ω photoproduction at the CBELSA/TAPS experiment

Wilson, A.; Cbelsa,

doi:10.1063/1.3701260

Cited by 12 publications

(26 citation statements)

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“…The SAPHIR [30], CLAS [32] and A2 [35] Collaborations' data sets are in fairly good agreement overall with each other in the overlapping energy regions but there are some noticeable discrepancies, especially, close to threshold energies, where the SAPHIR and CLAS data are poorer than the A2 data. The CBELSA/TAPS cross section data [33] show a clear discrepancy (which increases with energy and becomes clear for energies above W ∼ 2 GeV or so) with both the SAPHIR and CLAS data. The SAPHIR data seem systematically lower than both the CLAS and CBELSA/TAPS data for backward ω production angles.…”

Section: Numerical Results and Discussionmentioning

confidence: 81%

“…We now turn our attention to the analysis of the A2 [35] and CBELSA/TAPS [33] data to see how they influence the extracted resonance content compare to the CLAS data. Recall that there are some inconsistencies in the cross section of both the A2 and CBELSA/TAPS the CBELSA/TAPS data as explained above are shown in Fig.…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

“…The CLAS Collaboration provided another high-statistics measurements of the differential cross section and SDMEs [32]. Many data were reported in the year 2015 in particular: new measurements of differential cross sections and SDMEs and the first measurements of the double polarization asymmetries, the beam-target-helicity asymmetries E and G, were reported by the CBELSA/TAPS Collaboration [33,34]; a new measurement of the differential cross section with full production-angle coverage was reported by A2 Collaboration at MAMI [35]. Also, the beam asymmetry Σ has been measured by the GRAAL Collaboration [36].…”

Section: Introductionmentioning

confidence: 99%

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Nucleon resonances in γp→ωp reaction

et al. 2019

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The most recent high-precision data on spin observables Σ, T , P ′ , E, F and H reported by the CLAS Collaboration together with the previous data on differential cross sections and spin-densitymatrix elements reported by the CLAS, A2, GRAAL, SAPHIR and CBELSA/TAPS Collaborations for the reaction γp → ωp are analyzed within an effective Lagrangian approach. The reaction amplitude is constructed by considering the t-channel π and η exchanges, the s-channel nucleon and nucleon resonances exchanges, the u-channel nucleon exchange and the generalized contact current, with the last one being formulated to ensure that the full photoproduction amplitudes satisfy the generalized Ward-Takahashi identity and thus are fully gauge invariant. It is shown that all the available CLAS data can be satisfactorily described by considering the N (1520)3/2 − , N (1700)3/2 − , N (1720)3/2 + , N (1860)5/2 + , N (1875)3/2 − , N (1895)1/2 − and N (2060)5/2 − exchanges in the s channel. The parameters of these resonances are extracted and compared with those quoted by PDG.

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Section: Numerical Results and Discussionmentioning

confidence: 81%

Section: Numerical Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Nucleon resonances in γp→ωp reaction

et al. 2019

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“…Consequently, as shown in the present work, our rigorous theoretical analyses on the presently available highstatistics and wide-angle-coverage experimental data for the various physical observables will be valuable for a profound understanding for the light-flavor (ρ and ω) and hidden-flavor (J/ψ) vector meson photoproductions [64][65][66][67][68][69][70][71]. Related works will appear elsewhere.…”

Section: Discussionmentioning

confidence: 99%

Pomeron, nucleon-resonance, and (0+,0−,1+) -meson contributions in ϕ -meson photoproduction

Kim

Nam

2019

Phys. Rev. C

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We investigate the reaction mechanism of the φ-meson photoproduction off the proton target, i.e., γp → φp, up to √ s = 2.8 GeV. For this purpose, we employ an effective Lagrangian approach in the tree-level Born approximation, and we employ various experimental and theoretical inputs. As a theoretical setup, the vectorlike Pomeron (C = +1) is taken into account as a parameterized two-gluon exchange contribution. We also consider f1(1285) axial-vector-meson, (π, η) pseudoscalarmeson, and (a0, f0) scalar-meson exchanges in the t channel, in addition to the experimentally confirmed nucleon resonances, such as N * (2000, 5/2 + ) and N * (2300, 1/2 + ), for the direct φ-meson radiations in the s and u channels. We provide numerical results for the total and differential cross sections as well as the spin-density matrices in the Gottfried-Jackson, Adair, and helicity frames. We observe that, together with the universally accepted pomeron contribution, the considered meson and nucleon-resonance contributions play significant roles in reproducing the experimental data for the forward and backward φ-meson scattering-angle regions, respectively, indicating the nontrivial interferences between mesonic and baryonic contributions.

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“…This enables us to investigate meson exchanges of different parities independently, because they do not interfere with each other. More recently, experiments on ω photoproduction are extended to include the reaction at the deuteron target and the data on the reaction off a neutron target from the CBELSA/TAPS and GRAAL Collaborations [9,10] are available for photon energies up to 2 GeV. From the isospin symmetry, therefore, photoproduction of ω off the neutron target could provide further constraint on the different role of the π exchange in the isovector channel.…”

Section: Introductionmentioning

confidence: 99%

Features of ω photoproduction off nucleon target at forward angles: dominance of π exchange with Regge cuts and scaling of differential cross-sections

Choi²,

Kong³

2019

J. Phys. G: Nucl. Part. Phys.

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We investigate photoproduction of ω off a nucleon target γN → ωN by using a Reggeized model where π(135) + σ(500) + f1(1285) + f2(1270)+Pomeron exchanges are included in the t-channel for the reaction at forward angles. The reaction mechanism at low energy is featured by the dominance of the π exchange with the absorptive cuts introduced to modulate the pion contribution to both γp → ωp and γn → ωn reactions. Necessity of σ exchange is illustrated in the analysis of the cross section from natural parity exchanges. Cross sections for differential, total, and spin density matrix with parity and beam polarization asymmetries are reproduced and compared with existing data on γp → ωp. Scaled differential cross sections of Jefferson Lab data on γp → ωp are investigated at the production angle θ = 90 • with the nonlinear trajectories for a saturation. Differential and total cross sections for the γn → ωn reaction are analyzed to compare with recent experimental data at the CBELSA/TAPS Collaboration. An application to the γp → ω∆ + reaction is presented to demonstrate the significance of the π exchange in the total and differential cross sections. PACS numbers: 11.55.Jy, 13.40.-f, 13.60.Le for unnatural parity (P = −(−1) J ) exchanges.The Regge propagator is given bywritten in the collective form for the ϕ meson of spin-J which stands for all the mesons considered here. s 0 = 1 GeV 2 . The phase factor is, in general, taken to be of the canonical form, 1 2 [(−1) J + e −iπαJ (t) ], for each meson exchange. Photon and vector meson polarizations

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ω photoproduction at the CBELSA/TAPS experiment

Cited by 12 publications

References 0 publications

Nucleon resonances in γp→ωp reaction

Nucleon resonances in γp→ωp reaction

Pomeron, nucleon-resonance, and (0+,0−,1+) -meson contributions in ϕ -meson photoproduction

Features of ω photoproduction off nucleon target at forward angles: dominance of π exchange with Regge cuts and scaling of differential cross-sections

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