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Title: Production of a sterile species: Quantum kinetics

Abstract

Production of a sterile species is studied within an effective model of active-sterile neutrino mixing in a medium in thermal equilibrium. The quantum kinetic equations for the distribution functions and coherences are obtained from two independent methods: the effective action and the quantum master equation. The decoherence time scale for active-sterile oscillations is tau(dec)=2/Gamma(aa), but the evolution of the distribution functions is determined by the two different time scales associated with the damping rates of the quasiparticle modes in the medium: Gamma(1)=Gamma(aa)cos^2theta(m); Gamma(2)=Gamma(aa)sin^2theta(m) where Gamma(aa) is the interaction rate of the active species in the absence of mixing and theta(m) the mixing angle in the medium. These two time scales are widely different away from Mikheyev-Smirnov-Wolfenstein resonances and preclude the kinetic description of active-sterile production in terms of a simple rate equation. We give the complete set of quantum kinetic equations for the active and sterile populations and coherences and discuss in detail the various approximations. A generalization of the active-sterile transition probability in a medium is provided via the quantum master equation. We derive explicitly the usual quantum kinetic equations in terms of the"polarization vector" and show their equivalence to those obtained from the quantum master equation and effectivemore » action.« less

Authors:
; ;
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
Physics Division
OSTI Identifier:
934482
Report Number(s):
LBNL-395E
TRN: US0803801
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review D; Journal Volume: 76; Related Information: Journal Publication Date: 16 October 2007
Country of Publication:
United States
Language:
English
Subject:
72; APPROXIMATIONS; DAMPING; DISTRIBUTION FUNCTIONS; KINETIC EQUATIONS; KINETICS; NEUTRINOS; OSCILLATIONS; POLARIZATION; PROBABILITY; PRODUCTION; THERMAL EQUILIBRIUM

