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Dijet Resonance Search with Weak Supervision Using √s=13  TeV pp Collisions in the ATLAS Detector

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Published
Article number131801
<mark>Journal publication date</mark>21/09/2020
<mark>Journal</mark>Phys Rev Lett
Issue number13
Volume125
Number of pages23
Publication StatusPublished
<mark>Original language</mark>English

Abstract

This Letter describes a search for narrowly resonant new physics using a machine-learning anomaly detection procedure that does not rely on signal simulations for developing the analysis selection. Weakly supervised learning is used to train classifiers directly on data to enhance potential signals. The targeted topology is dijet events and the features used for machine learning are the masses of the two jets. The resulting analysis is essentially a three-dimensional search A→BC, for mAO(TeV), mB,mCO(100  GeV) and B, C are reconstructed as large-radius jets, without paying a penalty associated with a large trials factor in the scan of the masses of the two jets. The full run 2 √s=13  TeV pp collision dataset of 139  fb-1 recorded by the ATLAS detector at the Large Hadron Collider is used for the search. There is no significant evidence of a localized excess in the dijet invariant mass spectrum between 1.8 and 8.2 TeV. Cross-section limits for narrow-width A, B, and C particles vary with mA, mB, and mC. For example, when mA=3  TeV and mB≳200  GeV, a production cross section between 1 and 5 fb is excluded at 95% confidence level, depending on mC. For certain masses, these limits are up to 10 times more sensitive than those obtained by the inclusive dijet search. These results are complementary to the dedicated searches for the case that B and C are standard model bosons.