Search for an anomalous excess of inclusive charged-current nu(e) interactions in the MicroBooNE experiment using Wire-Cell reconstruction

We report a search for an anomalous excess of inclusive charged-current (CC) nu(e) interactions using the Wire-Cell event reconstruction package in the MicroBooNE experiment, which is motivated by the previous observation of a low-energy excess (LEE) of electromagnetic events from the MiniBooNE experiment. With a single liquid argon time projection chamber detector, the measurements of nu(mu) CC interactions as well as pi(0) interactions are used to constrain signal and background predictions of nu(e) CC interactions. A data set collected from February 2016 to July 2018 corresponding to an exposure of 6.369 x 10(20) protons on target from the Booster Neutrino Beam at FNAL is analyzed. With x representing an overall normalization factor and referred to as the LEE strength parameter, we select 56 fully contained nu(e) CC candidates while expecting 69.6 +/- 8.0 (stat.) +/- 5.0 (sys.) and 103.8 +/- 9.0 (stat.) +/- 7.4 (sys.) candidates after constraints for the absence (eLEE(x=0)) of the median signal strength derived from the MiniBooNE observation and the presence (eLEE(x=1)) of that signal strength, respectively. Under a nested hypothesis test using both rate and shape information in all available channels, the best-fit x is determined to be 0 (eLEE(x= 0)) with a 95.5% confidence level upper limit of x at 0.502. Under a simple-vs-simple hypotheses test, the eLEE(x=1 )hypothesis is rejected at 3.75 sigma, while the eLE.E-x=0, hypothesis is shown to be consistent with the observation at 0.45 sigma. In the context of the eLEE model, the estimated 68.3% confidence interval of the nu(e) CC hypothesis to explain the LEE observed in the MiniBooNE experiment is disfavored at a significance level of more than 2.6 sigma (3.0 sigma) considering MiniBooNE's full (statistical) uncertainties.