Magnetic anomaly in UCN trapping: signal for neutron oscillations to parallel world?

Present experiments do not exclude that the neu- tron n oscillates, with an appreciable probability, into its in- visible degenerate twin from a parallel world, the so-called mirror neutron n′. These oscillations were searched experi- mentally by monitoring the neutron losses in ultra-cold neu- tron traps, where they can be revealed by the magnetic field dependence of n–n′ transition probability. In this work we reanalyze the experimental data acquired by the group of A.P. Serebrov at Institute Laue–Langevin, and find a depen- dence at more than 5σ away from the null hypothesis. This anomaly can be interpreted as oscillation of neutrons to mir- ror neutrons with a timescale of few seconds, in the presence of a mirror magnetic field order 0.1 G at the Earth. This re- sult, if confirmed by future experiments, will have deepest consequences for fundamental particle physics, astrophysics and cosmology.