In this study, a dense neutrino medium such as that inside a core-collapse supernova can experience collective flavor conversion or oscillations because of the neutral-current weak interaction among the neutrinos. This phenomenon has been studied in a restricted, stationary supernova model which possesses the (spatial) spherical symmetry about the center of the supernova and the (directional) axial symmetry around the radial direction. Recently it has been shown that these spatial and directional symmetries can be broken spontaneously by collective neutrino oscillations. In this letter we analyze the neutrino flavor instabilities in a time-dependent supernova model. Our results show that collective neutrino oscillations start at approximately the same radius in both the stationary and time-dependent supernova models unless there exist very rapid variations in local physical conditions on timescales of a few microseconds or shorter. Our results also suggest that collective neutrino oscillations can vary rapidly with time in the regimes where they do occur which need to be studied in time-dependent supernova models.

Neutrinos are fundamental particles which only interact via gravity and the weak force, which makes them uniquely hard to observe and study experimentally. There are three flavors in the Standard Model (SM) of particle physics, however there has been experimental results that suggest the existence of a theoretical fourth neutrino flavor, called the sterile neutrino, with the three flavors in the SM being active neutrinos. Sterile neutrinos would interact only via the gravity, which means we would only be able to detect them through neutrino oscillations. A potential environment in which active to sterile oscillations could be highly probable to occur is supernovae, due to a large amount of neutrinos being created through nuclear fusion as well as high and varying densities of matter through which the neutrinos propagate. To investigate the evolution of neutrinos in supernova environments and the possibility of stimulated sterile neutrino oscillations, we create a code to simulate the evolution of neutrinos through a supernova density profile.

Contents:Solar Neutrinos:The Latest Solar Neutrino Results in Super-Kamiokande (Y Koshio)Weak Current in Deuterium (T Sato)Solar Neutrino Phenomenology and Future:Solar Neutrino Oscillations (M C Gonzalez-Garcia)The Status of Resonant Spin Flavor Precession (C S Lim)Atmospheric Neutrinos:Status of the Atmospheric Neutrino Studies (M D Messier)Cosmic Ray Measurements for Atmospheric Neutrino with BESS-TeV (K Abe)Oscillation Phenomenology I:Calculations of the Atmospheric ν Fluxes (P Lipari)Three-Flavor Analysis of Atmospheric and Solar Neutrinos (A Marrone)Absolute Neutrino Mass:Neutrinoless Double Beta Decay and Neutrino Oscillations (H V Klapdor-Kleingrothaus)Accelerator Neutrinos, CPV:The MINOS Experiment (M D Messier)The JHF-Kamioka Neutrino Project (T Kajita)Models and GUTs:Proton Decay in the Semi-Simple Unification Model (T Watari)Leptogenesis via LHu Flat Direction (M Fujii)Lepton Flavor Violation:Probing Physics Beyond the Standard Model from Lepton Sector (J Hisano)Oscillation Phenomenology II:Four Puzzles of Neutrino Mixing (S M Barr)Supernova Neutrinos:Supernova Neutrinos (J F Beacom)and other papers Readership: Researchers in high energy physics. Keywords:Solar Neutrinos;Atmospheric Neutrinos;Oscillation Phenomenology;Neutrino Mass;Accelerator Neutrinos;CP Violation;GUTs;Lepton Flavor Violation;Supernova Neutrinos

The neutrino-neutrino interaction is a tree-level process of the Standard Model that is still yet to be observed. Moreover, in tandem with vacuum flavor oscillations and given a sufficiently large density of neutrinos, this interaction can substantially impact the flavor content of the neutrino ensemble - an interplay of one- and two-body neutrino behavior known as "collective neutrino oscillations." While mean-field approximations have been used to gather a basic intuition for the collective behavior of a neutrino ensemble, little is known about how particle correlations scale with the size of the neutrino ensemble for realistic physical parameters in environments such as supernovae (SNe) and the Early Universe (EU). We therefore present a many-body approach to studying collective neutrino interactions in two flavors (i.e., e and x) for the forward scattering of N neutrinos. We present results for N8́ơ10 and discuss implications of our work for observable corrections to mean-field predictions of neutrino flavor spectra in SNe fluxes and nuclear isotope abundances.

This handbook is a comprehensive, systematic source of modern nuclear physics. It aims to summarize experimental and theoretical discoveries and an understanding of unstable nuclei and their exotic structures, which were opened up by the development of radioactive ion (RI) beam in the late 1980s. The handbook comprises three major parts. In the first part, the experiments and measured facts are well organized and reviewed. The second part summarizes recognized theories to explain the experimental facts introduced in the first part. Reflecting recent synergistic progress involving both experiment and theory, the chapters both parts are mutually related. The last part focuses on cosmo-nuclear physics—one of the mainstream subjects in modern nuclear physics. Those comprehensive topics are presented concisely. Supported by introductory reviews, all chapters are designed to present their topics in a manner accessible to readers at the graduate level. The book therefore serves as a valuable source for beginners as well, helping them to learn modern nuclear physics.

"Neutrinos in Particle Physics, Astronomy and Cosmology" provides a comprehensive and up-to-date introduction to neutrino physics, neutrino astronomy and neutrino cosmology. The intrinsic properties and fundamental interactions of neutrinos are described, as is the phenomenology of lepton flavor mixing, seesaw mechanisms and neutrino oscillations. The cosmic neutrino background, stellar neutrinos, supernova neutrinos and ultrahigh-energy cosmic neutrinos, together with the cosmological matter-antimatter asymmetry and other roles of massive neutrinos in cosmology, are discussed in detail. This book is intended for researchers and graduate students in the fields of particle physics, particle astrophysics and cosmology. Dr. Zhizhong Xing is a professor at the Institute of High Energy Physics, Chinese Academy of Sciences, China; Dr. Shun Zhou is currently a postdoctoral fellow at the Max Planck Institute for Physics, Germany.