Lepton asymmetry in the primordial gravitational wave spectrum

Abstract

Effects of neutrino free streaming is evaluated on the primordial spectrum of gravitational radiation taking both neutrino chemical potential and masses into account. The former or the lepton asymmetry induces two competitive effects, namely, to increase anisotropic pressure, which damps the gravitational wave more, and to delay the matter-radiation equality time, which reduces the damping. The latter effect is more prominent and a large lepton asymmetry would reduce the damping. We may thereby be able to measure the magnitude of lepton asymmetry from the primordial gravitational wave spectrum.

14 pages, 5 figures

References in corpus (2)

• Improved Calculation of the Primordial Gravitational Wave Spectrum in the Standard Model
• Limit on the Neutrino Mass from the WMAP Three Year Data

Cited by in corpus (7)

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• Probing the properties of relic neutrinos using the cosmic microwave background, the Hubble Space Telescope and galaxy clusters
• Impact of anisotropic stress of free-streaming particles on gravitational waves induced by cosmological density perturbations
• WMAP 5-year constraints on lepton asymmetry and radiation energy density: Implications for Planck
• Probing neutrino interactions and dark radiation with gravitational waves
• Constraints on neutrino masses from WMAP5 and BBN in the lepton asymmetric universe
• Effective Search Templates for a Primordial Stochastic Gravitational Wave Background