Erlangen 2026 – scientific programme

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T: Fachverband Teilchenphysik

T 48: Methods in Particle Physics III

T 48.6: Talk

Wednesday, March 18, 2026, 17:30–17:45, KH 00.020

Calibration of the Photon Identification Efficiency in ATLAS — •Leonor Santos Pereira Trigo — Deutsches Elektronen-Synchrotron (DESY), Zeuthen, Germany

The accurate measurement of photon efficiency remains an essential ingredient of many physics analyses at the LHC and with the ATLAS detector. Considering the reliance of said analyses on simulation samples, the calculation of scale factors quantifying the differences in how accurately the ATLAS detector identifies real photons and fake photons between simulation and real data is an important task. One of the methods used to obtain these scale factors is the matrix method, which provides a data-driven estimate for the efficiency of the ATLAS detector in distinguishing photons of interest from other particles misidentified as photons. With the use of data regions enriched in either true or misidentified photons, it is possible to estimate the photon identification efficiency within ATLAS with minimal reliance on background simulation.

Keywords: ATLAS; Photons; Efficiency; Calibration; Identification