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Title of Thesis

Muhammad Anwar Mughal
Institute/University/Department Details
Department of Physics/ Quaid-i-Azam University Islamabad
Number of Pages
Keywords (Extracted from title, table of contents and abstract of thesis)
neutrino, solar neutrino problem, neutrino masses, neutrino oscillations, neutrino magnetic movement, faraday effect

The neutrino, its mysterious nature and its role in the understanding of structure of matter and its relationship to physics at large scale has been of profound recent interest. In the standard model of electroweak gauge theory and its minimal extension, the neutrino occupies a central place as a building block of matter.

The phenomenon of neutrino traversing and interacting with fields (matter and electromagnetic) in a medium has been under intense study for several years as neutrino dispersion in the framework of minimal standard model. Such a study is known to yield matter and magnetic field induced neutrino oscillations which possess far reaching implications for both terrestrial as well as extra-terrestrial physics.

For its applicability to and interest in solar neutrino problem, cosmology and other issues of astroparticle physics, we study, therefore, the neutrino dispersion through hot and dense medium in two model extensions of the standard model: one based on non-zero neutrino mass admitting the possibility of large enough magnetic moment for the neutrino yielding helicity-flip effects which result in spin-flavour oscillations. The other yielding neutrino oscillations within the context of the minimal extension of the standard model based on supersymmetry, the latter presumably being of more recent phenomenological interest.

We then present a simple study of an effect analogus to the classical Faraday effect for a dispersing neutrino de Broglie wave. This study leads to some understanding of the nature of neutrino in analogy with classical phenomenon and provides a natural, generic and consistent choice of the oscillations parameters corresponding to different oscillations scenarios.

In the study of v refraction in a minimal supersymmetric standard model with explicitly broken R-parity at finite temperature and density, it is found that sfermions coupled with fermions give rise to chirality conserving as well as chirality violating corrections to neutrino transitions. Some of the implications of these results to the solar neutrino problem, supernovae and early universe are discussed and compared with earlier works. We also study the issue of lepton-flavour violating Zo decays in minimal supersymmetric standard model. This result in the vacuum serves as an input in the framework of the FTD theory yielding further results of interest to astrophysics and cosmology. We have explicitly demonstrated that in this model present limits from low-energy processes can in principle accommodate these decays to values near the experimental bounds.

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4543.69 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
129.97 KB
2 1 Introduction 1
552.2 KB
  1.1 Neutrino Masses 4
  1.2 Solar Neutrino Problem And Neutrino Oscillations 7
  1.3 Neutrino Magnetic Movement Solution To SNP 14
  1.4 Field Theoretical Generalization Of Matter Induced Neutrino Oscillations 16
  1.5 Layout Of The Thesis 24
3 2 Neutrino Dispersion In A Minimally Extended Standard Model 26
248.11 KB
  2.1 Introduction 26
  2.2 Fukugita And Yanagida Model-A Minimal Extension Of The Standard Model 27
  2.3 Neutrino Dispersion In FY Model 28
  2.4 Contribution To Neutrino Self-Energy From Helicity-Flip Graphs In The FY Model 29
  2.5 Summary And Discussion 35
4 3 Neutrino Dispersion And The Faraday Effect 36
157.55 KB
  3.1 Introduction 36
  3.2 Neutrino Dispersion And Its Analogy With The Faraday Effect 37
  3.3 Implication In Solar Neutrino Problem 40
  3.4 Summary And Discussion 41
5 4 Minimal Supersymmetric Standard Model And Explicitly Broken R-Parity 42
184.89 KB
  4.1 Minimal Supersymmetric SM 42
  4.2 Explicitly Broken R-Parity 42
  4.3 Lepton-Flavour Violating Z o Decays 45
  4.4 Summary And Discussion
6 5 Neutrino Dispersion In MSSM With Explicitly Broken R-Parity Via L-Violation 50
277.27 KB
  5.1 Introduction 50
  5.2 Contribution To Self-Energy From Sfermion Mediating Graphs 52
  5.3 Birefringence And The MSW Resonance For Degenerate Neutrinos 55
  5.4 The Early Universe 59
  5.5 Summary And Discussion 61
7 6 Summary And Discussion 62
3163.41 KB
  6.1 Bibliography 66
  6.2 Figure Captions 76
  6.3 Table Captions 78
  6.4 Figures 79
  6.5 Tables 89
  6.6 Appendix-A 93