Improved constraints on lepton asymmetry from the cosmic microwave background

Isabel M. Oldengott; Dominik J. Schwarz

doi:10.1209/0295-5075/119/29001

paper

Improved constraints on lepton asymmetry from the cosmic microwave background

arXiv:1706.01705 · doi:10.1209/0295-5075/119/29001

Abstract

A cosmic lepton asymmetry $η_{l} = (n_{l} - n_{l ˉ}) / n_{γ}$ affects the primordial helium abundance and the expansion rate of the early Universe. Both of these effects have an impact on the anisotropies of the cosmic microwave background (CMB). We derive constraints on the neutrino chemical potentials from the Planck 2015 data, assuming equal lepton flavour asymmetries and negligible neutrino masses. We find $ξ = - 0.00 2_{- 0.111}^{+ 0.114}$ (95\% CL) for the chemical potentials, which corresponds to $- 0.085 \leq η_{l} \leq 0.084$ . Our constraints on the lepton asymmetry are significantly stronger than previous constraints from CMB data analysis and we argue that they are more robust than those from primordial light element abundances. The resulting constraints on the primordial helium and deuterium abundances are consistent with those from direct measurements.

arXiv comment6 pages, 3 figures; extended discussion about the literature, accepted by EPL

Improved constraints on lepton asymmetry from the cosmic microwave background

Abstract

References in corpus (31)

Cited by in corpus (43)