Citation Formats

Ho, Chiu Man, Boyanovsky, D., and Ho, C.M.. Production of a sterile species: Quantum kinetics. United States: N. p., 2007. Web.
Ho, Chiu Man, Boyanovsky, D., & Ho, C.M.. Production of a sterile species: Quantum kinetics. United States.
Ho, Chiu Man, Boyanovsky, D., and Ho, C.M.. Mon . "Production of a sterile species: Quantum kinetics". United States. doi:. https://www.osti.gov/servlets/purl/934482.
@article{osti_934482,
title = {Production of a sterile species: Quantum kinetics},
author = {Ho, Chiu Man and Boyanovsky, D. and Ho, C.M.},
abstractNote = {Production of a sterile species is studied within an effective model of active-sterile neutrino mixing in a medium in thermal equilibrium. The quantum kinetic equations for the distribution functions and coherences are obtained from two independent methods: the effective action and the quantum master equation. The decoherence time scale for active-sterile oscillations is tau(dec)=2/Gamma(aa), but the evolution of the distribution functions is determined by the two different time scales associated with the damping rates of the quasiparticle modes in the medium: Gamma(1)=Gamma(aa)cos^2theta(m); Gamma(2)=Gamma(aa)sin^2theta(m) where Gamma(aa) is the interaction rate of the active species in the absence of mixing and theta(m) the mixing angle in the medium. These two time scales are widely different away from Mikheyev-Smirnov-Wolfenstein resonances and preclude the kinetic description of active-sterile production in terms of a simple rate equation. We give the complete set of quantum kinetic equations for the active and sterile populations and coherences and discuss in detail the various approximations. A generalization of the active-sterile transition probability in a medium is provided via the quantum master equation. We derive explicitly the usual quantum kinetic equations in terms of the"polarization vector" and show their equivalence to those obtained from the quantum master equation and effective action.},
doi = {},
journal = {Physical Review D},
number = ,
volume = 76,
place = {United States},
year = {Mon Apr 23 00:00:00 EDT 2007},
month = {Mon Apr 23 00:00:00 EDT 2007}
}
  • Production of a sterile species is studied within an effective model of active-sterile neutrino mixing in a medium in thermal equilibrium. The quantum kinetic equations for the distribution functions and coherences are obtained from two independent methods: the effective action and the quantum master equation. The decoherence time scale for active-sterile oscillations is {tau}{sub dec}=2/{gamma}{sub aa}, but the evolution of the distribution functions is determined by the two different time scales associated with the damping rates of the quasiparticle modes in the medium: {gamma}{sub 1}={gamma}{sub aa}cos{sup 2}{theta}{sub m}; {gamma}{sub 2}={gamma}{sub aa}sin{sup 2}{theta}{sub m} where {gamma}{sub aa} is the interaction ratemore » of the active species in the absence of mixing and {theta}{sub m} the mixing angle in the medium. These two time scales are widely different away from Mikheyev-Smirnov-Wolfenstein resonances and preclude the kinetic description of active-sterile production in terms of a simple rate equation. We give the complete set of quantum kinetic equations for the active and sterile populations and coherences and discuss in detail the various approximations. A generalization of the active-sterile transition probability in a medium is provided via the quantum master equation. We derive explicitly the usual quantum kinetic equations in terms of the 'polarization vector' and show their equivalence to those obtained from the quantum master equation and effective action.« less
  • The production of a sterile species via active-sterile mixing in a thermal medium is studied in an exactly solvable model. The exact time evolution of the sterile distribution function is determined by the dispersion relations and damping rates {gamma}{sub 1,2} for the quasiparticle modes. These depend on {gamma}-tilde={gamma}{sub aa}/2{delta}E, with {gamma}{sub aa} the interaction rate of the active species in absence of mixing and {delta}E the oscillation frequency in the medium without damping. {gamma}-tilde <<1, {gamma}-tilde >>1 describe the weak and strong damping limits, respectively. For {gamma}-tilde <<1, {gamma}{sub 1}={gamma}{sub aa}cos{sup 2}{theta}{sub m}; {gamma}{sub 2}={gamma}{sub aa}sin{sup 2}{theta}{sub m} where {theta}{submore » m} is the mixing angle in the medium and the sterile distribution function does not obey a simple rate equation. For {gamma}-tilde >>1, {gamma}{sub 1}={gamma}{sub aa} and {gamma}{sub 2}={gamma}{sub aa}sin{sup 2}2{theta}{sub m}/4{gamma}-tilde{sup 2}, is the sterile production rate. In this regime sterile production is suppressed and the oscillation frequency vanishes at an Mikheyev-Smirnov-Wolfenstein (MSW) resonance, with a breakdown of adiabaticity. These are consequences of quantum Zeno suppression. For active neutrinos with standard model interactions the strong damping limit is only available near an MSW resonance if sin2{theta}<<{alpha}{sub w} with {theta} the vacuum mixing angle. The full set of quantum kinetic equations for sterile production for arbitrary {gamma}-tilde are obtained from the quantum master equation. Cosmological resonant sterile neutrino production is quantum Zeno suppressed relieving potential uncertainties associated with the QCD phase transition.« less
  • A simple unifying mass matrix is presented for the three active and one sterile neutrinos {nu}{sub e}, {nu}{sub {mu}}, {nu}{sub {tau}}, and {nu}{sub s}, using an extension of the radiative mechanism proposed some time ago by Zee. The total neutrino-oscillation data are explained by the scheme {nu}{sub e}{leftrightarrow}{nu}{sub s} (solar), {nu}{sub {mu}}{leftrightarrow}{nu}{sub {tau}} (atmospheric) and {nu}{sub e}{leftrightarrow}{nu}{sub {mu}} (LSND). We obtain the interesting approximate relationship ({Delta}m{sup 2}){sub atm}{approx_equal}2[({Delta}m{sup 2}){sub solar}({Delta}m{sup 2}){sub LSND}]{sup 1/2} which is well satisfied by the data. {copyright} {ital 1998} {ital The American Physical Society}