Evolution of Tau-Neutrino Lepton Number in Protoneutron Stars due to Active-Sterile Neutrino Mixing

Anupam Ray, Yong-Zhong Qian.


We present an approximate treatment of the mixing between \nu_{\tau} (\bar\nu_{\tau}) and a sterile species \nu_s (\bar\nu_s) with a vacuum mass-squared difference of \sim 102-103 keV2 in protoneutron stars created in core-collapse supernovae. Including production of sterile neutrinos through both resonant flavor conversion and collisions, we track the evolution of the \nu_{\tau} lepton number due to both escape of sterile neutrinos and diffusion. Our approach provides a reasonable treatment of the pertinent processes discussed in previous studies and serves a pedagogical purpose to elucidate the relevant physics. We also discuss refinements needed to study more accurately how flavor mixing with sterile neutrinos affects protoneutron star evolution.

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