Collective neutrino flavor transformation in supernovae

Journal Article · Fri Dec 15 04:00:00 EST 2006 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.74.123004· OSTI ID:20868164

Huaiyu, Duan; Fuller, George M; Yongzhong, Qian ^[1]

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1. Department of Physics, University of California, San Diego, La Jolla, California 92093-0319 (United States)

We examine coherent active-active channel neutrino flavor evolution in environments where neutrino-neutrino forward scattering can engender large-scale collective flavor transformation. We introduce the concept of neutrino flavor isospin which treats neutrinos and antineutrinos on an equal footing, and which facilitates the analysis of neutrino systems in terms of the spin precession analogy. We point out a key quantity, the ''total effective energy,'' which is conserved in several important regimes. Using this concept, we analyze collective neutrino and antineutrino flavor oscillation in the synchronized mode and what we term the bi-polar mode. We thereby are able to explain why large collective flavor mixing can develop on short time scales even when vacuum mixing angles are small in, e.g., a dense gas of initially pure {nu}{sub e} and {nu}{sub e} with an inverted neutrino mass hierarchy (an example of bi-polar oscillation). In the context of the spin precession analogy, we find that the corotating frame provides insights into more general systems, where either the synchronized or bi-polar mode could arise. For example, we use the corotating frame to demonstrate how large flavor mixing in the bi-polar mode can occur in the presence of a large and dominant matter background. We use the adiabatic condition to derive a simple criterion for determining whether the synchronized or bi-polar mode will occur. Based on this criterion, we predict that neutrinos and antineutrinos emitted from a protoneutron star in a core-collapse supernova event can experience synchronized and bi-polar flavor transformations in sequence before conventional Mikhyev-Smirnov-Wolfenstein flavor evolution takes over. This certainly will affect the analyses of future supernova neutrino signals, and might affect the treatment of shock reheating rates and nucleosynthesis depending on the depth at which collective transformation arises.

• OSTI ID: 20868164
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 12 Vol. 74; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANTINEUTRINOS
ELECTRON NEUTRINOS
EMISSION
EVOLUTION
FLAVOR MODEL
ISOSPIN
MIXING
NUCLEOSYNTHESIS
OSCILLATIONS
PRECESSION
REST MASS
SCATTERING
SPIN
SUPERNOVAE
TRANSFORMATIONS
WEINBERG ANGLE