Nonlinear Oscillations of Supernova Neutrinos

Declaration This thesis is a presentation of my original research work. Wherever contributions of others are involved, every effort is made to indicate this clearly, with due reference to the literature, and acknowledgement of collaborative research and discussions. In my capacity as supervisor of the candidate's thesis, I certify that the above statements are true to the best of my knowledge. iii Acknowledgements As I submit this thesis, I feel compelled to express my gratitude to many people. Foremost, I gratefully acknowledge the guidance and support that I have recieved from Prof. Amol Dighe, my thesis advisor. I also thank my collaborators for a pleasant and satisfying experience of working together. I would like to express my gratitude to my teachers from Jadavpur University who inspired me to study physics. The faculty at TIFR have all been very helpful and friendly and I thank them for enjoyable and exciting courses, and stimulating discussions. Thanks are due to the DTP office staff and the institute administration staff for their help and unsurpassable efficiency in sorting out every trouble I took to them. I acknowledge the financial support recieved from Max Planck India Partner Group and from TIFR. I also wish to take this opportunity to convey my love and regards for my parents and my brother. Without their encouragement I could not have come this far. And finally, my heartfelt gratitude to all my friends, who made these years absolutely delightful. v Foreword The cosmos has remained a favorite laboratory to test the laws of fundamental physics-tests of the laws of gravity being the most well-known example. However, over the last century we have progressed from merely charting the gross motion of astrophysical objects, to observing more subtle phenomena associated with them. Many of these phenomena depend crucially on the laws of particle physics. As a result, astrophysics and particle physics are now connected more intimately than ever, with a promise to yield valuable insights into the laws of Nature. Neutrinos, being ubiquitous and weakly interacting, explore regions that are out of bounds to other particles, and are an ideal candidate to probe this deep connection. Our knowledge of neutrinos has seen a revolution of sorts in the last few decades, thanks to a number of experiments on atmospheric, solar and terrestrial neutrinos. These experiments lead us to believe that there are three flavors of massive neutrinos ν e , ν …