Non equilibrium dynamics of mixing, oscillations and equilibration: a model study
| dc.creator | Boyanovsky, D. | |
| dc.creator | Ho, C. M. | |
| dc.date | 2006-10-03 | |
| dc.date | 2007-05-11 | |
| dc.date.accessioned | 2026-07-07T10:25:35Z | |
| dc.date.available | 2026-07-07T10:25:35Z | |
| dc.description | The non-equilibrium dynamics of mixing, oscillations and equilibration is studied in a field theory of flavored neutral mesons that effectively models two flavors of mixed neutrinos, in interaction with other mesons that represent a thermal bath of hadrons or quarks and charged leptons. This model describes the general features of neutrino mixing and relaxation via charged currents in a medium. The reduced density matrix and the non-equilibrium effective action that describes the propagation of neutrinos is obtained by integrating out the bath degrees of freedom. We obtain the dispersion relations, mixing angles and relaxation rates of ``neutrino'' quasiparticles. The dispersion relations and mixing angles are of the same form as those of neutrinos in the medium, and the relaxation rates are given by $Γ_1(k) = Γ_{ee}(k) \cos^2θ_m(k)+Γ_{μμ}(k)\sin^2θ_m(k) ; Γ_2(k)= Γ_{μμ}(k) \cos^2θ_m(k)+Γ_{ee}(k)\sin^2θ_m(k) $ where $Γ_{αα}(k)$ are the relaxation rates of the flavor fields in \emph{absence} of mixing, and $θ_m(k)$ is the mixing angle in the medium. A Weisskopf-Wigner approximation that describes the asymptotic time evolution in terms of a non-hermitian Hamiltonian is derived. At long time $>>Γ^{-1}_{1,2}$ ``neutrinos'' equilibrate with the bath. The equilibrium density matrix is nearly diagonal in the basis of eigenstates of an \emph{effective Hamiltonian that includes self-energy corrections in the medium}. The equilibration of ``sterile neutrinos'' via active-sterile mixing is discussed. | |
| dc.description | 28 pages, 3 figures, version to appear in PRD | |
| dc.identifier | https://arxiv.org/abs/hep-ph/0610036 | |
| dc.identifier | http://arxiv.org/abs/hep-ph/0610036 | |
| dc.identifier | Phys.Rev.D75:085004,2007 | |
| dc.identifier | doi:10.1103/PhysRevD.75.085004 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/176589 | |
| dc.subject | High Energy Physics - Phenomenology | |
| dc.title | Non equilibrium dynamics of mixing, oscillations and equilibration: a model study | |
| dc.type | text |