Improved Determination of the ${}^{235}\text{U}$ and ${}^{239}\text{Pu}$ Reactor Antineutrino Cross Sections per Fission

Abstract

We present the results of a combined fit of the reactor antineutrino rates and the Daya Bay measurement of ${\sigma }_{f,235}$ and ${\sigma }_{f,239}$. The combined fit leads to a better determination of the two cross sections per fission: ${\sigma }_{f,235}=6.29\pm 0.08$ and ${\sigma }_{f,239}=4.24\pm 0.21$ in units of $10^{-43}{\text{cm}}^2/\text{fission}$, with respective uncertainties of about $1.2\%$ and $4.9\%$. Since the respective deviations from the theoretical cross sections per fission are $2.5\sigma$ and $0.7\sigma$, we conclude that, if the reactor antineutrino anomaly is not due to active-sterile neutrino oscillations, it is likely that it can be solved with a revaluation of the ${}^{235}\text{U}$ reactor antineutrino flux. However, the ${}^{238}\text{U}$, ${}^{239}\text{Pu}$, and ${}^{241}\text{Pu}$ fluxes, which have larger uncertainties, could also be significantly different from the theoretical predictions.

Comments: 4 pages; final version to be published in PRD