Neutrino helicity oscillations in astrophysical environments: a many-body approach

N3AS-26-011

Neutrino helicity oscillations in astrophysical environments: a many-body approach

Yiheng Xu, Julien Froustey,, George M. Fuller, Lukáš Gráf, Amol V. Patwardhan.
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Abstract

Neutrino rest mass enables left-handed states to “flip” to right-handed states and vice versa. In-medium effects can enhance the probability for such spin-flip. We demonstrate that a full many-body calculation of this process in neutrino-dense environments can lead to spin-flip probabilities that exceed by orders of magnitude those calculated with mean-field treatments. We study simple configurations with a few neutrinos in well-defined momentum states, for which we show that the helicity conversion enhancement is connected to many-body momentum exchange. Such an effect would therefore be missed in a calculation that considers only forward processes. We speculate on the potential astrophysical implications of these results and the range of applicability of our calculation and its limitations.

Associated Fellows