Georg Raffelt, Max-Planck-Institut für Physik, München, Germany TAUP 2007, September 2007, Sendai, Japan Collective Flavor Oscillations Georg Raffelt, Max-Planck-Institut für Physik, München TAUP 2007, September 2007, Sendai, Japan Multi-Angle Effects in Collective Supernova Neutrino Oscillations

Georg Raffelt, Max-Planck-Institut für Physik, München, Germany TAUP 2007, September 2007, Sendai, Japan This talk is primarily based on our two recent papers G. Raffelt & G. Sigl G. Raffelt & G. Sigl Self-induced decoherence in dense neutrino gases Self-induced decoherence in dense neutrino gases Phys. Rev. D 75 (2007) , 15 pp Phys. Rev. D 75 (2007) , 15 pp [arXiv:hep-ph/ ] [arXiv:hep-ph/ ] A. Esteban-Pretel, S. Pastor, R. Tomàs, G.G. Raffelt & G. Sigl A. Esteban-Pretel, S. Pastor, R. Tomàs, G.G. Raffelt & G. Sigl Decoherence in supernova neutrino transformations Decoherence in supernova neutrino transformations suppressed by deleptonization suppressed by deleptonization arXiv: (astro-ph) arXiv: (astro-ph)

Georg Raffelt, Max-Planck-Institut für Physik, München, Germany TAUP 2007, September 2007, Sendai, Japan Self-Induced Flavor Oscillations of SN Neutrinos Survival probability e NormalHierarchy atm  m 2  13  close to Chooz limit InvertedHierarchy No nu-nu effect No MSWeffect MSWeffect Realistic Bipolarcollectiveoscillations(single-angle approximation) approximation) MSW Realistic nu-nu effect MSWeffect

Georg Raffelt, Max-Planck-Institut für Physik, München, Germany TAUP 2007, September 2007, Sendai, Japan Toy Supernova in “Single-Angle” Approximation Bipolar Oscillations Assume 80% anti-neutrinos Assume 80% anti-neutrinos Vacuum oscillation frequency Vacuum oscillation frequency  = 0.3 km  1  = 0.3 km  1 Neutrino-neutrino interaction Neutrino-neutrino interaction energy at nu sphere (r = 10 km) energy at nu sphere (r = 10 km)  = 0.3  10 5 km  1  = 0.3  10 5 km  1 Falls off approximately as r  4 Falls off approximately as r  4 (geometric flux dilution and nus (geometric flux dilution and nus become more co-linear) become more co-linear) Decline of oscillation amplitude explained in pendulum analogy by inreasing moment of inertia (Hannestad, Raffelt, Sigl & Wong astro-ph/ ) astro-ph/ )

Georg Raffelt, Max-Planck-Institut für Physik, München, Germany TAUP 2007, September 2007, Sendai, Japan Flux Term as a Source of Decoherence General two-flavor equations of motion, ignoring ordinary matter effects Axial symmetry around some direction, e.g., supernova radial direction Density (isotropic) term Responsible for usual collective phenomena (“self-maintained coherence”) coherence”) Flux term Responsible for kinematical decoherence (“self-induced decoherence”) decoherence”) Raffelt & Sigl, Self-induced decoherence in dense neutrino gases hep-ph/

Georg Raffelt, Max-Planck-Institut für Physik, München, Germany TAUP 2007, September 2007, Sendai, Japan Kinematical Decoherence - Symmetric Case InvertedHierarchy NormalHierarchy Isotropic (single angle) Large flux (“half isotropic”)

Georg Raffelt, Max-Planck-Institut für Physik, München, Germany TAUP 2007, September 2007, Sendai, Japan Examples for Kinematical Decoherence Smallasymmetry Largeasymmetry

Georg Raffelt, Max-Planck-Institut für Physik, München, Germany TAUP 2007, September 2007, Sendai, Japan End State of Polarization Vectors for Angular Modes

Georg Raffelt, Max-Planck-Institut für Physik, München, Germany TAUP 2007, September 2007, Sendai, Japan No kinematical decoherence (large asymmetry) Georg Raffelt, Max-Planck-Institut für Physik, München, Germany TAUP 2007, September 2007, Sendai, Japan

