New Supernova Constraints on Sterile-Neutrino Production.

Abstract

We consider the possibility that a light, sterile-neutrino species ${\ensuremath{\nu}}_{S}$ can be produced by ${\ensuremath{\nu}}_{e}$ scattering during the cooling of a proto-neutron star. If we parametrize the sterile-neutrino production cross section by a parameter $A$ as $\ensuremath{\sigma}({\ensuremath{\nu}}_{e}X\ensuremath{\rightarrow}{\ensuremath{\nu}}_{S}X)\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}A\ensuremath{\sigma}({\ensuremath{\nu}}_{e}X\ensuremath{\rightarrow}{\ensuremath{\nu}}_{e}X)$, where $X$ is an electron, neutron, or proton, we show that $A$ is constrained by limits to the conversion of ${\ensuremath{\nu}}_{e}$ to ${\ensuremath{\nu}}_{S}$ in the region between the sterile-neutrino trapping region and the electron-neutrino trapping region. This consideration excludes values of $A$ in the range ${10}^{\ensuremath{-}4}\ensuremath{\lesssim}A\ensuremath{\lesssim}{10}^{\ensuremath{-}1}$.