## Arts & Sciences Electronic Theses and Dissertations

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Summer 8-15-2016

#### Author's School

Graduate School of Arts and Sciences

Physics

#### Degree Name

Doctor of Philosophy (PhD)

Dissertation

#### Abstract

Pairing in asymmetric nuclear matter has been studied incorporating the effect of finite total momentum. We employ the generalized Cooper eigenvalue equation, which can be used to demonstrate the pairing instability and also generates reasonable pairing gaps compared to the traditional Bardeen-Cooper-Schrieffer (BCS) gap equation. From phase space arguments and the resulting strength of the pairing gap, we learn that the Larkin-Ovchinnikov-Fulde-Ferrell phase with a finite total momentum is favored over the conventional phase in asymmetric nuclear matter, but not in symmetric nuclear matter. To address open questions in neutron star cooling, neutron matter pairing gaps of the $^1S_0$ and the $^3P_2-^3F_2$ channels in a wide range of densities have been calculated using three different realistic interactions. Instead of the mean-field BCS procedure, we incorporate the influence of short- and long-range correlations in calculating the pairing gaps. Short-range correlations are treated to include the fragmentation of single-particle states, suppressing the gaps substantially. Long-range correlations dress the pairing interaction via density and spin modes, and provide a smaller correction. The results provide input for neutron-star cooling scenarios and are parametrized in a user friendly way. The results are of particular relevance in view of the recent observational data on Cassiopeia A. To study the nucleon-nucleus scattering problem in an {\it ab-initio} way, the optical potential in the momentum vector basis beyond the mean-field has been calculated employing the $\mathcal{T\times\rho}$ folding as the first step of the self-consistent Green's function method. The deuteron pole structure of $\mathcal{T}-$ matrix has been properly avoided using the spectral functions from the dispersive optical model. A comparison of the resulting real and imaginary part of the self-energy at 100 MeV with the corresponding dispersive-optical-model potentials shows reasonable agreement.

English (en)

#### Chair and Committee

Willem H. Dickhoff

#### Committee Members

Robert J. Charity, Kater W. Murch, Demetrios G. Sarantites, Lee G. Sobotka