Abstract

We have examined the impact of new Daya Bay, Double Chooz, and RENO measurements on global fits of reactor antineutrino flux data to a variety of hypotheses regarding the origin of the reactor antineutrino anomaly. In comparing RENO and Daya Bay measurements of inverse beta decay (IBD) yield versus $^{239}$Pu fission fraction, we find differing levels of precision in measurements of time-integrated yield and yield slope, but similar central values, leading to modestly enhanced isotopic IBD yield measurements in a joint fit of the two datasets. In the absence of sterile neutrino oscillations, global fits to all measurements now provide 3{\sigma} preference for incorrect modeling of specific fission isotopes over common mis-modeling of all beta-converted isotopes. If sterile neutrino oscillations are considered, global IBD yield fits provide no substantial preference between oscillation-including and oscillation-excluding hypotheses: hybrid models containing both sterile neutrino oscillations and incorrect $^{235}$U or $^{239}$Pu flux predictions are favored at only 1-2{\sigma} with respect to models where $^{235}$U, $^{238}$U, and $^{239}$Pu are assumed to be incorrectly predicted.

Highlights

  • Within the particle physics community, there remains enduring interest in the observed deficit of detected reactor antineutrino fluxes relative to the commonly used conversion predictions [1,2]

  • We show that the addition of RENO and the new absolute flux results enables some improvement in the precision of isotopic inverse beta decay (IBD) yield measurements

  • Daya Bay flux evolution datasets are similar in their preferred central values of absolute IBD yield and yield slopes, but differ in their level of precision, due to lower statistical and systematic uncertainties and wider fission fraction ranges provided by Daya Bay

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Summary

Giunti

We have examined the impact of new Daya Bay, Double Chooz, and RENO measurements on global fits of reactor antineutrino flux data to a variety of hypotheses regarding the origin of the reactor antineutrino anomaly. In the absence of sterile neutrino oscillations, global fits to all measurements provide 3σ preference for incorrect modeling of specific fission isotopes over common mismodeling of all beta-converted isotopes. If sterile neutrino oscillations are considered, global IBD yield fits provide no substantial preference between oscillation-including and oscillation-excluding hypotheses: hybrid models containing both sterile neutrino oscillations and incorrect 235U or 239Pu flux predictions are favored at only 1σ–2σ with respect to models where 235U, 238U, and 239Pu are assumed to be incorrectly predicted

INTRODUCTION
EXPERIMENTAL INPUTS
IBD YIELD FITTING PROCEDURE
COMPARISON OF RENO AND DAYA BAY RESULTS
GLOBAL FLUX FITS
Findings
SUMMARY

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