Quark and Gluon Tagging Calibration with the ATLAS detector

The separation of quark and gluon initiated jets(q/g jets) is crucial to enhance the reach of many new physics searches at the ATLAS experiment in the Large Hadron Collider. A tagger serving as a tool to distinguish quark and gluon jets is developed based on the Boosted Decision Tree using charged-particle track observables associated with the jet. However, quark-versus-gluon jet tagging is difficult to be calibrated due to the difficulty of the hadronization modeling. To improve the performance of the tagger, a "matrix method" is applied to extract the q/g distributions to obtain a scale factor which is a ratio between data and Monte Carlo. The data taken from 2015 to 2018 with an integrated luminosity of 139.0 fb^-1 in pp collisions at √s = 13 TeV with the ATLAS detector are used to calibrate the tagger with two control samples to select dijet and gamma+jet events, providing various gluon and quark enriched samples. In this talk, the latest results of calibration and systematic uncertainties will be presented.