Physics / Fizik
Permanent URI for this collectionhttps://hdl.handle.net/11147/6
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Article Citation - WoS: 7Citation - Scopus: 8Search for Gauge Extensions of the Mssm at the Lhc(American Physical Society, 2009) Ahmed, Ali; Demir, Durmuş Ali; Frank, Mariana; Turan, İsmailThe extensions of the minimal supersymmetric model (MSSM), driving mainly from the need to solve the μ problem, involve novel matter species and gauge groups. These extended MSSM models can be searched for at the LHC via the effects of the gauge and Higgs bosons or their fermionic partners. Traditionally, the focus has been on the study of the extra forces induced by the new gauge and Higgs bosons present in such models. An alternative way of studying such effects is through the superpartners of matter species and the gauge forces. We thus consider a U(1)′ gauge extension of the MSSM, and perform an extensive study of the signatures of the model through the production and decays of the scalar quarks and gluino, which are expected to be produced copiously at the LHC. After a detailed study of the distinctive features of such models with regard to the signatures at the LHC, we carry out a detailed Monte-Carlo analysis of the signals from the process pp→nleptons+mjets+E T, and compare the resulting distributions with those predicted by the MSSM. Our results show that the searches for the extra gauge interactions in the supersymmetric framework can proceed not only through the forces mediated by the gauge and Higgs bosons but also through the superpartner forces mediated by the gauge and Higgs fermions. Analysis of the events induced by the squark/gluino decays presented here is complementary to the direct Z′ searches at the LHC.Article Citation - WoS: 2Citation - Scopus: 2Muon Anomalous Magnetic Moment Constraints on Supersymmetric U(1)?? Models(American Physical Society, 2010) Cincioğlu, Elif; Kırca, Zerrin; Sert, Hale; Solmaz, Saime; Solmaz, Levent; Hiçyılmaz, YaşarWe study the anomalous magnetic moment of the muon in supersymmetric E 6 models and generic U(1)′ models to probe the model reactions and to find constraints on the large parameter space of these models. For future searches, by imposing the existing bounds coming from collider searches and theoretical considerations upon the U(1)′ model parameters, we examine the lightest Higgs boson mass mh and the mass of the additional Z boson mZ2 in such singlet extensions of the MSSM. We observed that not only supersymmetric E6 models but also generic U(1)′ models are sensitive to the imposition of the considered bounds. Indeed, without the muon anomaly constraints E6 models and generic U(1)′ models can predict mh as large as ∼150GeV and ∼180GeV, respectively. However, in addition to the mentioned constraints when a 1σ range for the anomalous magnetic moment of the muon is considered, we observe that generic U(1)′ models do not favor the mass of the lightest Higgs boson to be larger than 140 GeV; it should be smaller than 135 GeV in E6 models. © 2010 The American Physical SocietyArticle Citation - WoS: 14Citation - Scopus: 15Cern Lep Indications for Two Light Higgs Bosons and the U(1)' Model(American Physical Society, 2006) Demir, Durmuş Ali; Solmaz, Levent; Solmaz, SaimeReanalyses of LEP data have shown preference to two light CP-even Higgs bosons. We discuss implications of such a Higgs boson spectrum for the minimal supersymmetric model extended by a standard model singlet chiral superfield and an additional Abelian gauge invariance [the U(1)′ model]. We, in particular, determine parameter regions that lead to two light CP-even Higgs bosons while satisfying existing bounds on the mass and mixings of the extra vector boson. In these parameter regions, the pseudoscalar Higgs is found to be nearly degenerate in mass with either the lightest or next-to-lightest Higgs boson. Certain parameters of the U(1)′ model such as the effective μ parameter are found to be significantly bounded by the LEP two light Higgs signal.Article Citation - WoS: 10Citation - Scopus: 12Neutralino Dark Matter in the Left-Right Supersymmetric Model(American Physical Society, 2006) Demir, Durmuş Ali; Frank, Mariana; Turan, İsmailWe study the neutralino sector of the left-right supersymmetric model. In addition to the possibilities available in the minimal supersymmetric model, the neutralino states can be superpartners of the U(1)B-L gauge boson, the neutral SU(2)R gauge boson, or of the Higgs triplets. We analyze neutralino masses and determine the parameter regions for which the lightest neutralino can be one of the new pure states. We then calculate the relic density of the dark matter for each of these states and impose the constraints coming from the ρ parameter, the anomalous magnetic moment of the muon, b→sγ, as well as general supersymmetric mass bounds. The lightest neutralino can be the bino, or the right-wino, or the neutral triplet Higgsino, all of which have different couplings to the standard model particles from the usual neutralinos. A light bino satisfies all the experimental constraints and would be the preferred dark matter candidate for light supersymmetric scalar masses, while the right-wino would be favored by intermediate supersymmetric mass scales. The neutral triplet Higgs fermion satisfies the experimental bounds only in a small region of the parameter space, for intermediate to heavy supersymmetric scalar masses.