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ÜN, CEM SALİH

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FEN-EDEBİYAT FAKÜLTESİ

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CEM SALİH

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Muon g-2, neutralino dark matter and stau nlsp
(Springer, 2022-06-25) Gomez, Mario E.; Shafi, Qaisar; Ün, Cem Salih; ÜN, CEM SALİH; Tiwari, Amit; Fen Edebiyat Fakültesi; Fizik Bölümü; 0009-0004-0685-4389; 0000-0002-0595-8803; N-3421-2014
We explore the implications of resolving the muon g - 2 anomaly in a SU(4)(c) x SU(2)(L) x SU(2)(R) model, where the soft supersymmetry breaking scalar and gaugino masses break the left-right (LR) symmetry. A 2 sigma resolution of the anomaly requires relatively light sleptons, chargino and LSP neutralino. The stau turns out to be the NLSP of mass m(tau) less than or similar to 400 GeV, and the sleptons from the first two families can be as heavy as about 800 GeV. The chargino is also required to be lighter than about 600 GeV to accommodate the muon g - 2 solutions consistent with the dark matter relic density constraint. The dominant right-handed nature of the light slepton states suppress the sensitivity of possible signals which can be probed in Run3 experiments at the LHC. We also discuss the impact of accommodating the Higgs boson mass and the vacuum stability of the scalar potential for these solutions. Although a light stau can be compatible with the stability of the scalar potential, the Higgs boson mass constraint has a strong impact on the solutions with tan beta bounded from above, namely tan beta less than or similar to 20. The Higgsinos are heavier than about 4 TeV, and the LSP neutralino has the correct relic density if it is Bino-like. We identify stau-neutralino coannihilation as the dominant mechanism for realizing the desired dark matter relic density, with sneutrino-neutralino coannihiliation playing a minor role. These bino-like dark matter solutions can yield a spin-independent scattering cross-section on the order of 10(-13) pb which hopefully, can be expected to be tested in the near future.
B - Yukawa unification in SUSY SU(5) with mirage mediation: LHC and dark matter implications
(Springer, 2019-05-08) Raza, Shabbar; Shafi, Qaisar; Ün, Cem Salih; ÜN, CEM SALİH; Fen Edebiyat Fakültesi; Fizik Bölümü; 0000-0002-0595-8803; N-3421-2014
We consider a class of b - Yukawa unified Supersymmetric (SUSY) SU(5) GUTs, in which the asymptotic gaugino M-1,M-2,M-3 masses are generated through the mirage mediated supersymmetry breaking, which is a combination of the gravity and anomaly mediation. Due to the contributions from the anomaly contribution, M-3 is always lighter than M-1 and M-2, and consequently for the range of asymptotic masses considered, the gluino mass mg at low scale is bounded from above at about 4 TeV. We realize two different regions, in one of which the MSSM -term is less than about 3 TeV. This region yields a stop mass up to 5 TeV, and the stop mass is nearly degenerate with the LSP neutralino for mass around 0.8 to 1.7 TeV. A stau mass can be realized up to about 5 TeV, and the stau mass is approximately degenerate with the LSP neutralino for mass around 2 to 3 TeV. In addition, an A-funnel solution with mA approximate to 2m approximate to 700-900 GeV is realized. These three cases yield LSP dark matter abundance in accordance with observations. A second region, on the other hand, arises for 10. The -term is rather large (20 TeV), and the LSP neutralino is a bino-wino mixture. The gluino mass (approximate to 0.8-1.2 TeV) is nearly degenerate with the LSP neutralino mass and hence, the gluino-neutralino coannihilation processes play a role in reducing the relic abundance of LSP neutralino down to ranges allowed by the current WMAP measurements. The two regions above can be distinguished through the direct detection experiments. The first region with relatively low values yields Higgsino-like DM, whose scattering on the nucleus typically has a large cross-section. We find that such solutions are still allowed by the current results from the LUX experiment, and they will be severely tested by the LUX-Zeplin (LZ) experiment. The second region contains bino-wino DM whose scattering cross-section is relatively low. These solutions are harder to rule out in the foreseeable future.
Monophoton events with light Higgs bosons in the secluded UMSSM
(Amer Physical Soc, 2023-10-03) Hiçyılmaz, Yaşar; Selbuz, Levent; Ün, Cem Salih; ÜN, CEM SALİH; Fen Edebiyat Fakültesi; Fizik Bölümü; 0000-0002-0595-8803 ; N-3421-2014
