Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 16Citation - Scopus: 16Stop on Top: Susy Parameter Regions and Fine-Tuning Constraints(American Physical Society, 2014) Demir, Durmuş Ali; Ün, Cem SalihWe analyze minimal supersymmetric models in order to determine in what parameter regions with what amount of fine-tuning they are capable of accommodating the LHC-allowed top-stop degeneracy window. The stops must be light enough to enable Higgs naturalness yet heavy enough to induce a 125 GeV Higgs boson mass. These two constraints imply a large mass splitting. By an elaborate scan of the parameter space, we show that the stop-on-top scenario requires at least ΔCMSSM≃O(104) fine-tuning in the constrained minimal supersymmetric Standard Model (CMSSM). By relaxing the CMSSM parameter space with nonuniversal Higgs masses, we find that ΔNUHM1≃O(104). The CMSSM with a gravitino lightest supersymmetric particle works slightly better than the nonuniversal Higgs mass model. Compared to all these, the CMSSM with μ<0 and nonuniversal gauginos yields a much smaller fine-tuning Δμ,g≃O(100). Our results show that the gaugino sector can pave the road toward a more natural stop-on-top scenario.Conference Object Introduction To Higgs Sector: Theory and Phenomenology(Springer Verlag, 2008) Demir, Durmuş AliThis review is based on lectures delivered at International Summer School on High Energy Physics, in Akyaka, Mugla, Turkey, September 2006. The goal of the review is to introduce junior graduate students, having a some knowledge of field theory, to the problem of mass generation and its physical consequences. The review starts with the statements and a toy model of mass generation in Sect. 2. In Sect. 3 a model of weak interactions is constructed and its predictions are compared with experimental results obtained so far. Given in Sect. 4 is search strategies for Higgs boson, the only remnant of the mechanism that gives mass to matter, by referring to model predictions and experimental facilities. Finally, in Sect. 5, given are a summary of results plus reasons for and expectations from models which rehabilitate the minimal model constructed in Sect. 3.Article Citation - WoS: 18Citation - Scopus: 18Squark Pair Production in the Mssm With Explicit Cp Violation(American Physical Society, 2007) Alan, Ahmet T.; Cankoçak, Kerem; Demir, Durmuş AliWe analyze effects of the CP-odd soft phases in the MSSM on the pair productions of colored superpartners in pp collisions at the LHC energies. We find that, among all pair-production processes, those of the scalar quarks in the first and second generations are particularly sensitive to the CP-odd phases, more precisely, to the phases of the gluinos and neutralinos. We compute pair-production cross sections, classify various production modes according to their dependencies on the gluino and neutralino phases, perform a detailed numerical analysis to determine individual as well as total cross sections, and give a detailed discussion of 2. electric dipole moment (EDM) bounds. We find that pair productions of first and second generation squarks serve as a viable probe of the CP violation sources in the gaugino sector of the theory even if experiments cannot determine chirality, flavor and electric charge of the squarks produced.