Browsing by Author "Solmaz, Levent"

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Charged higgs boson in MSSM and beyond
(Amer Phyical Soc, 2018-06-27) Hıçyılmaz, Yaşar; Selbuz, Levent; Solmaz, Levent; Ün, Cem Salih; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0002-0595-8803; N-3421-2014; 55325758100
We conduct a numerical study over the constrained MSSM (CMSSM), next-to-MSSM (NMSSM) and U(1) extended MSSM (UMSSM) to probe the allowed mass ranges of the charged Higgs boson and its dominant decay patterns, which might come into prominence in the near future collider experiments. We present results obtained from a limited scan for CMSSM as a basis and compare its predictions with the extended models. We observe within our data that a wide mass range is allowed as 0.5(1) less than or similar to m(H)(+/-) less than or similar to 17 TeV in UMSSM (NMSSM). We find that the dominant decay channel is mostly (H-+/- -> tb) such that BR(H-+/- -> tb) similar to 80%. While this mode remains dominant over the whole allowed parameter space of CMSSM, we realize some special domains in the NMSSM and UMSSM, in which BR(H-+/- -> tb) less than or similar to 10%. In this context, the decay patterns of the charged Higgs can play a significant role to distinguish among the SUSY models. In addition to the tb decay mode, we find that the narrow mass scale in CMSSM allows only the decay modes for the charged Higgs boson to tau nu (similar to 16%), and their supersymmetric partners (tau) over tilde(nu) over tilde (similar to 13%). On the other hand, it is possible to realize the mode in NMSSM and UMSSM in which the charged Higgs boson decays into a chargino and neutralino pair up to about 25%. This decay mode requires nonuniversal boundary conditions within the MSSM framework to be available, since CMSSM yields BR(H-+/- -> (chi) over tilde (1)(0)<(chi(+/-)(1))over tilde>) less than or similar to. 1%. It can also be probed in the near future collider experiments through the missing energy and CP-violation measurements. Moreover, the chargino mass is realized as m((chi) over tilde1)(+/-) TeV in NMSSM and UMSSM, and these solutions will be likely tested soon in collider experiments through the chargino-neutralino production. Focusing on the chargino-neutralino decay patterns, we also present tables which list the possible ranges for the charged Higgs production and decay modes.
Generalized soft breaking leverage for the MSSM
(Amer Physical, 2015-05-29) Tanyıldızı, Sukru Hanif; Kerman, Saime; Solmaz, Levent; Un, Cem Salih; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0002-0595-8803; N-3421-2014; 55325758100
In this work we study implications of additional nonholomorphic soft breaking terms (mu', A(t)', A(b)', and A(t)') on the minimal supersymmetric extension of the standard model (MSSM) phenomenology. By respecting the existing bounds on the mass measurements and restrictions coming from certain B-decays, we probe reactions of the MSSM to these additional soft breaking terms. We provide examples in which some slightly excluded solutions of the MSSM can be made to be consistent with the current experimental results. During this, even after applying additional fine-tuning constraints, the nonholomorphic terms are allowed to be as large as hundreds of GeV. Such terms prove that they are capable of enriching the phenomenology and varying the mass spectra of the MSSM heavily, with a reasonable amount of finetuning. We observe that Higgsinos, the lightest stop, the heavy Higgs boson states A; H; H-+/-, sbottom and stau exhibit the highest sensitivity to the new terms. We also show how the light stop can become nearly degenerate with top quark using these nonholomorphic terms.
