Speaker
Description
In extremely neutrino-dense environments like core-collapse supernovae or neutron star mergers, neutrinos interact with each other and undergo collective flavor oscillations with important physical consequences (e.g. on supernova explosion dynamics, nucleosynthesis, and the emitted neutrinos that reach Earth). However, a key ingredient in the standard approach to the problem, the mean-field approximation, is missing: a proper treatment of entanglement between neutrinos. In order to understand how entanglement can build up from the many, brief, pairwise interactions that neutrinos take part in, we proposed "once-in-a-lifetime encounter" (OILE) models for neutrino media. OILE models offer some insight into the connection between the mean-field approximation and many-body calculations of small numbers of neutrinos. In the limit of "very many, very brief" interactions, OILE models agree with the mean-field approximation, while in the opposite limit, OILE models agree with many-body calculations. OILE models also exhibit a smooth transition between these two limits, in which the neutrino system moves along a path of different mean-field "steady-precession" or "mixing equilibrium" states, and which can be described using the language of "miscidynamics".