Physical Review Letters
The MINERvA experiment observes an excess of events containing electromagnetic showers relative to the expectation from Monte Carlo simulations in neutral-current neutrino interactions with mean beam energy of 4.5 GeV on a hydrocarbon target. The excess is characterized and found to be consistent with neutral-current pi(0) production with a broad energy distribution peaking at 7 GeV and a total cross section of 0.26 +/- 0.02(stat.) +/- 0.08(sys.) x 10(-39) cm(2). The angular distribution, electromagnetic shower energy, and spatial distribution of the energy depositions of the excess are consistent with expectations from neutrino neutral-current diffractive pi(0) production from hydrogen in the hydrocarbon target. These data comprise the first direct experimental observation and constraint for a reaction that poses an important background process in neutrino-oscillation experiments searching for nu(mu) to nu(e) oscillations.
Wolcott, J., Aliaga, L., Altinok, O., Bercellie, A., Betancourt, M., Bodek, A., ... & Chvojka, J. (2016). Evidence for Neutral-Current Diffractive π 0 Production from Hydrogen in Neutrino Interactions on Hydrocarbon. Physical review letters, 117(11), 111801.