Advanced search options

Advanced Search Options 🞨

Browse by author name (“Author name starts with…”).

Find ETDs with:

in
/  
in
/  
in
/  
in

Written in Published in Earliest date Latest date

Sorted by

Results per page:

Sorted by: relevance · author · university · dateNew search

You searched for subject:(Light front Quantization). Showing records 1 – 2 of 2 total matches.

Search Limiters

Last 2 Years | English Only

No search limiters apply to these results.

▼ Search Limiters


Iowa State University

1. Du, Weijie. Advances in ab initio approaches to nuclear structure, reaction and nucleonic dynamics.

Degree: 2019, Iowa State University

We calculate effective Hamiltonians and effective electroweak operators with the Okubo-Lee-Suzuki formalism for two-nucleon systems. Working within a harmonic oscillator basis, first without and then with a confining harmonic oscillator trap, we demonstrate the effects of renormalization on observables calculated for truncated basis spaces. We illustrate the renormalization effects for the root-mean-square point-proton radius, electric quadrupole moment, magnetic dipole moment, Gamow-Teller transition and neutrinoless double-beta decay operator using nucleon-nucleon interactions from chiral effective field theory. Renormalization effects tend to be larger in the weaker traps and smaller basis spaces suggesting applications to heavier nuclei with transitions dominated by weakly-bound nucleons would be subject to more significant renormalization effects within achievable basis spaces. We also develop an {\it ab initio}, non-perturbative, time-dependent basis function method to solve the nuclear structure and scattering problems in a unified manner. We apply this method to a test problem: the Coulomb excitation of a trapped deuteron by an impinging heavy ion. The states of the deuteron system are obtained by the {\it ab initio} nuclear structure calculation implementing a realistic inter-nucleon interaction with a weak external trap to localize the center of mass and to discretize the continuum. The evolution of the internal state of the deuteron system is directly solved using the equation of motion for the scattering. We analyze the excitation mechanism of the deuteron system by investigating its internal transition probabilities and observables as functions of the exposure time and the incident speed. In this investigation, the dynamics of the Coulomb excitation are revealed by the time evolution of the system's internal charge distribution. Finally, we present the first application of the Basis Light-Front Quantization method to a simple chiral model of the nucleon-pion system as a relativistic bound state for the physical proton. The light-front mass-squared matrix of the nucleon-pion system is obtained within a truncated basis. The mass and the corresponding light-front wave function (LFWF) of the proton are computed by numerical diagonalization of the resulting mass-squared matrix. With the boost invariant LFWF, we evaluate the proton's parton distribution function and Dirac form factor. An improved model, adopting phenomenological corrections for quark contributions, is implemented to calculate the proton's Dirac form factor. The resulting Dirac form factor agrees well with the experimental data below the squared transverse momentum transfer of 0.20 { GeV}2.

Subjects/Keywords: ab initio nuclear structure theory; light-front quantization; microscopic nuclear reaction theory; Physics

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Du, W. (2019). Advances in ab initio approaches to nuclear structure, reaction and nucleonic dynamics. (Thesis). Iowa State University. Retrieved from https://lib.dr.iastate.edu/etd/17674

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Du, Weijie. “Advances in ab initio approaches to nuclear structure, reaction and nucleonic dynamics.” 2019. Thesis, Iowa State University. Accessed November 28, 2020. https://lib.dr.iastate.edu/etd/17674.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Du, Weijie. “Advances in ab initio approaches to nuclear structure, reaction and nucleonic dynamics.” 2019. Web. 28 Nov 2020.

Vancouver:

Du W. Advances in ab initio approaches to nuclear structure, reaction and nucleonic dynamics. [Internet] [Thesis]. Iowa State University; 2019. [cited 2020 Nov 28]. Available from: https://lib.dr.iastate.edu/etd/17674.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Du W. Advances in ab initio approaches to nuclear structure, reaction and nucleonic dynamics. [Thesis]. Iowa State University; 2019. Available from: https://lib.dr.iastate.edu/etd/17674

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

2. Ghomeshi, Ramin Ghorbani. Pair Production and the Light-Front Vacuum.

Degree: Physics, 2013, Umeå University

Dominated by Heisenberg's uncertainty principle, vacuum is not quantum mechanically an empty void, i.e. virtual pairs of particles appear and disappear persistently. This nonlinearity subsequently provokes a number of phenomena which can only be practically observed by going to a high-intensity regime. Pair production beyond the so-called Sauter-Schwinger limit, which is roughly the field intensity threshold for pairs to show up copiously, is such a nonlinear vacuum phenomenon. From the viewpoint of Dirac's front form of Hamiltonian dynamics, however, vacuum turns out to be trivial. This triviality would suggest that Schwinger pair production is not possible. Of course, this is only up to zero modes. While the instant form of relativistic dynamics has already been at least theoretically well-played out, the way is still open for investigating the front form. The aim of this thesis is to explore the properties of such a contradictory aspect of quantum vacuum in two different forms of relativistic dynamics and hence to investigate the possibility of finding a way to resolve this ambiguity. This exercise is largely based on the application of field quantization to light-front dynamics. In this regard, some concepts within strong field theory and light-front quantization which are fundamental to our survey have been introduced, the order of magnitude of a few important quantum electrodynamical quantities have been fixed and the basic information on a small number of nonlinear vacuum phenomena has been identified. Light-front quantization of simple bosonic and fermionic systems, in particular, the light-front quantization of a fermion in a background electromagnetic field in (1+1) dimensions is given. The light-front vacuum appears to be trivial also in this particular case. Amongst all suggested methods to resolve the aforementioned ambiguity, the discrete light-cone quantization (DLCQ) method is applied to the Dirac equation in (1+1) dimensions. Furthermore, the Tomaras-Tsamis-Woodard (TTW) solution, which expresses a method to resolve the zero-mode issue, is also revisited. Finally, the path integral formulation of quantum mechanics is discussed and, as an alternative to TTW solution, it is proposed that the worldline approach in the light-front framework may shed light on different aspects of the TTW solution and give a clearer picture of the light-front vacuum and the pair production phenomenon on the light-front.

Subjects/Keywords: Strong-Field QED; Quantum Vacuum; Schwinger Pair Production Mechanism; Dirac Forms of Relativistic Dynamics; Light-front Quantization; Zero-mode Issue; DLCQ; Worldline Approach

…how different fields are quantized on the light-front. Different quantization methods on the… …light-front quantization, we start with the quantization of free fields. The evolution of every… …constrained and not dynamical; 19 Free theories on the light-front 20 • Other quantization… …relativistic dynamics revealed a theoretical issue. The light-front vacuum appeared to be trivial… …thesis concerns the Schwinger pair production phenomenon on the light-front, our survey starts… 

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Ghomeshi, R. G. (2013). Pair Production and the Light-Front Vacuum. (Thesis). Umeå University. Retrieved from http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-83444

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Ghomeshi, Ramin Ghorbani. “Pair Production and the Light-Front Vacuum.” 2013. Thesis, Umeå University. Accessed November 28, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-83444.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Ghomeshi, Ramin Ghorbani. “Pair Production and the Light-Front Vacuum.” 2013. Web. 28 Nov 2020.

Vancouver:

Ghomeshi RG. Pair Production and the Light-Front Vacuum. [Internet] [Thesis]. Umeå University; 2013. [cited 2020 Nov 28]. Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-83444.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Ghomeshi RG. Pair Production and the Light-Front Vacuum. [Thesis]. Umeå University; 2013. Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-83444

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.