# 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 »

- 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}

}