Observation of S11(1535) resonance in nuclear medium via the 12C(γ,η) reaction

Yorita, T.; Yamazaki, H.; Kinoshita, Toyohiko; Okuda, Takashi; Matsui, H.; Kasagi, J.; Suda, T.; Itoh, K.; Miyakawa, Takuma; Okuno, H.; Shimizu, H.; Yoshida, Hiroshi; Kinashi, T.; Maruyama, Tomoyuki

doi:10.1016/s0370-2693(00)00176-3

Cited by 44 publications

(57 citation statements)

References 25 publications

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“…Thereby one has access to the energies corresponding to eta mesons bound in nuclei. This is one of the differences from the eta production reactions on nuclear targets, where the eta-meson emitted from the nucleus is observed [28][29][30].…”

Section: Introductionmentioning

confidence: 88%

“…(24) and replacing the product of the hole wave-functions, ψ † j p (r)ψ j p (r) by the density distribution ρ(r) after the summation of the final states, we obtain an approximate response function S(E) ∝ dr r 2 ρ(r) G η E; ρ(r) . (28) This is the density weighted in-medium Green function introduced in (15) except for the normalization. According to the above argument, the approximate spectral function is close to the in-nucleus spectral function obtained by solving the Klein-Gordon equation, if the local density approximation is good enough.…”

Section: Formation Spectra Of η Mesonic Nucleimentioning

confidence: 99%

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Level crossing of particle–hole and mesonic modes in eta-mesonic nuclei

2008

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We study eta-meson properties in the infinite nuclear matter and in atomic nuclei with an emphasis on effects of the eta coupling to N * (1535)-nucleon-hole modes. The N * (1535) resonance, which dominates the low-energy eta-nucleon scattering, can be seen as a chiral partner of the nucleon. The change of the chiral mass gap between the N * and the nucleon in a nuclear medium has an impact on the properties of the eta-nucleus system. If the N * -nucleon mass gap decreases with a density increase (chiral symmetry restoration) the calculations show the existence of the resonance state at the energy about 60 MeV and two bound eta-nucleus states with the binding energies about −80 MeV. These states can have strong effect on predicted cross sections of the 12 C(γ , p) 11 B reaction with eta-meson production.

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Section: Introductionmentioning

confidence: 88%

Section: Formation Spectra Of η Mesonic Nucleimentioning

confidence: 99%

Level crossing of particle–hole and mesonic modes in eta-mesonic nuclei

2008

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“…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.…”

Section: Incoherentmentioning

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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“…The meson-nucleus FSI have been taken into account using optical potentials [7], classical propagation between meson-nucleon collisions [8], the quantum molecular dynamics (QMD) model of Ref. [9], or the BoltzmannUehling-Uhlenbeck (BUU) transport model [10]. All of these theoretical contributions have specific features not discussed in this article and represent important developments for the investigation of meson photoproduction within the nucleon resonances.…”

Section: Introductionmentioning

confidence: 99%

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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Observation of S11(1535) resonance in nuclear medium via the 12C(γ,η) reaction

Cited by 44 publications

References 25 publications

Level crossing of particle–hole and mesonic modes in eta-mesonic nuclei

Level crossing of particle–hole and mesonic modes in eta-mesonic nuclei

η→γγDecay Width via the Primakoff Cross Section

Nuclear incoherent photoproduction ofπ0andηfrom 4 to 12 GeV

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