Pseudoscalar - sterile neutrino interactions: reconciling the cosmos   with neutrino oscillations
  The Short BaseLine (SBL) neutrino oscillation anomalies hint at the presence of a sterile neutrino with a mass of around 1 eV. However, such a neutrino is incompatible with cosmological data, in particular observations of the Cosmic Microwave Background (CMB) anisotropies. However, this conclusion can change by invoking new physics. One possibility is to introduce a secret interaction in the sterile neutrino sector mediated by a light pseudoscalar. In this pseudoscalar model, CMB data prefer a sterile neutrino mass that is fully compatible with the mass ranges suggested by SBL anomalies. In addition, this model predicts a value of the Hubble parameter which is completely consistent with local measurements. 
Maria Archidiacono, Stefano Gariazzo, Carlo Giunti, Steen Hannestad,   Rasmus Hansen, Marco Laveder, Thomas Tram
astro-ph.CO hep-ph