Evidence for achions - or axions

Some electromagnetic showers have been observed at small angles (< 10) and low energies (< 1 GeV), in excess of what one would have expected from other sources, during a νsub(e) scattering experiment at the CERN PS. They do not resemble neutrino interactions. Rather they look like radiative decay gammas from a penetrating, neutral, light particle achion0, admixed to the neutrino beam. - Clear achion0 → 2γ decays have been seen in a 590 MeV proton beam dump experiment at SIN. The (14.5 +- 5) events point back to the source within the angular resolution (2 MeV/psub(e)); a flat background of 2.0+-0.4 comes from cosmic rays, another (3+-1) events are accelerator induced. The energy spectrum of either gamma is uniform, the average values (approximately 80 MeV) agree with each other. A 20 cm iron wall, placed at the beginning of the decay region, had little influence, but removed the effect, when shifted to its end. Analysing the effect in terms of axion production and decay, leads to a Higgs parameter X = 3.0+-0.3, and hence to an axion mass of (250+-25) keV. Interactions of such a particle might also explain the hadron-less lepton pairs (21 antiμ μ, 8 μ antie) observed during ν exposures at the CERN PS