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The 3 + 1 dimensional lattice NJL model at non-zero baryon density. / David Nathan Walters

Swansea University Author: David Nathan Walters

Abstract

Lattice simulations of the 3+1 dimensional Nambu-Jona-Lasinio model are undertaken that provide non-perturbative evidence for the existence of a BCS superfluid phase in the low temperature, high density regime. Standard analytic methods are used to fit the model's free parameters to low energy...

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Published: 2003
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
URI: https://cronfa.swan.ac.uk/Record/cronfa42346
first_indexed 2018-08-02T18:54:29Z
last_indexed 2018-08-03T10:09:54Z
id cronfa42346
recordtype RisThesis
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spelling 2018-08-02T16:24:28.9165885 v2 42346 2018-08-02 The 3 + 1 dimensional lattice NJL model at non-zero baryon density. 232833e030c3a55b616bff7161bd790a NULL David Nathan Walters David Nathan Walters true true 2018-08-02 Lattice simulations of the 3+1 dimensional Nambu-Jona-Lasinio model are undertaken that provide non-perturbative evidence for the existence of a BCS superfluid phase in the low temperature, high density regime. Standard analytic methods are used to fit the model's free parameters to low energy vacuum phenomenology. The model is simulated numerically for a range of baryon chemical potential mu, with the introduction of a diquark source j to allow for the observation of spontaneous U(1) global symmetry breaking in a finite volume system. For mu &ge; 0.6 inverse lattice spacings and in the limit that j &rarr; 0, a non-zero diquark condensate, a vanishing diquark susceptibility ratio and an energy gap Delta &ne; 0 about the Fermi surface in the fermion dispersion relation are all consistent with the ground-state being that of a U(l)-broken BCS superfluid. The ratio between the gap at mu = 0.8 and the vacuum fermion mass is found to be 0.15(2). This is interpreted as tentative non-perturbative evidence for the existence of a colour superconducting phase in cold, dense QCD. The effects of simulating on a finite volume, and any conditions this places on the above conclusions, are investigated. Finally, the results of some initial studies at non-zero isospin chemical potential and the prospect of simulations at non-zero temperature are discussed. E-Thesis Theoretical physics. 31 12 2003 2003-12-31 COLLEGE NANME Physics COLLEGE CODE Swansea University Doctoral Ph.D 2018-08-02T16:24:28.9165885 2018-08-02T16:24:28.9165885 Faculty of Science and Engineering School of Biosciences, Geography and Physics - Physics David Nathan Walters NULL 1 0042346-02082018162447.pdf 10798054.pdf 2018-08-02T16:24:47.2470000 Output 9895857 application/pdf E-Thesis true 2018-08-02T16:24:47.2470000 false
title The 3 + 1 dimensional lattice NJL model at non-zero baryon density.
spellingShingle The 3 + 1 dimensional lattice NJL model at non-zero baryon density.
David Nathan Walters
title_short The 3 + 1 dimensional lattice NJL model at non-zero baryon density.
title_full The 3 + 1 dimensional lattice NJL model at non-zero baryon density.
title_fullStr The 3 + 1 dimensional lattice NJL model at non-zero baryon density.
title_full_unstemmed The 3 + 1 dimensional lattice NJL model at non-zero baryon density.
title_sort The 3 + 1 dimensional lattice NJL model at non-zero baryon density.
author_id_str_mv 232833e030c3a55b616bff7161bd790a
author_id_fullname_str_mv 232833e030c3a55b616bff7161bd790a_***_David Nathan Walters
author David Nathan Walters
author2 David Nathan Walters
format E-Thesis
publishDate 2003
institution Swansea University
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Biosciences, Geography and Physics - Physics{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Biosciences, Geography and Physics - Physics
document_store_str 1
active_str 0
description Lattice simulations of the 3+1 dimensional Nambu-Jona-Lasinio model are undertaken that provide non-perturbative evidence for the existence of a BCS superfluid phase in the low temperature, high density regime. Standard analytic methods are used to fit the model's free parameters to low energy vacuum phenomenology. The model is simulated numerically for a range of baryon chemical potential mu, with the introduction of a diquark source j to allow for the observation of spontaneous U(1) global symmetry breaking in a finite volume system. For mu &ge; 0.6 inverse lattice spacings and in the limit that j &rarr; 0, a non-zero diquark condensate, a vanishing diquark susceptibility ratio and an energy gap Delta &ne; 0 about the Fermi surface in the fermion dispersion relation are all consistent with the ground-state being that of a U(l)-broken BCS superfluid. The ratio between the gap at mu = 0.8 and the vacuum fermion mass is found to be 0.15(2). This is interpreted as tentative non-perturbative evidence for the existence of a colour superconducting phase in cold, dense QCD. The effects of simulating on a finite volume, and any conditions this places on the above conclusions, are investigated. Finally, the results of some initial studies at non-zero isospin chemical potential and the prospect of simulations at non-zero temperature are discussed.
published_date 2003-12-31T05:36:25Z
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score 11.096768

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