Dortmund 2021 – scientific programme

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T: Fachverband Teilchenphysik

T 90: Muon detectors

T 90.5: Talk

Thursday, March 18, 2021, 17:05–17:20, To

Muon reconstruction efficiency evaluation with the ATLAS detector at the LHC using J/ψ and Υ resonances — •Noemi Cavalli — INFN and Università di Bologna, Italy - TU Dortmund, Germany

This work is carried out within the Muon Combined Performance group of the ATLAS Experiment at the LHC. Muon reconstruction efficiencies are measured using data collected by the detector. J/ψ —→ µ µ events are employed and the "Tag and Probe method" is used. The ratio between the reconstruction efficiency obtained from the data and from simulated J/ψ samples is then evaluated. This ratio is called "Scale Factor" and it is provided to the ATLAS Collaboration to correct simulated muon samples employed in physics analyses. In particular, the Scale Factor systematic uncertainty associated to the fit model choice has been improved by using Monte Carlo samples with real background events injected on the simulated samples to test the fit performance.

In the second part of the work the reconstruction efficiency and Scale Factor evaluation has been extended to Υ —→ µ µ events. The Υ resonance has never been exploited by the ATLAS Collaboration to get muon reconstruction efficiencies and its implementation would be complementary to the other standard candles used so far. A dedicated strategy for Υ events has been developed, starting from the one employed for the J/ψ meson. The state of the art and the outlook on future developments is presented.