Decoherence in supernova neutrino transformations suppressed by deleptonization

摘要: In the dense-neutrino region at 50-400 km above neutrino sphere in a supernova, neutrino-neutrino interactions cause large flavor transformations. We study when multiangle nature of trajectories leads to decoherence between different angular modes. consider two-flavor mixing scenario {nu}{sub e} and another x} assume usual hierarchy F{sub e}}>F{sub x}}=F{sub x}} for number fluxes. define {epsilon}=(F{sub e}}-F{sub e}})/(F{sub x}}) as measure deleptonization flux which is one crucial parameter. The transition quasi-single-angle behavior abrupt function {epsilon}. For typical choices other parameters, suppressed {epsilon} > or approx. 0.3, but much smaller asymmetry suffices if mass normal angle small. critical depends logarithmically on luminosity. realistic supernova scenario, probably enough suppress decoherence.