Durant Sanjinés-Uriarte, Victoria (2019)
Chiral interactions for nuclear reactions and heavy nuclei.
Technische Universität Darmstadt
Dissertation, Erstveröffentlichung
Kurzbeschreibung (Abstract)
In this Thesis, we study nuclear reactions and interactions for heavy nuclei based on chiral effective field theory interactions. Thus, long-range nucleon interactions are described through pion exchanges, while the unresolved short-distance physics is encapsulated into low-energy constants that are typically fitted to few-body data. As a result of the systematic expansion of chiral effective field theory, the inclusion of many-body forces enters naturally at higher orders. At the same time, chiral effective field theory also enables order-by-order improvable calculations, as well as estimates of theoretical uncertainties.
The determination of nucleus-nucleus potentials is important not only to describe the nuclear reaction mechanism, but also to extract nuclear-structure information and for modeling nuclear reactions for astrophysics. We present the first determination of double-folding potentials based on chiral effective field theory at leading, next- to-leading, and next-to-next-to-leading order. To this end, we construct new soft local chiral effective field theory interactions. We benchmark this approach in the 16O–16O system, and present results for cross sections computed for elastic scattering up to 700 MeV in energy, as well as for the astrophysical S -factor of the fusion eaction. We also explore the impact of the density profile involved in the construction of the double-folding potentials. A first estimation of the impact of three-nucleon interactions as a triple-folding potential is presented as well.
For heavy nuclei, we focus on the calculation of three-nucleon interactions in their two-body normal-ordered form to be included in nuclear structure calculations. We develop a novel technique to perform the normal ordering directly in Jacobi basis, enabling the extension of the three-body model space in which these interactions can be included, as well as the storage of the matrix elements in all the steps of the calculation. To assess the validity of this new approach, we benchmark our matrix elements in JT-coupled basis against existing normal-ordered matrix elements using 4He and 16O as reference states in a harmonic oscillator basis. Additionally, we present first applications of these normal-ordered matrix elements in calculations of finite nuclei. Using the in-medium similarity renormalization group, we perform benchmarks for the 16 O ground-state energy and charge radius. We also test the convergence of our results with respect to the inclusion of high partial waves.
Moreover, we present results for sd-shell Hamiltonians constructed from chiral effective field theory operators using the machinery developed for the transformation of matrix elements. Finally, we discuss an approximation for harmonic oscillator radial wave functions, which could further optimize future calculations of normal-ordered matrix-elements for heavy nuclei.
Typ des Eintrags: | Dissertation | ||||
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Erschienen: | 2019 | ||||
Autor(en): | Durant Sanjinés-Uriarte, Victoria | ||||
Art des Eintrags: | Erstveröffentlichung | ||||
Titel: | Chiral interactions for nuclear reactions and heavy nuclei. | ||||
Sprache: | Englisch | ||||
Referenten: | Schwenk, Prof. Ph.D Achim ; Capel, Apl. Prof. Pierre | ||||
Publikationsjahr: | 15 Juli 2019 | ||||
Ort: | Darmstadt | ||||
Datum der mündlichen Prüfung: | 3 Dezember 2018 | ||||
URL / URN: | https://tuprints.ulb.tu-darmstadt.de/8519 | ||||
Kurzbeschreibung (Abstract): | In this Thesis, we study nuclear reactions and interactions for heavy nuclei based on chiral effective field theory interactions. Thus, long-range nucleon interactions are described through pion exchanges, while the unresolved short-distance physics is encapsulated into low-energy constants that are typically fitted to few-body data. As a result of the systematic expansion of chiral effective field theory, the inclusion of many-body forces enters naturally at higher orders. At the same time, chiral effective field theory also enables order-by-order improvable calculations, as well as estimates of theoretical uncertainties. The determination of nucleus-nucleus potentials is important not only to describe the nuclear reaction mechanism, but also to extract nuclear-structure information and for modeling nuclear reactions for astrophysics. We present the first determination of double-folding potentials based on chiral effective field theory at leading, next- to-leading, and next-to-next-to-leading order. To this end, we construct new soft local chiral effective field theory interactions. We benchmark this approach in the 16O–16O system, and present results for cross sections computed for elastic scattering up to 700 MeV in energy, as well as for the astrophysical S -factor of the fusion eaction. We also explore the impact of the density profile involved in the construction of the double-folding potentials. A first estimation of the impact of three-nucleon interactions as a triple-folding potential is presented as well. For heavy nuclei, we focus on the calculation of three-nucleon interactions in their two-body normal-ordered form to be included in nuclear structure calculations. We develop a novel technique to perform the normal ordering directly in Jacobi basis, enabling the extension of the three-body model space in which these interactions can be included, as well as the storage of the matrix elements in all the steps of the calculation. To assess the validity of this new approach, we benchmark our matrix elements in JT-coupled basis against existing normal-ordered matrix elements using 4He and 16O as reference states in a harmonic oscillator basis. Additionally, we present first applications of these normal-ordered matrix elements in calculations of finite nuclei. Using the in-medium similarity renormalization group, we perform benchmarks for the 16 O ground-state energy and charge radius. We also test the convergence of our results with respect to the inclusion of high partial waves. Moreover, we present results for sd-shell Hamiltonians constructed from chiral effective field theory operators using the machinery developed for the transformation of matrix elements. Finally, we discuss an approximation for harmonic oscillator radial wave functions, which could further optimize future calculations of normal-ordered matrix-elements for heavy nuclei. |
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URN: | urn:nbn:de:tuda-tuprints-85197 | ||||
Sachgruppe der Dewey Dezimalklassifikatin (DDC): | 500 Naturwissenschaften und Mathematik > 530 Physik | ||||
Fachbereich(e)/-gebiet(e): | 05 Fachbereich Physik 05 Fachbereich Physik > Institut für Kernphysik 05 Fachbereich Physik > Institut für Kernphysik > Theoretische Kernphysik |
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Hinterlegungsdatum: | 28 Jul 2019 19:55 | ||||
Letzte Änderung: | 28 Jul 2019 19:55 | ||||
PPN: | |||||
Referenten: | Schwenk, Prof. Ph.D Achim ; Capel, Apl. Prof. Pierre | ||||
Datum der mündlichen Prüfung / Verteidigung / mdl. Prüfung: | 3 Dezember 2018 | ||||
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