Least fine-tuned U(1) extended SSM
(Elsevier, 2018-05-30) Hiçyılmaz, Yaşar; Solmaz, Levent; Tanyıldızı, Şükrü Hanif; Ün, Cem Salih; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0002-0595-8803; N-3421-2014; 55325758100
We consider the Higgs boson mass in a class of the UMSSM models in which the MSSM gauge group is extended by an additional U(1)' group. Implementing the universal boundary condition at the GUT scale we target phenomenologically interesting regions of UMSSM where the necessary radiative contributions to the lightest CP-even Higgs boson mass are significantly small and LSP is always the lightest neutralino. We find that the smallest amount of radiative contributions to the Higgs boson mass is about 50 GeV in UMSSM, this result is much lower than that obtained in the MSSM framework, which is around 90 GeV. Additionally, we examine the Higgs boson properties in these models in order to check whether if it can behave similar to the SM Higgs boson under the current experimental constraints. We find that enforcement of smaller radiative contribution mostly restricts the U(1)' breaking scale as v(S) less than or similar to 10 TeV. Besides, such low contributions demand h(S) similar to 0.2-0.45. Because of the model dependency in realizing these radiative contributions theta(E6) < 0 are more favored, if one seeks for the solutions consistent with the current dark matter constraints. As to the mass spectrum, we find that stop and stau can be degenerated with the LSP neutralino in the range from 300 GeV to 700 GeV; however, the dark matter constraints restrict this scale as m(<(t)over tilde>), m((tau) over tilde) greater than or similar to 500 GeV. Such degenerate solutions also predict stop-neutralino and stau-neutralino co-annihilation channels, which are effective to reduce the relic abundance of neutralino down to the ranges consistent with the current dark matter observations. Finally, we discuss the effects of heavy M-Z' in the fine-tuning. Even though the radiative contributions are significantly low, the required fine-tuning can still be large. We comment about reinterpretation of the fine-tuning measure in the UMSSM framework, which can yield efficiently low results for the fine-tuning the electroweak scale.
Muon anomalous magnetic moment constraints on supersymmetric U(1)⊃′ models
(Amer Physical, 2010-09-10) Cincioğlu, Elif; Sert, Hale; Solmaz, Saime; Solmaz, Levent; Hiçyılmaz, Yaşar; Kırca, Zerrin; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; AAH-8661-2021; 6508185203
We 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 m(h) and the mass of the additional Z boson m(Z2) in such singlet extensions of the MSSM. We observed that not only supersymmetric E-6 models but also generic U(1)' models are sensitive to the imposition of the considered bounds. Indeed, without the muon anomaly constraints E-6 models and generic U(1)' models can predict m(h) as large as similar to 150 GeV and similar to 180 GeV, respectively. However, in addition to the mentioned constraints when a 1 sigma 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 E-6 models.
Quasi-Yukawa unification and fine-tuning in U(1) extended SSM
(Amer Physical, 2016-11-02) Hiçyılmaz, Yaşar; Ceylan, Meltem; Altaş, Aslı; Solmaz, Levent; Ün, Cem Salih; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 0000-0002-0595-8803; N-3421-2014; 55325758100
We consider the low scale implications in the U(1)' extended minimal supersymmetric Standard Model (UMSSM). We restrict the parameter space such that the lightest supersymmetric particle (LSP) is always the lightest neutralino. In addition, we impose quasi-Yukawa unification (QYU) at the grand unification scale (M-GUT). QYU strictly requires the ratios among the Yukawa couplings as y(t)/y(b) similar to 1.2, y(tau)/y(b) similar to 1.4, and y(t)/y(tau) similar to 0.8. We find that the need for fine-tuning over the fundamental parameter space of QYU is in the acceptable range (Delta(EW) <= 10(3)), even if the universal boundary conditions are imposed at M-GUT, in contrast to CMSSM and nonuniversal Higgs masses. The UMSSM with universal boundary conditions yields heavy stops (m((t) over tilde) greater than or similar to 2.5 TeV), gluinos (m((g) over tilde) greater than or similar to 2 TeV), and squarks from the first two families (m((q) over tilde) greater than or similar to 4 TeV). Similarly, the stau mass is bounded from below at about 1.5 TeV. Despite this heavy spectrum, we find Delta(EW) greater than or similar to 300, which is much lower than that needed for the minimal supersymmetric models. In addition, the UMSSM yields a relatively small mu term, and the LSP neutralino is mostly formed by the Higgsinos of mass. greater than or similar to 700 GeV. We also obtain bino-like dark matter of mass about 400 GeV. The wino is usually found to be heavier than Higgsinos and binos, but there is a small region where mu similar to M-1 similar to M-2 similar to 1 TeV. We also identify a chargino-neutralino coannihilation channel and A-resonance solutions which reduce the relic abundance of LSP neutralinos down to the ranges compatible with the current WMAP and Planck measurements.