Quantum Monte Carlo Studies of Strongly Interacting Fermionic Systems
abstract: In this dissertation two kinds of strongly interacting fermionic systems were studied: cold atomic gases and nucleon systems. In the first part I report T=0 diffusion Monte Carlo results for the ground-state and vortex excitation of unpolarized spin-1/2 fermions in a two-dimensional disk....
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ndltd-asu.edu-item-504332018-10-02T03:01:04Z Quantum Monte Carlo Studies of Strongly Interacting Fermionic Systems abstract: In this dissertation two kinds of strongly interacting fermionic systems were studied: cold atomic gases and nucleon systems. In the first part I report T=0 diffusion Monte Carlo results for the ground-state and vortex excitation of unpolarized spin-1/2 fermions in a two-dimensional disk. I investigate how vortex core structure properties behave over the BEC-BCS crossover. The vortex excitation energy, density profiles, and vortex core properties related to the current are calculated. A density suppression at the vortex core on the BCS side of the crossover and a depleted core on the BEC limit is found. Size-effect dependencies in the disk geometry were carefully studied. In the second part of this dissertation I turn my attention to a very interesting problem in nuclear physics. In most simulations of nonrelativistic nuclear systems, the wave functions are found by solving the many-body Schrödinger equations, and they describe the quantum-mechanical amplitudes of the nucleonic degrees of freedom. In those simulations the pionic contributions are encoded in nuclear potentials and electroweak currents, and they determine the low-momentum behavior. By contrast, in this work I present a novel quantum Monte Carlo formalism in which both relativistic pions and nonrelativistic nucleons are explicitly included in the quantum-mechanical states of the system. I report the renormalization of the nucleon mass as a function of the momentum cutoff, an Euclidean time density correlation function that deals with the short-time nucleon diffusion, and the pion cloud density and momentum distributions. In the two nucleon sector the interaction of two static nucleons at large distances reduces to the one-pion exchange potential, and I fit the low-energy constants of the contact interactions to reproduce the binding energy of the deuteron and two neutrons in finite volumes. I conclude by showing that the method can be readily applied to light-nuclei. Dissertation/Thesis Madeira, Lucas (Author) Schmidt, Kevin E (Advisor) Alarcon, Ricardo (Committee member) Beckstein, Oliver (Committee member) Erten, Onur (Committee member) Arizona State University (Publisher) Physics Nuclear physics and radiation Atomic physics Cold Fermi gases Nuclear structure Pions Quantum Monte Carlo eng 153 pages Doctoral Dissertation Physics 2018 Doctoral Dissertation http://hdl.handle.net/2286/R.I.50433 http://rightsstatements.org/vocab/InC/1.0/ 2018 |
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English |
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Doctoral Thesis |
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Physics Nuclear physics and radiation Atomic physics Cold Fermi gases Nuclear structure Pions Quantum Monte Carlo |
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Physics Nuclear physics and radiation Atomic physics Cold Fermi gases Nuclear structure Pions Quantum Monte Carlo Quantum Monte Carlo Studies of Strongly Interacting Fermionic Systems |
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abstract: In this dissertation two kinds of strongly interacting fermionic systems were studied: cold atomic gases and nucleon systems. In the first part I report T=0 diffusion Monte Carlo results for the ground-state and vortex excitation of unpolarized spin-1/2 fermions in a two-dimensional disk. I investigate how vortex core structure properties behave over the BEC-BCS crossover. The vortex excitation energy, density profiles, and vortex core properties related to the current are calculated. A density suppression at the vortex core on the BCS side of the crossover and a depleted core on the BEC limit is found. Size-effect dependencies in the disk geometry were carefully studied. In the second part of this dissertation I turn my attention to a very interesting problem in nuclear physics. In most simulations of nonrelativistic nuclear systems, the wave functions are found by solving the many-body Schrödinger equations, and they describe the quantum-mechanical amplitudes of the nucleonic degrees of freedom. In those simulations the pionic contributions are encoded in nuclear potentials and electroweak currents, and they determine the low-momentum behavior. By contrast, in this work I present a novel quantum Monte Carlo formalism in which both relativistic pions and nonrelativistic nucleons are explicitly included in the quantum-mechanical states of the system. I report the renormalization of the nucleon mass as a function of the momentum cutoff, an Euclidean time density correlation function that deals with the short-time nucleon diffusion, and the pion cloud density and momentum distributions. In the two nucleon sector the interaction of two static nucleons at large distances reduces to the one-pion exchange potential, and I fit the low-energy constants of the contact interactions to reproduce the binding energy of the deuteron and two neutrons in finite volumes. I conclude by showing that the method can be readily applied to light-nuclei. === Dissertation/Thesis === Doctoral Dissertation Physics 2018 |
author2 |
Madeira, Lucas (Author) |
author_facet |
Madeira, Lucas (Author) |
title |
Quantum Monte Carlo Studies of Strongly Interacting Fermionic Systems |
title_short |
Quantum Monte Carlo Studies of Strongly Interacting Fermionic Systems |
title_full |
Quantum Monte Carlo Studies of Strongly Interacting Fermionic Systems |
title_fullStr |
Quantum Monte Carlo Studies of Strongly Interacting Fermionic Systems |
title_full_unstemmed |
Quantum Monte Carlo Studies of Strongly Interacting Fermionic Systems |
title_sort |
quantum monte carlo studies of strongly interacting fermionic systems |
publishDate |
2018 |
url |
http://hdl.handle.net/2286/R.I.50433 |
_version_ |
1718756984722817024 |