Search for Neutrinoless Double-β Decay with the Complete EXO-200 Dataset

A search for neutrinoless double-beta decay (0 nu beta beta) in Xe-136 is performed with the full EXO-200 dataset using a deep neural network to discriminate between 0 nu beta beta and background events. Relative to previous analyses, the signal detection efficiency has been raised from 80.8% to 96.4 +/- 3.0%, and the energy resolution of the detector at the Q value of Xe-136 0 nu beta beta has been improved from sigma/E = 1.23% to 1.15 +/- 0.02% with the upgraded detector. Accounting for the new data, the median 90% confidence level 0 nu beta beta half-life sensitivity for this analysis is 5.0 x 10(25) yr with a total Xe-136 exposure of 234.1 kg yr. No statistically significant evidence for 0 nu beta beta is observed, leading to a lower limit on the 0 nu beta beta half-life of 3.5 x 10(25) yr at the 90% confidence level.