Unit:
Κατεύθυνση Πυρηνική Φυσική και Φυσική Στοιχειωδών ΣωματιδίωνLibrary of the School of Science
Author:
Plastiras Nikolaos
Supervisors info:
Βελλίδης Κωνσταντίνος, Αναπληρωτής Καθηγητής, Τμήμα Φυσικής, ΕΚΠΑ
Σφήκας Παρασκευάς, Καθηγητής, Τμήμα Φυσικής, ΕΚΠΑ
Παπαδημητρίου Ιωάννης, Αναπληρωτής Καθηγητής, Τμήμα Φυσικής, ΕΚΠΑ
Original Title:
Optimization of tt+bb background simulation in the search for c-quark Yukawa coupling through the ttH(bb/cc) process in the CMS experiment at the LHC
Translated title:
Optimization of tt+bb background simulation in the search for c-quark Yukawa coupling through the ttH(bb/cc) process in the CMS experiment at the LHC
Summary:
The study of the associated production of top and bottom quark-antiquark pairs, tt+bb, in proton-proton (pp) collisions at the LHC poses a significant challenge due to the nonnegligible mass of the b quark and the disparate energy scales characterizing interactions involving top and b quarks. Consequently, the determination of appropriate energy scales for the calculation of the tt+bb matrix element and the seamless interface of the matrix element with parton distributions and parton showers becomes a non-trivial task. Uncertainties related to the choice of renormalization and factorization scales in matrix element calculations at NLO in QCD, can lead to uncertainties of up to 50% in fiducial and differential cross section predictions of tt+bb production. Improved knowledge of this process is therefore of prime interest in order to validate or discard scale choices made for state-of-the-art simulations. The primary objective of this thesis is to optimize the simulation of tt+bb production, a pivotal background in numerous searches and measurements. Notably, tt+bb is a prominent background in the associated production of a top quark pair with a Higgs boson (ttH), where the Higgs boson decays to a pair of b or c quarks (H->bb/cc). An improved understanding of tt+bb production will help reduce the uncertainties in the process ttH(bb/cc), increasing the sensitivity of the search for c-quark Yukawa coupling, which is an important parameter of the Standard Model, being the Yukawa coupling of a second generation quark.
Main subject category:
Science
Keywords:
Higgs, LHC, CERN, CMS, Yukawa, charm, ttH, tt+bb
Number of references:
174
