Reactor Fuel Fraction Information on the Antineutrino Anomaly

We analyzed the evolution data of the Daya Bay reactor neutrino experiment in terms of short-baseline active-sterile neutrino oscillations taking into account the theoretical uncertainties of the reactor antineutrino fluxes. We found that oscillations are disfavored at 2.6σ with respect to a suppression of the 235U reactor antineutrino flux and at 2.5σ with respect to variations of the 235U and 239Pu fluxes. On the other hand, the analysis of the rates of the short-baseline reactor neutrino experiments favor active-sterile neutrino oscillations and disfavor the suppression of the 235U flux at 3.1σ and variations of the 235U and 239Pu fluxes at 2.8σ. We also found that both the Daya Bay evolution data and the global rate data are well-fitted with composite hypotheses including variations of the 235U or 239Pu fluxes in addition to active-sterile neutrino oscillations. A combined analysis of the Daya Bay evolution data and the global rate data shows a slight preference for oscillations with respect to variations of the 235U and 239Pu fluxes. However, the best fits of the combined data are given by the composite models, with a preference for the model with an enhancement of the 239Pu flux and relatively large oscillations.