Can neutrino-induced photon production explain the low energy excess in MiniBooNE?

Abstract

This report summarizes our study of Neutral Current (NC)-induced photon production in Mini-BooNE, as motivated by the low energy excess in this experiment [A. A. Aquilar-Arevalo et al. (MiniBooNE Collaboration), Phys. Rev. Lett. 98, 231801 (2007); 103, 111801 (2009)]. It was proposed that NC photon production with two anomalous photon-Z boson-vector meson couplings might explain the excess. However, our computed event numbers in both neutrino and antineutrino runs are consistent with the previous MiniBooNE estimate that is based on their pion production measurement. Various nuclear effects discussed in our previous works, including nucleon Fermi motion, Pauli blocking, and the ∆ resonance broadening in the nucleus, are taken into account. Uncertainty due to the two anomalous terms and nuclear effects are studied in a conservative way.

Recent advances and open questions in neutrino-induced quasi-elastic scattering and single photon production

“…For reconstructed neutrino energies relevant to MiniBooNE, there is also good agreement with the predictions used by MiniBooNE as shown in Table 5 [109]. Thus, it appears that the convergence of these predictions with more sophisticated treatments of nuclear effects, and their agreement with the initial estimates used by MiniBooNE, dampen earlier speculations indicating that the MiniBooNE electron neutrino excess is due to mismodeling the NC γ process.…”

“…The updated theoretical view of the inclusive CCQE process is much more complicated than past assumptions based primarily on a Relativistic Fermi Gas (RFG) model of the nucleus supplemented with the impulse approximation (IA). [109], and Hill [98] and compared to three neutrino event generators. The NUANCE curve corresponds to the MiniBooNE estimate for this process.…”

Low-energy photon production in neutrino neutral-current interactions

“…This was found [12,13] to be an overestimate, as a result of form factor and recoil effects, with ∆ excitation and decay providing a dominant photon source, but the nominal value g ω = 10 was retained. Corrections for efficiency [17,19] further reduced the expected signal. We shall use a 1 dominance of the weak neutral current to find an independent extimate of g ω , finding a value close to 7.…”

“…This strengthens the conclusions of Refs. [9][10][11][12][13][14][15][17][18][19] that if the MiniBooNE signal is indeed found to be photons, the WZW anomaly is unlikely to be their dominant source.…”

“…Although neutral-current nucleon excitation followed by photon emission was originally suggested as a source of the signal, it was found insufficient as well in Refs. [14][15][16][17][18][19]. A comprehensive review of neutrino-induced quasielastic scattering and single photon production is given in a workshop summary [20].…”