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muon decay asymmetry, magnetic moment, dimensional regularization

Liang, Yi

Supervisor and department: Andrzej Czarnecki Physics

Examining committee member and department: Alexander Penin Physics Kevin Beach Physics Vadim A. Kravchinsky Physics Davood Rafiei Computing Science Andrzej Czarnecki Physics

Department: Department of Physics

Specialization:

Date accepted: 2014-07-04T13:47:26Z

Graduation date: 2014-11

Degree: Doctor of Philosophy

Degree level: Doctoral

Abstract: Proper handling of divergent integrals is presented, first with the example of the photon-photon scattering. The classic result of this process was questioned, because the necessity of regularization in the classic calculation was not clear. This challenge has its counterpart. The standard result for the decay of the Higgs boson into two photons was also questioned for a similar reason. We have verified the classic result of the photon-photon scattering, and have confirmed the necessity of regularization. The need to implement the regularization procedure in the calculation of the Higgs decay process is tested with multiple calculational approaches. We find once again the standard result to be correct. We numerically study properties of leptonic systems. The first system is the positronium ion, a three-body system consisting of two electrons and a positron. The gyromagnetic factor of the positronium ion is determined with first relativistic corrections. We calculate the modified g -factor of this system for the first time. Our final topic is the computation of the spin asymmetry of the muon decay in perturbative QED. We point out that at the alpha squared level the asymmetry requires a careful definition due to multi-lepton final states and suggest to use familiar QCD techniques to define it in an infra-red safe way. We find that the TWIST measurement of the asymmetry is in excellent agreement with the Standard Model.

Language: English

DOI: doi:10.7939-R3Z60C944

Rights: Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.





Author: Liang, Yi

Source: https://era.library.ualberta.ca/


Teaser



Study of leptonic systems and loop calculation techniques by Yi Liang A thesis submitted in partial fulllment of the requirements for the degree of Doctor of Philosophy Department of Physics University of Alberta c  Yi Liang 2014 Abstract In the rst part of this thesis, proper handling of divergent integrals is presented, rst with the example of the photon-photon scattering.
The classic result of this process was questioned, because the necessity of regularization in the classic calculation was not clear.
This challenge has its counterpart.
The standard result for the decay of the Higgs boson into two photons was also questioned for a similar reason.
We have veried the classic result of the photon-photon scattering, and have conrmed the necessity of regularization. The need to implement the regularization procedure in the calculation of the Higgs decay process is tested with multiple calculational approaches.
We nd once again the standard result to be correct. In the second part of the thesis, we numerically study properties of leptonic systems.
The rst system is the positronium ion, a three-body system consisting of two electrons and a positron. The gyromagnetic factor of the positronium ion is determined with rst relativistic corrections. We calculate the modied g -factor of this system for the rst time.
Our nal topic is the com- putation of the spin asymmetry of the muon decay QED.
We point out that at O(α2 ) μ → eν̄e νμ through O(α2 ) in perturbative the asymmetry requires a careful denition due to multi- lepton nal states and suggest to use familiar QCD techniques to dene it in an infra-red safe way.
We nd that the TWIST measurement of the asymmetry is in excellent agreement with the Standard Model. ii Preface Chapter 2 of this thesis has been published as Yi Liang and Andrzej Czarnecki, -Theoretical Responses to Rays in the Gamma System,- Canadian Journal of Physics, vol.
90, 11. I was responsible for the calculat...





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