Reconstruction efficiency measurements of low-p_T muons in Run 2 at the ATLAS detector

Soft leptons are an important signature of many promising searches for physics beyond the Standard Model and Standard Model measurements. Thus it is vital to address any mismodeling in Monte Carlo generators by comparing the reconstruction efficiencies in simulation and data. This talk presents the reconstruction efficiency measurements for low-p_T muons down to 4 GeV at the ATLAS detector from J/ψ → μμ events which are selected with the Tag and Probe method. Performing the measurements with different probe types allows for mutual validation of the results. The talk introduces the fitting procedure for computing the efficiency and the evaluation of systematic uncertainties. To reduce background contamination in particular for low-p_T probes, the tracks of the tag-and-probe pair are matched to a J/ψ vertex candidate. The influence of this matching on the systematic uncertainties is discussed.