engleski

Self-consistent calculation of the reactor antineutrino spectra including forbidden transitions

With the goal of determining the theta(13) neutrino oscillation mixing angle, the measurements of reactor antineutrino fluxes at the Double Chooz, RENO and Daya Bay experimental facilities have uncovered a systematic discrepancy between the number of observed events and theoretical expectations. In the ab initio approach, the total reactor antineutrino spectrum is a weighted sum of spectra resulting from all beta branches of all fission products in the reactor core. At all three facilities a systematic deviation of the number of observed events from the number of predicted events was noticed, i.e. approximately 6% of the predicted neutrinos were not observed. This discrepancy was named the reactor neutrino anomaly. In theoretical studies it is assumed that all the decays are allowed in shape, but a quarter of all transitions are actually forbidden and may have a complex energy dependence that will affect the total reactor antineutrino spectrum. In order to estimate the effect of forbidden transitions, we perform a fully self-consistent calculation of spectra from all contributing transitions and compare the results with a purely allowed approximation.

antineutrino, reactor

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