This paper describes an algorithm for reconstructing and identifying a highly collimated hadronically decaying τ-lepton pair with low transverse momentum. When two τ-leptons are highly collimated, their visible decay products might overlap, degrading the reconstruction performance for each of the τ-leptons. A dedicated treatment attempting to tag the τ-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 τ+τ- systems and those arising from QCD jets. The efficiency of the identification algorithm is measured in Zγ events using proton–proton collision data at s=13 TeV collected by the ATLAS experiment at the Large Hadron Collider between 2015 and 2018, corresponding to an integrated luminosity of 139fb-1. The resulting data-to-simulation scale factors are close to unity with uncertainties ranging from 26 to 37%.

Aad, G., Aakvaag, E., Abbott, B., Abdelhameed, S., Abeling, K., Abicht, N.J., et al. (2025). Reconstruction and identification of pairs of collimated $$\tau $$-leptons decaying hadronically using $$\sqrt{s}=13$$ TeV pp collision data with the ATLAS detector. EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS, 85(5) [10.1140/epjc/s10052-025-14075-3].

Reconstruction and identification of pairs of collimated $$\tau $$-leptons decaying hadronically using $$\sqrt{s}=13$$ TeV pp collision data with the ATLAS detector

Di Micco, B.;Di Nardo, R.;Montereali, F.;Orestano, D.;
2025-01-01

Abstract

This paper describes an algorithm for reconstructing and identifying a highly collimated hadronically decaying τ-lepton pair with low transverse momentum. When two τ-leptons are highly collimated, their visible decay products might overlap, degrading the reconstruction performance for each of the τ-leptons. A dedicated treatment attempting to tag the τ-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 τ+τ- systems and those arising from QCD jets. The efficiency of the identification algorithm is measured in Zγ events using proton–proton collision data at s=13 TeV collected by the ATLAS experiment at the Large Hadron Collider between 2015 and 2018, corresponding to an integrated luminosity of 139fb-1. The resulting data-to-simulation scale factors are close to unity with uncertainties ranging from 26 to 37%.
2025
Aad, G., Aakvaag, E., Abbott, B., Abdelhameed, S., Abeling, K., Abicht, N.J., et al. (2025). Reconstruction and identification of pairs of collimated $$\tau $$-leptons decaying hadronically using $$\sqrt{s}=13$$ TeV pp collision data with the ATLAS detector. EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS, 85(5) [10.1140/epjc/s10052-025-14075-3].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11590/524888
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