The tensor force in heavy nuclei: High momentum collectivity of unnatural parity excitations

Abstract

The possibility of collectivity at high momentum transfer in unnatural parity states in finite nuclei, is outlined. This phenomenon is produced by the strong tensor force in the one pion exchange interaction operating coherently in a large oscillator space. The collectivity is observed at momenta q ~ (2-3) m~ corresponding to the critical momentum of pion condensation. If existent, such collective behaviour is expected to be seen in differential cross sections, e.g. for proton inelastic scattering, leading to unnatural parity states.

High-lyingM 1-states of spherical nuclei

“…In [28] the calculations for 9~ have been performed, and the obtained results coincide qualitatively with those for z~ All the above mentioned conclusions have been obtained within the simple model using separable effective forces in the spin-isospin channel. Therefore it is legitimate to inquire whether the change of the results presented will be essential, if one uses more realistic effective forces, in particular, the tensor components of these forces and finite range forces [30]. There exists also the assumption [24] that the values of the effective gyromagnetic factors in heavy nuclei are strongly quenched (in 2~ geff 0.5gfsree).…”

Proximity to the Rho-Meson Condensation Threshold in Nuclei

“…In addition to these meson-exchange potentials, all remaining many-body correlations are introduced in terms of the phenomenological Landau-Migdal short-range interaction 1 g' whose q dependence is conveniently expressed as^'feO ^/ir 2^2 )/^* 2 ]^'* The tensor part h' is generally believed to be quite small compared to the leading tensor pieces from OPE and TPE at finite q and is dropped completely for our numerical study. 19 An isobar-hole interaction is also provided by making appropriate changes of operators a - § , 1 andr-T and of coupling constantsf^f^* and p + p* inEqs. (l)-(3).…”