Determination of the misreconstruction rate of hadron jets as hadronically decaying $\tau$ leptons using $q\bar{q} \to jets + Z (\to ee)$ events with ATLAS

This study will focus on a very specific issue of the hadronically decaying t lepton reconstruction at the Large Hadron Collider (LHC) with the A Toroidal Large Hadron Collider ApparatuS (ATLAS) detector. Since hadronised quarks (”jets”) have quite a similar particle spectrum in the final state, it is not always possible to distinguish between both signatures in the detector. Therefore, this study presents a way to estimate the rate at which QCD jets are misreconstructed as t candidates in QCD dijet events by determining a parameterised misreconstruction rate in $Z (\to ee) + jets$ events. In addition, the method is verified using a top quark pair event sample, which shows the performance of this analysis and its application on the t fake rate estimation in event samples with different compositions of quark and gluon initialized jets. The results presented in this study are mainly driven by simulations representing an integrated luminosity of 30 pb$^{-1}$. They also include an outlook on the application to data recorded by ATLAS the used luminosity for data is $L = 15pb^{-1}$. The study is the completion of another study which used the same method only determining the identification fake rate (reconstruction to identification level) of QCD dijet events. This two step analysis is driven by the similar two step reconstruction / identification process at ATLAS.