Reconstruction and identification of pairs of collimated τ-leptons decaying hadronically using √s=13 TeV pp collision data with the ATLAS detector

AbstraktAbstract

This paper describes an algorithm for reconstructing and identifying a highly collimated hadronically decaying tau-lepton pair with low transverse momentum. When two tau-leptons are highly collimated, their visible decay products might overlap, degrading the reconstruction performance for each of the tau-leptons. A dedicated treatment attempting to tag the tau-lepton pair as a single object is required. The reconstruction algorithm is based on a large radius jet and its associated two leading subjets, and the identification uses a boosted decision tree to discriminate between signatures from tau+tau- systems and those arising from QCD jets. The efficiency of the identification algorithm is measured in Z gamma events using proton-proton collision data at root s = 13 TeV collected by the ATLAS experiment at the Large Hadron Collider between 2015 and 2018, corresponding to an integrated luminosity of 139 fb(-1). The resulting data-to-simulation scale factors are close to unity with uncertainties ranging from 26 to 37%.

This paper describes an algorithm for reconstructing and identifying a highly collimated hadronically decaying tau-lepton pair with low transverse momentum. When two tau-leptons are highly collimated, their visible decay products might overlap, degrading the reconstruction performance for each of the tau-leptons. A dedicated treatment attempting to tag the tau-lepton pair as a single object is required. The reconstruction algorithm is based on a large radius jet and its associated two leading subjets, and the identification uses a boosted decision tree to discriminate between signatures from tau+tau- systems and those arising from QCD jets. The efficiency of the identification algorithm is measured in Z gamma events using proton-proton collision data at root s = 13 TeV collected by the ATLAS experiment at the Large Hadron Collider between 2015 and 2018, corresponding to an integrated luminosity of 139 fb(-1). The resulting data-to-simulation scale factors are close to unity with uncertainties ranging from 26 to 37%.