2005/05/31 by D. Boyanovsky
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Neutrino Physics Research #Particle physics theoretical and experimental studies #astro-ph #hep-ph #hep-th #nucl-th
paper · pdf · doi:10.1103/physrevd.72.033004
published as Phys.Rev. D72 (2005) 033004 · 32 pages 16 figs. Discussion on screening corrections. Results unchanged to appear in Phys. Rev. D
arxiv created 2005/07/21 · openalex publication_date 2005/08/05 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Neutrino collective excitations are studied in the standard model at high temperatures below the symmetry breaking scale in the regime T\ensuremath≫MW,Z(T)\ensuremath≫gT. Two parameters determine the properties of the collective excitations: a mass scale m_\ensuremathν=gT/4 which determines the chirally symmetric gaps in the spectrum and \ensuremathΔ=MW2(T)/2m_\ensuremathνT. The spectrum consists of left-handed negative helicity quasiparticles, left-handed positive helicity quasiholes, and their respective antiparticles. For \ensuremathΔ<\ensuremathΔc=1.275\ensuremath⋯ there are two gapped quasiparticle branches and one gapless and two gapped quasihole branches, all but the higher gapped quasiparticle branches terminate at end points. For \ensuremathΔc<\ensuremathΔ<\ensuremathπ/2 the quasiparticle spectrum features a pitchfork bifurcation and for \ensuremathΔ>\ensuremathπ/2 the collective modes are gapless quasiparticles with dispersion relation below the light cone for k\ensuremath≪m_\ensuremathν approaching the free field limit for k\ensuremath≫m_\ensuremathν with a rapid crossover between the soft nonperturbative to the hard perturbative regimes for k\ensuremath∼m_\ensuremathν. The decay of the vector bosons leads to a width of the collective excitations of order g2 which is explicitly obtained in the limits k=0 and k\ensuremath≫m_\ensuremathν\ensuremathΔ. At high temperature this damping rate is shown to be competitive with or larger than the collisional damping rate of order GF2 for a wide range of neutrino energy.