Calibration of charm jet identification algorithms using proton-proton collision events at $\sqrt{s}=13~\mathrm{TeV}$

Many measurements at the LHC experiments require an efficient identification of heavy-flavour jets, i.e. jets originating from bottom (b) or charm (c) quarks. An overview of the algorithms used for c jet identification in the CMS experiment is given and a novel method to calibrate them is presented. The new method corrects the entire distribution expected as output when the algorithms are applied to jets of different flavours. It is based on an iterative method exploiting three distinct control regions that are enriched with either b jets, c jets or light-flavour jets. Finally, a validation of the method is performed by checking closure of the measured correction factors on the same collision data as well as by testing the method on toy datasets which emulate different miscalibration conditions. The calibrated results improve over traditional efficiency measurements and are expected to increase the sensitivity of future physics analysis by facilitating the use of the full distributions of heavy-flavour identification algorithm outputs, for example, as inputs to machine learning algorithms.