Instabilities in neutrino systems induced by interactions with scalars

Journal Article · Tue Mar 15 00:00:00 EDT 2011 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.83.065023· OSTI ID:21537585

Sawyer, R F ^[1]

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1. Department of Physics, University of California at Santa Barbara, Santa Barbara, California 93106 (United States)

If there are scalar particles of small or moderate mass coupled very weakly to Dirac neutrinos, in a minimal way, then neutrino-anti-neutrino clouds of sufficient number density can experience an instability in which helicities are suddenly reversed. The predicted collective evolution is many orders of magnitude faster than given by cross section calculations. The instabilities are the analogue of the 'flavor-angle' instabilities (enabled by the Z exchange force) that may drive very rapid flavor exchange among the neutrinos that emerge from a supernova. These exchanges do require a tiny seed in addition to the scalar couplings, but the transition time is proportional to the negative of the logarithm of the seed strength, so that the size of this parameter is comparatively unimportant. For our actual estimates we use a tiny nonconservation of leptons; an alternative would be a neutrino magnetic moment in a small magnetic field. The possibility of a quantum fluctuation as a seed is also discussed. Operating in the mode of putting limits on the coupling constant of the scalar field, for the most minimal coupling scheme, with independent couplings to all three {nu}, we find a rough limit on the dimensionless coupling constant for a neutrino-flavor independent coupling of G<10{sup -10}, to avoid the effective number of light neutrinos in the early universe being essentially six. If, on the other hand, we wish to fine-tune the model to give a more modest excess (over three) in the effective neutrino number, as may be needed according to recent WMAP analyses, it is easy to do so.

• OSTI ID: 21537585
• Journal Information: Physical Review. D, Particles Fields, Vol. 83, Issue 6; Other Information: DOI: 10.1103/PhysRevD.83.065023; (c) 2011 American Institute of Physics; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANTINEUTRINOS
COUPLING
COUPLING CONSTANTS
CROSS SECTIONS
DENSITY
EVOLUTION
FLAVOR MODEL
FLUCTUATIONS
HELICITY
INSTABILITY
INTERACTIONS
MAGNETIC FIELDS
MAGNETIC MOMENTS
MASS
NEUTRINOS
SCALAR FIELDS
UNIVERSE
ANTILEPTONS
ANTIMATTER
ANTIPARTICLES
COMPOSITE MODELS
ELEMENTARY PARTICLES
FERMIONS
LEPTONS
MASSLESS PARTICLES
MATHEMATICAL MODELS
MATTER
PARTICLE MODELS
PARTICLE PROPERTIES
PHYSICAL PROPERTIES
QUARK MODEL
VARIATIONS