Georg Raffelt, Max-Planck-Institut für Physik, München, Germany TAUP 2007, September 2007, Sendai, Japan Kinematical decoherence (small asymmetry) Georg Raffelt, Max-Planck-Institut für Physik, München, Germany TAUP 2007, September 2007, Sendai, Japan

Georg Raffelt, Max-Planck-Institut für Physik, München, Germany TAUP 2007, September 2007, Sendai, Japan Critical Asymmetry for Decoherence Effective flux Asymmetry Esteban-Pretel, Pastor, Tomàs, Raffelt & Sigl: Decoherence in supernova neutrino transformations suppressed by deleptonization astro-ph/

Georg Raffelt, Max-Planck-Institut für Physik, München, Germany TAUP 2007, September 2007, Sendai, JapanConclusions For realistic supernova deleptonization fluxes, For realistic supernova deleptonization fluxes, kinematical decoherence among different angular modes kinematical decoherence among different angular modes likely irrelevant likely irrelevant Multi-angle effects apparently subdominant in practice Multi-angle effects apparently subdominant in practice Analytic understanding of this numerical result is missing Analytic understanding of this numerical result is missing (as with many other aspects of this nonlinear system) (as with many other aspects of this nonlinear system) Many other open questions, notably 3-flavor effects Many other open questions, notably 3-flavor effects

Georg Raffelt, Max-Planck-Institut für Physik, München, Germany TAUP 2007, September 2007, Sendai, Japan Papers on collective neutrino oscillations 1992 Flavor off-diagonal refractive index Numerical & analytic studies, but not much impact (nobody really understood) Flavor equilibration of cosmological neutrinos with chemical potential before BBN epoch SN neutrino oscillations and r-process nucleosynthesis (everybody missed the main point) point) “Bipolar” oscillations crucial for SN neutrinos Pantaleone, PLB 287(1992) 128 Samuel, Kostolecký & Pantaleone in various combinations: PLB 315:46 & 318:127 (1993), 385:159 (1996) PRD 48:1462 (1993), 49:1740 (1994), 52:621 & 3184 (1995), 53:5382 (1996), 58: (1998) Pastor, Raffelt & Semikoz, hep-ph/ Lunardini & Smirnov, hep-ph/ Dolgov et al., hep-ph/ Wong, hep-ph/ Abazajian, Beacom & Bell, astro-ph/ Pantaleone, astro-ph/ Qian & Fuller, astro-ph/ Sigl, astro-ph/ Pastor & Raffelt, astro-ph/ Balantekin & Yüksel, astro-ph/ Many papers by different groups.

Georg Raffelt, Max-Planck-Institut für Physik, München, Germany TAUP 2007, September 2007, Sendai, Japan Collective SN neutrino oscillations “Bipolar” collective transformations important, even for dense matter Duan, Fuller & Qian Duan, Fuller & Qian astro-ph/ astro-ph/ Numerical simulations Including multi-angle effects Including multi-angle effects Discovery of “spectral splits” Discovery of “spectral splits” Duan, Fuller, Carlson & Qian Duan, Fuller, Carlson & Qian astro-ph/ , astro-ph/ , Pendulum in flavor space Pendulum in flavor space Collective pair annihilation Collective pair annihilation Pure precession mode Pure precession mode Hannestad, Raffelt, Sigl & Wong Hannestad, Raffelt, Sigl & Wong astro-ph/ astro-ph/ Duan, Fuller, Carlson & Qian Duan, Fuller, Carlson & Qian astro-ph/ astro-ph/ Self-maintained coherence vs. self-induced decoherence caused by multi-angle effects Raffelt & Sigl, hep-ph/ Raffelt & Sigl, hep-ph/ Esteban-Pretel, Pastor, Tomas, Esteban-Pretel, Pastor, Tomas, Raffelt & Sigl, arXiv: Raffelt & Sigl, arXiv: Theory of “spectral splits” in terms of adiabatic evolution in rotating frame Raffelt & Smirnov, arXiv: Raffelt & Smirnov, arXiv: Duan, Fuller, Carlson & Qian Duan, Fuller, Carlson & Qian arXiv: , arXiv: , Independent numerical simulations Fogli, Lisi, Marrone & Mirizzi Fogli, Lisi, Marrone & Mirizzi arXiv: arXiv: