Search for a new gauge boson in neutral pion decays

A search was made for a new light gauge boson X which might be produced decay from neutral pions generated by 450 GeV protons in the CERN SPS neutrino target. The X’s would penetrate the downstream shielding and be observed in the NOMAD detector via the Primakoff effect. 20 candidate events with energy between 8 and 140 GeV were found from the analysis of neutrino data. This number is in agreement with the expectation of 18. background events from standard neutrino processes.