Single photoproduction of η-mesons of hydrogen in the forward direction at 4 and 6 GeV

Braunschweig, W.; Erlewein, W.; Frese, H.; Lübelsmeyer, K.; Meyer-Wachsmuth, H.; Schmitz, D.; Dratzig, A. Schultz von; Wessels, G.

doi:10.1016/0370-2693(70)90583-6

Cited by 37 publications

(60 citation statements)

References 11 publications

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“…The MCMC model, on the other hand, consists of an appropriate tool for the accurate determination of the Pauli blocking suppression factor. Equations (35) and (36) were derived using closure approximation without any specification about the photoproduction operator. The MCMC model also requires closure, since the NI amplitude for meson photoproduction from the nucleus is obtained as an incoherent sum of single nucleon amplitudes, but it is still possible to include the dynamical information for the elementary photoproduction during the evaluation of the Pauli-suppression factor.…”

Section: Pauli Blocking In the Mcmc Model: A Time-dependent Nonstomentioning

confidence: 99%

“…The first data points from DESY [34] taken at θ π 0 * = 0 are omitted in our fitting due to the effects of angular resolution neglected in our analysis. The data points are from DESY [35] (squares), SLAC [37] (triangles), and Cornell [38] (circles).…”

Section: Introductionmentioning

confidence: 99%

“…1 and 2, respectively; where a nice agreement between the Regge model and the data is achieved. The forward-angle data included in our analysis are from DESY [34,35], SLAC [36,37], and Cornell [38]. The constructive interference between the strong and Coulomb amplitudes is highly favorable for π 0 photoproduction (F 1 → F 1 + F C ), while for η photoproduction the situation is opposite (F 1 → F 1 − F C ).…”

Section: Introductionmentioning

confidence: 99%

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Nuclear incoherent photoproduction ofπ0andηfrom 4 to 12 GeV

Rodrigues¹,

Arruda‐Neto²,

Mesa³

et al. 2010

Phys. Rev. C

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The mechanism of incoherent π 0 and η photoproduction from complex nuclei is investigated from 4 to 12 GeV with an extended version of the multicollisional Monte Carlo (MCMC) intranuclear cascade model. The calculations take into account the elementary photoproduction amplitudes via a Regge model and the nuclear effects of photon shadowing, Pauli blocking, and meson-nucleus final-state interactions. The results for π 0 photoproduction reproduced for the first time the magnitude and energy dependence of the measured rations σ γ A /σ γ N for several nuclei (Be, C, Al, Cu, Ag, and Pb) from a Cornell experiment. The results for η photoproduction fitted the inelastic background in Cornell's yields remarkably well, which is clearly not isotropic as previously considered in Cornell's analysis. With this constraint for the background, the η → γ γ decay width was extracted using the Primakoff method, combining Be and Cu data [ η→γ γ = 0.476 (62)

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Section: Pauli Blocking In the Mcmc Model: A Time-dependent Nonstomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Nuclear incoherent photoproduction ofπ0andηfrom 4 to 12 GeV

Rodrigues¹,

Arruda‐Neto²,

Mesa³

et al. 2010

Phys. Rev. C

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show abstract

“…The gamma function Γ(α(t)) suppresses poles of the propagator in the butions only. The data at E lab γ = 4 GeV and 6 GeV are from DESY [18], at the lower energy we compare with the CLAS data [19] at E lab γ = 1.925 GeV.…”

Section: Maid and 450mentioning

confidence: 99%

Reggeized model forηandη′photoproduction

et al. 2003

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A reggeized model for η and η ′ photoproduction on the nucleon is presented. In this model, t-channel vector meson exchanges are described in terms of Regge trajectories to comply with the correct high energy behavior. We compare this reggeized model with an isobar model (η-MAID), where the t-channel exchanges are described by ρ and ω poles. Both models contain the same resonance contributions, and describe current γp → ηp data up to E lab γ = 2 GeV quite well, but only the reggeized model can be successfully extended to higher energies. For the γp → η ′ p reaction, the reggeized model is found to be able to give a satisfactory description. For the differential cross section data from SAPHIR, we find that the observed linear forward rise in cos θ near E lab γ = 1.6 GeV can be well described by the interference of an S 11 resonance and the Regge trajectory exchanges without any need for an additional P -wave resonance.

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“…[20,21], we may write the t-channel helicity amplitudes assuming !, , and b1 meson exchanges (VMD). Consequently, adding constructively the Coulomb contribution F C 1 , the natural parity exchange amplitudes (F 1 and F 3 ) and the b1 contribution (F 2 ) become: The shapes for the P and NC components of Eq.…”

mentioning

confidence: 99%

η→γγDecay Width via the Primakoff Cross Section

et al. 2008

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Incoherentphotoproduction in nuclei is evaluated at forward angles within 4 to 9 GeV using a multiple scattering Monte Carlo cascade calculation with full -nucleus final-state interactions. The Primakoff, nuclear coherent and nuclear incoherent components of the cross sections fit remarkably well previous measurements for Be and Cu from Cornell, suggesting a destructive interference between the Coulomb and nuclear coherent amplitudes for Cu. The inelastic background of the data is consistently attributed to the nuclear incoherent part, which is clearly not isotropic as previously considered in Cornell's analysis. A renewed interest in the Primakoff method appeared with the advent of the PrimEx Collaboration at the Jefferson Laboratory, which will provide a more precise measurement of ÿ 0 ! [9]. Furthermore, high precision and 0 photoproduction experiments are strongly encouraged by the forthcoming 12 GeV upgrade of the electron beam, demanding reliable methods for the accurate delineation of the nuclear background.The approaches developed so far for incoherent photoproduction from nuclei are restricted to 1 GeV, where the contribution from the S 11 1535 resonance largely dominates. The final-state interactions (FSI) of the mesons are taken into account either using optical potentials [10], the quantum molecular dynamics (QMD) model of Ref. [11], or the Boltzmann-Uehling-Uhlenbeck (BUU) transport model [12]. Obviously, these important theoretical developments are not suitable to describe incoherent production at higher energies.In this Letter, we present for the first time a consistent solution for the puzzling scenario of ÿ ! from Cornell using the multicollisional intranuclear cascade model MCMC [13][14][15] to describe the nuclear background. The Monte Carlo (MC) method takes into account incoherent photoproduction from nuclei at forward angles within 4 to 9 GeV, including -nucleus FSI via a multiple scattering framework.The forward angle photoproduction cross section is assumed to be in the form [16 -18] where T P , T NC , and T NI are the Primakoff (P), nuclear coherent (NC), and nuclear incoherent (NI) amplitudes, respectively, with ' representing the P-NC phase shift. The Coulomb amplitude is the sum of the amplitudes from the protons [6], such thatwhere 1=137, Z is the atomic number, k the photon energy, Q the four momentum transfer,F C k; the Coulomb form factor (FF) including -nucleus FSI; with ÿ ! , , , and representing the decay width, velocity, mass, and production angle of the meson, respectively. PRL 101, 012301 (2008)

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Single photoproduction of η-mesons of hydrogen in the forward direction at 4 and 6 GeV

Cited by 37 publications

References 11 publications

Nuclear incoherent photoproduction ofπ0andηfrom 4 to 12 GeV

Nuclear incoherent photoproduction ofπ0andηfrom 4 to 12 GeV

Reggeized model forηandη′photoproduction

η→γγDecay Width via the Primakoff Cross Section

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