Role of Gamow-Teller suppression andM1radiative widths onπ−photoproduction from

Proximity to the Rho-Meson Condensation Threshold in Nuclei

“…3 " 6 Recent discussions have thus focused on the possibility of observing precritical phenomena in ordinary nucleio 7 " 9 The proximity of the pion condensation threshold should amplify the pionic field in finite nuclei and thus increase the cross sections of (e,e'), 8 (p,p'), 9 ' 10 and (n,y) or (y,7i) reactions 11 ' 12 for isovector unnatural-parity transitions at large momentum transfer.…”

“…Quantitative discussions of precritical behavior have centered on the 1 + , T =1 state of 12 smaller than the data from (e ,e') reactions. 814 Analyses in the context of precritical behavior wither-andp-meson exchange interactions have led to values of the Landau-Migdal parameter g-'^0.4.…”

Measurement ofN14(γ, π+)Cottman1, Min2, Stoler3 et al. 1985Phys. Rev. Lett.23010View full textAdd to dashboardCite

“…We note that the quality of these data greatly exceeds that obtainable with earlier facilities. 1, 2 The measurement of 14 N(y, 7r + ) 14 C(g.s.) was motivated by the need for high-quality (y, TT + ) data which would be especially sensitive to photoproduction dynamics.…”

“…reaction, and thus the relative strength of the other terms increased. 2,4 Noteworthy features observed from comparison of distorted-wave impulse-approximation (DWIA) calculations to the data reported here are as follows: (1) The effects of the momentum-dependent terms in the pion-photoproduction operator, especially the pionpole term, are clearly observed for the first time; (2) the results are sensitive to the nuclear structure in a different manner than the analogous (e,e') formfactor data; and (3) DWIA momentum-space calculations are in excellent agreement with the experimental data provided that all aspects of the photoproduction operator are carefully treated.…”

“…Singham and Tabakin, 2 and Figureau and Mukhopadhyay, 4 have suggested that the KR term is suppressed because of the vanishingly small Gamow-Teller matrix element and thus the other terms play a more important role. 2 In particular, the studies of Toker and Tabakin imply that a proper treatment of the pion-pole term is necessary for any successful calculation of the 14 N(y, 7r + ) 14 C(g.s.) reaction.…”