Reentrant violation of special relativity in the low-energy corner

In the effective relativistic quantum field theories, the energy region in which special relativity holds can be sandwiched from both the high- and lo w-energy sides by domains where special relativity is violated. An example is provided by He-3-A, where the relativistic quantum field theory emerges as the effective theory. The reentrant violation of special relativity in t he ultralow-energy corner is accompanied by the redistribution of the momen tum-space topological charges among the fermionic flavors. At this ultralow energy, an exotic massless fermion with topological charge N-3 = 2 arises whose energy spectrum mixes classical and relativistic behaviors. This effe ct can lead to neutrino oscillations, if neutrino flavors are still massles s on this energy scale. (C) 2001 MAIK "Nauka/Interperiodica".