Karlsruhe 2024 – scientific programme

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T: Fachverband Teilchenphysik

T 55: Methods in particle physics 4 (HCAL, jets)

T 55.5: Talk

Wednesday, March 6, 2024, 17:00–17:15, Geb. 20.30: 2.066

Measurement of single charged pion energy response of the ATLAS calorimeter from W^±→ τ^±(→ π^±ν_τ) ν_τ events in LHC Run 2 and Run 3 — •Anubhav Gupta and Chris Malena Delitzsch — TU Dortmund Germany

Jets are collimated sprays of charged and neutral hadrons (or their decay products) resulting from energetic proton-proton collisions. In the ATLAS experiment, the energy of these particles is measured in calorimeters, while the momentum of charged particles is determined by the tracking system. To reconstruct jets, a particle-flow algorithm combines the information from both systems. The calibration of the jet energy scale relies heavily on the accurate simulation of hadron interactions with the calorimeter. Hence, gaining a better understanding of the calorimeter’s energy response is essential. A powerful method to achieve this is by analyzing the ratio of the energy (E) of hadrons reconstructed in the calorimeter to the momentum (p) measured in the well-aligned tracking system. Charged pions from τ-decays provide a sample of high-p_T isolated particles to probe the higher energy regime where the in-situ measurements (at jet level) run out of statistics. A E/p measurement was performed using single charged pions events from τ-decays for Run 2 in a previous ATLAS software release. The detector simulation, using GEANT4, has been tuned on the results from this E/p measurement for LHC Run 3. In the talk, E/p measurement using single charged pions events from τ-decays for LHC Run 2 in current software release and for LHC Run 3 is presented.

Keywords: calorimeter energy response; E/p; jet energy scale; jet