0000000000246702
AUTHOR
H. Tanabe
K+Λ photoproduction amplitudes incorporating absorptive effects and hypernuclear formation
Incorporating final-state absorptive effects, we have reexamined the γp→K+Λ elementary process to obtain amplitudes which are used for describing photoproduction of hypernuclei. Our model not only resolves the persisting trouble of the small KNΛ coupling constant, but also yields agreement with cross-section data at higher energies. Using our amplitudes, we calculate angular distributions for the reaction16O(γ, K+)Λ16N. While the forward cross-section increases with increasing energy, the total cross-section is found to remain almost constant fromEγ=1.2 GeV through 2 GeV, which suggests that rather low photon energies hold promise for exploration of hypernuclear excitations.
Absorptive effects inK+Λphotoproduction on nucleons and nuclei
Incorporating final state correlation effects, we have reinvestigated the ..gamma.. /sup 1/H..-->..K/sup +/..lambda.. elementary process. Our model not only resolves the persisting trouble of the small KN..lambda.. coupling constant, but also yields agreement with cross section data at higher energies. Using our amplitudes, we calculate angular distributions for the reaction /sup 16/O(..gamma..,K/sup +/)/sub ..lambda..//sup 16/N . While the forward cross section increases with increasing energy, the total cross section is almost constant from E/sub ..gamma../ = 1.2 GeV through 2 GeV, suggesting that rather low photon energies hold promise for exploration of hypernuclear excitations.
Coherent and incoherent η-photoproduction from nuclei
Abstract Elastic and inelastic η-photoproduction from complex nuclei is studied in a distorted-wave impulse approximation (DWIA) framework. The elementary operator is obtained by using a dynamical model which employs the reactions π N→ π N, π N→ ππ N and π − p→ η n to fix the hadronic vertex as well as the isobar propagators and the process γ N→ π N to constrain the electromagnetic vertex. The nuclear structure input for the inelastic transitions has been extracted from electron-scattering form factors. The η final-state interaction has been included via a simple optical potential using the ηN t -matrix as an input. We find that coherent η-production is dominated by the D 13 (1520) isobar w…
Pion-induced η production on nuclei
Abstract Low-energy η production on nuclei is investigated in a DWIA framework, using a Green function method. The η potential is constructed by folding medium-modified η N → S 11 → η N scattering amplitudes with nuclear wave functions. A phenomenological spreading potential is introduced for the intermediate S 11 resonance. Calculated ( π + , p ) η cross sections on 12 C and 16 O with the spreading potential having an imaginary part of the order of −50 ∼ −100 MeV compare favorably with recent experimental data. It is also shown that the energy dependence of the ( π + , η ) inclusive spectra is nicely reproduced, though the magnitude is somewhat underestimated.