Search for supersymmetry in jet topologies with the CMS detector

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Fen Edebiyat Fakültesi, Fizik Bölümü, Türkiye

Tezin Onay Tarihi: 2009

Öğrenci: KADİR ÖCALAN

Danışman: ALİ MURAT GÜLER

Özet:

Supersymmetry (SUSY) is the most motivated scenario beyond the Standard Model (SM) addressing the problems of the SM in an elegant way by establishing a symmetry which relates matter particles to interaction particles and vice versa. The simplest phenomenologically viable supersymmetric theory is the Minimal Supersymmetric Standard Model (MSSM) which can be accommodated to minimal Supergravity (mSuGra) theory in order to both take gravity into account and constrain its parameter space. CMS detector is one of the general purpose detectors constructed at LHC (Large Hadron Collider) which targets to search for SUSY signal. This thesis presents a search strategy for SUSY in three different fully hadronic jet topologies with the CMS detector. Di-jet, 3-jet, and 4-jet event topologies offer clear signatures for SUSY searches and the key SUSY decay modes of these jet topologies appear to be squark pair production, squark-gluino production, and gluino pair production, respectively. In these jet topologies, an important kinematical variable named alpha, α is used to separate SUSY signal test points from the SM background events including QCD, EWK (Electroweak), and invisible decay of Z boson processes. Alpha variables are found to be very useful in terms of enhancing SUSY signal while rejecting all QCD events. Discriminating power of alpha variables are shown in terms of signal-to-background and signal significance calculations and the results are found to be promising which further encourage searches for SUSY signal in jet event topologies with the early CMS data at 1 f b^{1} integrated luminosity.