Photoproduction of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>A</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>Meson in the Reaction<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>γ</mml:mi><mml:mi>p</mml:mi><mml:mo>→</mml:mo><mml:mi>n</mml:mi><mml:mrow><mml:msup><mml:mrow><mml:mi>π</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mr

Eisenberg, Y.; Haber, B.; Horovitz, Baruch; Peleg, Edna; Ronat, E.; Shapira, A.; Vishinsky, G.; Yekutieli, G.; Ballam, J.; Chadwick, G. B.; Guiragossián, Z.G.T.; Levy, A.; Menke, M.; Seyboth, P.; Wolf, G.

doi:10.1103/physrevlett.23.1322

Cited by 41 publications

(27 citation statements)

References 9 publications

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“…These values are quite consistent with the parameters given for the a,( 1320) in the Particle Data Group (PDG) tables 171.The only other measurement of a photoproduction was presented by Eisenberg et al[8] nearly 25 years ago. Those authors segregated their data into two parts, at 4.3 and 5.25 GeV, and they presented their cross sections for T + T + T -decays only.…”

supporting

confidence: 82%

Further results from charge-exchange photoproduction

Condo¹,

Handler²,

Bugg³

et al. 1993

Phys. Rev. D

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It is shown that the energy dependence of charge-exchange a: photoproduction (yp-nu:) agrees with a one-pion exchange mechanism. No evidence for the photoproduction of the a T(1260) is observed. If the dynamics of a , and a, photoproduction are assumed to be the same, the absence of evidence for the a , is shown to be consistent with either an extremely large a , hadronic width or with an a of mass somewhat less than 1260 MeV.PACS number(s): 13.60. Le, 12.40.Gg, 14.40.C~ Since the earliest photoproduction experiments, it has been known that the dominant reaction is the diffractive photoproduction of vector mesons. Arguments based on the vector meson dominance model have often been used to exclude anything but a minor amount of particle exchange as a mechanism for photoproduction [I]. Perhaps the most dramatic evidence of this is the unnatural parity-exchange contribution to w photoproduction [2]( yp -+wp ) where the cross section falls from 1 . 3 i 0 . 3 p b at 4.7 GeV to 0.1 i 0 . 2 p b at 9.3 GeV. Since the radiative width of the w is large [r(w-n-Oy )=850+50 keV], such a drop in the unnatural parity-exchange w production cross section leads to the conclusion that one-pion exchange (OPE) rapidly becomes an ineffectual production mechanism as E , increases. Complications in this interpretation do arisk, however. Some years ago the reaction Y P --+ -A + + was observed to persist to rather large energies. At 19.5 GeV this reaction was clearly evident with a production cross section [3] of 0.224i0.045 pb. While it was natural to assume that the reaction was mediated by OPE [r(p--+n--y ) = 7 1 f 12 keV], the decay angular distributions, the t' dependence of the production cross section, and its E y dependence all indicated difficulties in the interpretation of the reaction as evidence for OPE. Similar data and arguments had been noted previously at lower energies [4].Recently, in a study of the reaction [5] yp-+a2-A++-+n-+n--n--n-+p at 19.5 GeV; it was observed that the decay angular distributions of the A + + and a 2 as well as the t' distribution showed good agreement with OPE. Since this was the initial quantitative report of a , A t + associated photoproduction at any energy, we could obviously not study its E y dependence. The purpose of this paper is to present our evidence for a $ photoproduction from the reaction yp -nn-+rin--, which we will compare with lower-energy data. We shall also comment on the significance of this result as regards to the photoproduction of the a ,( 1260).Our data derive from a high-statistics hydrogen bubble chamber experiment which was performed at the Stanford Linear Accelerator Center with the primary purpose of studying open charm photoproduction. The experimental details regarding the data-taking phase of the experiment may be gleaned from prior publications [6].The photon beam, produced by backscattering laser light from SLAC 30-GeV electron beam had an average energy of 19.3 GeV with a full width at half maximum of 1.7GeV. The event sample for the nn-+n-+n--final state was...

