The European Physical Journal C

, 72:1974

First online:

Open Access This content is freely available online to anyone, anywhere at any time.

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

  • Zurab BerezhianiAffiliated withDipartimento di Fisica, Università dell’AquilaINFN, Laboratori Nazionali Gran Sasso Email author 
  • , Fabrizio NestiAffiliated withDipartimento di Fisica, Università dell’Aquila


Present experiments do not exclude that the neutron n oscillates, with an appreciable probability, into its invisible degenerate twin from a parallel world, the so-called mirror neutron n′. These oscillations were searched experimentally by monitoring the neutron losses in ultra-cold neutron traps, where they can be revealed by the magnetic field dependence of nn′ 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 dependence at more than 5σ away from the null hypothesis. This anomaly can be interpreted as oscillation of neutrons to mirror neutrons with a timescale of few seconds, in the presence of a mirror magnetic field order 0.1 G at the Earth. This result, if confirmed by future experiments, will have deepest consequences for fundamental particle physics, astrophysics and cosmology.