Cem Salih Un

Nonuniversal gaugino masses and muong-2

We consider two classes of supersymmetric models with nonuniversal gaugino masses at the grand unification scale MGUT in an attempt to resolve the apparent muon g-2 anomaly encountered in the Standard Model. We explore two distinct scenarios, one in which all gaugino masses have the same sign at MGUT, and a second case with opposite sign gaugino masses. The sfermion masses in both cases are assumed to be universal at MGUT. We exploit the nonuniversality among gaugino masses to realize large mass splitting between the colored and noncolored sfermions. Thus, the sleptons can have masses in the few hundred GeV range, whereas the colored sparticles turn out to be an order of magnitude or so heavier. In both models the resolution of the muon g-2 anomaly is compatible, among other things, with a 125–126 GeV Higgs boson mass and the WMAP dark matter bounds.

NLSP gluino and NLSP stop scenarios from

We present a study of b-tau Yukawa unified supersymmetric SU(4)_c x SU(2)_L x SU(2)_R model (with mu > 0), which predicts the existence of gluino - neutralino and stop - neutralino coannihilation scenarios compatible with the desired relic LSP neutralino dark matter abundance and other collider constraints. The NLSP gluino or NLSP stop masses vary between 400 GeV to ~ 1 TeV. The NLSP gluinos will be accessible at the 14 TeV LHC, while we hope that the NSLP stop solutions will be probed in future LHC searches. We also identify regions of the parameter space in which the gluino and the lighter stop are closely degenerate in mass, interchangeably playing the role of NLSP and NNLSP. We also update a previous study of t-b-tau Yukawa unification and show that NLSP gluino of mass ~ 1 TeV, with a mass difference between the gluino and neutralino of less than 80 GeV, can be realized consistent with the current collider and astrophysical constraints. We present benchmark points for b-tau and t-b-tau Yukawa unification that can be accessible at the LHC.

b-\tau

Abstract Motivated by the tension between the Higgs mass and muon g − 2 in minimal supersymmetric standard model (MSSM), we analyze the muon g − 2 in supersymmetric B − L extension of the standard model (BLSSM) with inverse seesaw mechanism. In this model, the Higgs mass receives extra important radiative corrections proportional to large neutrino Yukawa coupling. We point out that muon g − 2 also gets significant contribution, due to the constructive interferences of light neutralino effects. The light neutralinos are typically the MSSM Bino like and the supersymmetric partner of U ( 1 ) B − L gauge boson ( B ˜ ′ -ino). We show that with universal soft supersymmetry breaking terms, the muon g − 2 resides within 2σ of the measured value, namely ∼ 20 × 10 − 10 , with Higgs mass equal to 125 GeV.

Yukawa unification

We consider two classes of t-b-{tau} quasi-Yukawa unification scenarios which can arise from realistic supersymmetric SO(10) and SU(4){sub C}xSU(2){sub L}xSU(2){sub R} models. We show that these scenarios can be successfully implemented in the nonuniversal Higgs model with m{sub H{sub u}}=m{sub H{sub d}}{ne}m{sub 0} and the constrained minimal sumersymmetric model frameworks, and they yield a variety of sparticle spectra with Wilkinson Microwave Anisotropy Probe compatible neutralino dark matter. In the nonuniversal Higgs model with m{sub H{sub u}}=m{sub H{sub d}}{ne}m{sub 0}, we find bino-Higgsino dark matter as well as the stau coannihilation and A-funnel solutions. The constrained minimal sumersymmetric model case yields the stau coannihilation and A-funnel solutions. The gluino and squark masses are found to lie in the TeV range.

Muon anomalous magnetic moment in SUSY B − L model with inverse seesaw

We analyze minimal supersymmetric models in order to determine in what parameter regions with what amount of fine-tuning they are capable of accomodating 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 stop-on-top scenario requires at least Delta_CMSSM ~ O(10^4) fine-tuning in the CMSSM. By relaxing the CMSSM parameter space with nonuniversal Higgs masses, we find that Delta_NUHM1 ~ O(10^4). The CMSSM with gravitino LSP works slightly better than the NUHM1 model. Compared to all these, the CMSSM with mu<0 and nonuniversal gauginos yield a much smaller fine-tuning Delta_{mu,g} ~ O(100). Our results show that gaugino sector can pave the road towards a more natural stop-on-top scenario.

Sparticle Spectroscopy with Neutralino Dark matter from t-b-tau Quasi-Yukawa Unification

We present a class of models in the framework of gauge mediation supersymmetry breaking where the standard model is supplemented by additional U(1) symmetry which acts only on the third generation fermions. The messenger fields carry non-trivial U(1) charge and are vector-like particles under this symmetry. This leads to additional contribution to the soft supersymmetry breaking mass terms for the third generation squarks and sleptons. In this framework we show that the muon g-2 anomaly, the observed 125 GeV Higgs boson mass and the detected relic dark matter abundance (gravitino in our case) can be simultaneously accommodated. The resolution of the muon g-2 anomaly, in particular, yields the result that the first two generation squark masses, as well the gluino mass, should be <~ 2.5 TeV, which will be tested at LHC14.

Stop on top: SUSY parameter regions and fine-tuning constraints

We discuss the fine-tuning issue within the MSSM framework. Following the idea that the fine-tuning can measure effects of some missing mechanism, we impose non-universal gaugino masses at the GUT scale, and explore the low scale implications. We realize that the fine-tuning parametrized with

Light Stops and Fine-Tuning in MSSM

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