Unit:
Department of PhysicsLibrary of the School of Science
Author:
Papavergou Ioanna
Dissertation committee:
Κωνσταντίνος Βελλίδης, Αναπληρωτής Καθηγητής Τμήμα Φυσικής, ΕΚΠΑ,
Παρασκευάς Σφήκας, Καθηγητής Τμήμα Φυσικής, ΕΚΠΑ
Γεώργιος Διαμάτης, Αναπληρωτής Καθηγητής Τμήμα Φυσικής, ΕΚΠΑ
Νικόλαος Τετράδης, Καθηγητής Τμήμα Φυσικής , ΕΚΠΑ
Δημήτριος Φασουλιώτης, Καθηγητής Τμήμα Φυσικής, ΕΚΠΑ
Κωνσταντίνος Κουσουρής, Αναπληρωτής Καθηγητής τομέα Φυσικής ΣΕΜΦΕ, ΕΜΠ
Cristina Botta, Assistant professor, Physics Department, University of Zurich
Original Title:
A search for Supersymmetry in the compressed mass spectrum in events with three soft leptons and missing transverse momentum with the CMS experiment at the LHC.
Translated title:
A search for Supersymmetry in the compressed mass spectrum in events with three soft leptons and missing transverse momentum with the CMS experiment at the LHC.
Summary:
Thε dissertation presents a search for Supersymmetry (SUSY) in models with compressed mass spectrum of the
supersymmetric particles, which predict observable final states containing Standard Model (SM) particles of low
transverse momentum and missing transverse energy (MET). The analysis focuses on final states with two or three
leptons (electrons or muons), which have an overall lower background from SM processes comparing with
hadronic final states predicted by these models. The main background in the examined leptonic final states
originates from lepton misidentification, when either the lepton is not genuine (a hadron misidentified as a lepton)
or it does not come from the primary interaction vertex where supersymmetric particles can be produced. Advanced
techniques of estimating this background are applied in the dissertation, then the contributions are estimated from
all SM processes producing the final states under consideration, and the estimates are compared with the
experimental data based on the distributions of selected kinematic variables which are sensitive to supersymmetric
particle decays. No contribution from such decays is observed in the comparison, therefore exclusion limits on the
supersymmetric particle masses of the examined models are extracted using statistical inference.
Main subject category:
Science
Keywords:
SUSY, compressed mass spectra, leptonic final states, CMS, LHC
Number of references:
206