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supporting

confidence: 82%

Further results from charge-exchange photoproduction

Condo¹,

Handler²,

Bugg³

et al. 1993

Phys. Rev. D

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“…where Θ and ϕ are polar and azimutal angles of π (or η) in this frame. Now using relations (10), the relations…”

Section: Cross Section Expansion Over Helicity States Of the πη Systemmentioning

confidence: 99%

On the possibilities to study the exotic state 1−+ in photoproduction of the πη, πη′ systems

Aznauryan

1995

Z. Phys. C - Particles and Fields

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We show that in photoproduction experiments there are propitious conditions to study the exotic state 1 −+ in the πη and πη ′ channels. We show that for unpolarized photon beam the contributions with natural and unnatural parity exchanges do not interfere with each other, the fact which gives additional arguments in the estimation of the correctness of phase shift analysis. In the reaction of photoproduction of π + η system in the mass range of a 2 (1320) more strong limit on the upper bound of the product Γ(1 −+ → πγ) × Br(1 −+ → πη) can be obtained than in experiments on Primakoff production on nuclei. In the photoproduction of π 0 η and π 0 η ′ systems there are propitious conditions to study the state 1 −+ in the coherent photoproduction on nuclei, the fact which will allow to enlarge significantly the statistics and makes the phase shift analysis more simple.

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“…We note here that the tensor meson photoproduction mechanisms depend very much on the charge of the produced tensor mesons. In particular, the one-pion exchange is known [193][194][195][196] to be the dominant mechanism for charged tensor meson production, while it is not allowed in neutral tensor meson production because of C parity. Thus the claim made by Dzierba et al [152] concerning the peak at W ∼ 1540 MeV generated by neutral tensor meson production must be re-examined.…”

Section: (I)mentioning

confidence: 99%

Pentaquark Θ+(1540) production in γN→KK¯N reactions

Nakayama

Lee

2006

Physics Reports

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The recent developments in the search of exotic pentaquark hadrons are briefly reviewed. We then focus on investigating how the exotic pentaquark Θ(1540) baryon production can be identified in the γN → KKN reactions, focusing on the influence of the background (non-Θ production) mechanisms. By imposing the SU(3) symmetry and using various quark model predictions, we are able to fix the coupling constants for evaluating the kaon backgrounds, the KK production through the intermediate vector meson and tensor meson photoproduction, and the mechanisms involving intermediate Λ (1116), Λ(1405), Λ(1520), Σ(1193), Σ(1385), and ∆(1232) states. The vector meson photoproduction part is calculated from a phenomenological model which describes well the experimental data at low energies. We point out that the neutral tensor meson production can not be due to π 0 -exchange as done by Dzierba et al. [Phys. Rev. D 69, 051901 (2004)] because of C parity. The neutral tensor meson production is estimated by considering the vector meson exchange and found to be too weak to generate any peak at the position near Θ(1540). For Θ(1540) production, we assume that it is an isoscalar and hence can only be produced in γn → K + K − n and γp → K 0 K 0 p reactions, but not in γp → K + K − p and γn → K 0 K 0 n. The total cross section data of γp → K + K − p is thus used to fix the form factors which regularize the background amplitudes so that the signal of Θ(1540) in γn → K + K − n and γp → K 0 K 0 p cross sections can be predicted.We find that the predicted K + K − and K + n invariant mass distributions of the γn → K + K − n reaction can qualitatively reproduce the shapes of the JLab data. However, the predicted Θ(1540) peak can not be identified unambiguously with the data. High statistics experiments are needed to resolve the problem. We also find that an even-parity Θ is more likely to be detected, while it will be difficult to identify an odd-parity Θ, even if it exists, from the background continuum, if its coupling constants are small as in the present quark model predictions.

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Photoproduction of theA2Meson in the Reactionγp→nπ+

Abstract: We observe production of the Ag meson in the reaction yp-^mr^TT^ir" at 4.3 and 5.25 GeV. The data are consistent with a one™pion-exchange production mechanism and we give an estimate of r(A2-* YTT) -0.5 MeV, A similar value for r(A2-*y7r) is also obtained using a vector dominance modeL

Cited by 41 publications

References 9 publications

Further results from charge-exchange photoproduction

Further results from charge-exchange photoproduction

On the possibilities to study the exotic state 1−+ in photoproduction of the πη, πη′ systems

Pentaquark Θ+(1540) production in γN→KK¯N reactions

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