Induced Isotensor Interactions in Heavy-Ion Double-Charge-Exchange Reactions and the Role of Initial and Final State Interactions
The role of initial state (ISI) and final state (FSI) ion–ion interactions in heavy-ion doublecharge-exchange (DCE) reactions A(Z, N) → A(Z ± 2, N ∓ 2) are studied for double single-chargeexchange (DSCE) reactions given by sequential actions of the isovector nucleon–nucleon (NN) T-matrix. In momentu...
| Autores: | , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2024 |
| País: | España |
| Institución: | Universidad de Sevilla (US) |
| Repositorio: | idUS. Depósito de Investigación de la Universidad de Sevilla |
| OAI Identifier: | oai:idus.us.es:11441/161287 |
| Acceso en línea: | https://hdl.handle.net/11441/161287 https://doi.org/10.3390/universe10020093 |
| Access Level: | acceso abierto |
| Palabra clave: | reaction theory nuclear many-body theory double-charge-exchange reactions double-beta decay induced interactions nuclear matrix elements |
| Sumario: | The role of initial state (ISI) and final state (FSI) ion–ion interactions in heavy-ion doublecharge-exchange (DCE) reactions A(Z, N) → A(Z ± 2, N ∓ 2) are studied for double single-chargeexchange (DSCE) reactions given by sequential actions of the isovector nucleon–nucleon (NN) T-matrix. In momentum representation, the second-order DSCE reaction amplitude is shown to be given in factorized form by projectile and target nuclear matrix elements and a reaction kernel containing ISI and FSI. Expanding the intermediate propagator in a Taylor series with respect to auxiliary energy allows us to perform the summation in the leading-order term over intermediate nuclear states in closure approximation. The nuclear matrix element attains a form given by the products of two-body interactions directly exciting the n 2 p −2 and p 2n −2 DCE transitions in the projectile and the target nucleus, respectively. A surprising result is that the intermediate propagation induces correlations between the transition vertices, showing that DSCE reactions are a two-nucleon process that resembles a system of interacting spin–isospin dipoles. Transformation of the DSCE NN T-matrix interactions from the reaction theoretical t-channel form to the s-channel operator structure required for spectroscopic purposes is elaborated in detail, showing that, in general, a rich spectrum of spin scalar, spin vector and higher-rank spin tensor multipole transitions will contribute to a DSCE reaction. Similarities (and differences) to two-neutrino double-beta decay (DBD) are discussed. ISI/FSI distortion and absorption effects are illustrated in black sphere approximation and in an illustrative application to data. |
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