2021/06/07 by Maxx Richard Rahman, Rahman, Maxx Richard
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High-Energy Particle Collisions Research #Particle Detector Development and Performance #Particle physics theoretical and experimental studies
paper · pdf · doi:10.48550/arxiv.2106.03961
openalex publication_date 2021/06/07 · openalex created_date 2022/07/25 · openalex updated_date 2026/07/28
A search for singly produced vector-like T/Y quark is performed in\nproton-proton collision data at a centre-of-mass energy of 13 TeV\ncorresponding to an integrated luminosity of 139.1 fb-1, recorded with the\nATLAS detector at the LHC from 2015-18. The analysis focused on the hadronic\nchannel of T/Y \→ Wb decay mode. The hadronic channel is not a clean\nchannel, unlike the leptonic channel, because of the contribution coming from\nthe QCD processes, which accounts for a significant background. The modelling\nof QCD processes is challenging due to their theoretical prediction and\nexperimental challenges. Due to this, it is observed that the Monte Carlo\nsimulation of the QCD multijet is mismodelled in this analysis. In this thesis,\na data-driven method called the ABCD method is presented to estimate the QCD\nmultijet background. The method uses the background events from all the control\nregions to estimate the multijets in the signal region. However, a correlation\namong different control regions is observed, which is further accounted by\nintroducing a correlation factor. The correlation factor is calculated by\nperforming likelihood fit to the MC simulated backgrounds. Some additional\nstudies, including uncertainty estimation on the method and the performance of\nthe method with different jet collections and taggers, are also performed.\n