 to be small and that the amplitudes for ϱp and ϱ′p elastic scattering are comparable, we found γ ϱ ′ 2 / γ ϱ 2 = 6.0 ± 1.2 and σ T ( ϱ ′d) = (47 ± 6) mb.

2 data tables

No description provided.

FROM AN EXPONENTIAL FIT WITH DEUTERON FORM FACTOR.


Vector meson production by 4.3 GeV polarized photons on deuterium

Eisenberg, Y. ; Haber, B. ; Kogan, E. ; et al.
Nucl.Phys.B 104 (1976) 61-97, 1976.
Inspire Record 98707 DOI 10.17182/hepdata.35922

Cross sections for γd and γn interactions and photoproduction of ϱ 0 and ω are studied at 4.3 GeV, using a linearly polarized photon beam in a deuterium bubble chamber. We find that σ T (γ n ) ⋍ σ T (γ p ) within about 5% and that the γn average charge multiplicity is lower than γp by 0.42±0.09. About 4000 ϱ 0 events and 70 coherent ω events are observed. We present total and differential cross sections for both xoherent and incoherent ϱ 0 production on deuterium, as well as decay angular distributions and density-matrix elements. We find that the t -channel isospin-one exchange amplitude in γ N → ϱ 0 N (e.g. A 2 exchange) is at most 5–13% of the dominant isoscalar amplituds. The ϱ 0 production mechanism is dominantly s -channel helicity-conserving (SHC) on both neutrons and protons. We find that relative to the SHC amplitudes, the single and double helicity-flip amplitudes at the γϱ 0 vertex are of the order of 10–15% for | t | > 0.25 GeV 2 , and have the same sign on both nucleons. This shows that helicity-flip is mainly due to isoscalar exchanges. The ratio of ω to ϱ 0 coherent forward cross sections is found to be 0.16±0.04. The natural-parity exchange part of γ N → ω N is strongly dominated by isoscalar exchanges, and the magnitude of the isovector-exchange is consistent with zero.

5 data tables

TOPOLOGICAL CROSS SECTIONS AND AVERAGE CHARGE MULTIPLICITIES GIVEN IN TABLE 1.

'PARAMETRIZATION'.

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Omega Meson Photoproduction from Deuterium

Morris, J.V. ; Brodbeck, T.J. ; Coddington, P. ; et al.
Nucl.Phys.B 119 (1977) 420-434, 1977.
Inspire Record 109433 DOI 10.17182/hepdata.35515

Measurements are presented of the cross sections for ω meson photoproduction from deuterium at an average photon energy of 3.9 GeV. The cross section for the coherent process γ d → d ω is found to be 1.4 ± 0.5 μ b and that for the incoherent process γ d → np ω is 3.3 ± 0.7 μ b. The forward differential cross section for γ d → d ω is estimated to be (d σ /d t ) t =0 = 54 ± 20 μ b/GeV 2 . This result indicates that the value of the A 2 exchange amplitude in ω photoproduction from hydrogen is less than that predicted from the measurements of the difference between the total hadron photoproduction cross sections from neutrons and protons. We note that the world data tend to show that the A 2 exchange amplitude is more consistent with zero than with the value needed to explain these differences. Measurements are also presented of the ratio of the coupling constants of the photon to the ϱ and ω mesons which tend to favour the vector dominance model proposed by Das, Mathur and Okubo with exact SU(3) symmetry at infinite energies.

1 data table

AVERAGE OF TWO INDEPENDENT DATA SAMPLES AND ANALYSIS PROCEDURES.