Construction and analysis of a simplified many-body neutrino model

摘要: In dense neutrino systems, such as found in the early Universe, or near a supernova core, flavor evolution is affected by coherent neutrino-neutrino scattering. It has been recently suggested that many-particle quantum entanglement effects may play an essential role these potentially invalidating traditional description terms of set single-particle equations. We model system interacting spins, following earlier work which showed spin can some cases be solved exactly [A. Friedland and C. Lunardini, J. High Energy Phys. 10 (2003) 043.]. extend this constructing exact analytical solution to more general system, including initial states with asymmetric distribution and, moreover, not necessarily aligned along same axis. Our exhibits rich behaviors, oscillations dephasing transition from classical regimes. argue captures entire behavior while capture some, but all, incoherent evolution. By comparing we find no evidencemore » for violation accepted one-body description, though argument involves subtleties appreciated before. The analysis paper apply other two-state systems beyond field.« less