We explore the Higgs boson implications of a class of supersymmetric models, which extends the MSSM gauge group by a U(1)' symmetry, which is broken at low energy scales by vacuum expectation values of four MSSM singlet fields. These singlets also form a secluded sector, and one of them is allowed to interact with the MSSM Higgs fields directly. After the U(1)' and electroweak symmetry breaking, the low scale spectra include six CP -even and four CP-odd Higgs bosons, whose masses can lie from 80 GeV to 2-3 TeV. We find that the heavy CP-even Higgs bosons can be probed through their decays into a pair of SM gauge bosons currently up to about m(hi) similar or equal to 1.5 TeV, while their probe can be extended to about mh(i) similar or equal to 2.5 TeV in the near future. The most interesting feature of the low scale spectra in the class of secluded U(1)' models is to include two light CP -odd Higgs bosons whose masses are bounded at about 250 GeV by the current collider and DM experiments, when the LSP neutralino is mostly formed by the MSSM singlets. These light CP -odd Higgs bosons should be formed by the MSSM singlet scalars to be consistent with the current constraints. Despite their singlet nature, they can be traced through their associated production with photons. In our work, we consider their productions at the collider experiments together with photons, and we realize that these light Higgs bosons can potentially be probed during Run-3 experiments of LHC when they are lighter than about 100 GeV. We also show that Run-4 and HL-LHC experiments will be able to probe these light scalars up to about 250 GeV.
Electron and muon magnetic moments and implications for dark matter and model characterisation in non-universal U(1)′ supersymmetric models
(Springer, 2021-09-16) Frank, Mariana; Hiçyılmaz, Yaşar; Mondal, Subhadeep; Özdal, Özer; Ün, Cem Salih; ÜN, CEM SALİH; Fen Edebiyat Fakültesi; Fizik Bölümü; 0000-0002-0595-8803; N-3421-2014
We attribute deviations of the muon and electron magnetic moments from the theoretical predictions to the presence of an additional U(1)' supersymmetric model. We interpret the discrepancies between the muon and electron anomalous magnetic moments to be due to the presence of non-universal U(1)' charges. In a minimally extended model, we show that requiring both deviations to be satisfied imposes constraints on the spectrum of the model, in particular on dark matter candidates and slepton masses and ordering. Choosing three benchmarks with distinct dark matter features, we study implications of the model at colliders, concentrating on variables that can distinguish our non-universal scenario from other U(1)' implementations.
Model characterization and dark matter in the secluded U(1)' model
(Amer Physical Soc, 2022-03-29) Hiçyilmaz, Yaşar; Selbuz, Levent; Solmaz, Levent; Ün, Cem Salih; ÜN, CEM SALİH; Fen Edebiyat Fakültesi; Fizik Ana Bilim Dalı; 0000-0002-0595-8803; N-3421-2014
We consider a class of U(1)'-extended minimal supersymmetric extension of the Standard Model (MSSM) in which the U(1)' symmetry is broken by vacuum expectation values of four MSSM singlet fields. While one MSSM singlet field interacts with the MSSM Higgs fields, three of them interact only with each other in forming a secluded sector. Assigning universal U(1)' charges for three families, the anomaly cancellation condition requires exotic fields which are assumed to be heavy and decoupled. We discuss a variety of U(1)' charge assignments and anomaly cancellation, Z'/Z hierarchy, neutralinos, charginos and the Higgs sector. We find that the typical spectra involve two CP-odd Higgs bosons lighter than about 200 GeV and 600 GeV respectively, which are mostly formed by the MSSM singlet fields. If the relic density of dark matter is saturated only by a neutralino, compatible solutions predict LSP neutralinos formed by the MSSM singlet fields in the mass scales below about 600 GeV, while it is possible to realize MSSM neutralino LSP above these mass scales. One can classify the implications in three scenarios. Scenario I involves NLSP charginos, while Scenario II involves charginos which do not participate coannihilation processes with the LSP neutralino. These two scenarios predict MSSM singlet LSP neutralinos, while Scenario I leads to larger scattering cross sections of dark matter. Scenario III has the solutions in which the MSSM neutralinos are considerably involved in LSP decomposition which yields very large scattering cross section excluded by the direct detection experiments.
Proton lifetime in minimal SUSY SU(5) in light of LHC results
(Springer, 2022-02-21) Babu, K. S.; Gogoladze, Ilia; Ün, Cem Salih; ÜN, CEM SALİH; Fen Edebiyat Fakültesi; Fizik Bölümü; 0000-0002-0595-8803; N-3421-2014
We examine proton decay mediated by color-triplet Higgsinos in minimal supersymmetric SU(5) grand unified theory in light of the discovery of the Higgs boson and the absence of SUSY signals at the LHC. We pay special attention to various threshold effects arising from Planck-suppressed operators that affect the color-triplet Higgsino mass and also allow for correcting the wrong mass relations for the light fermions. Our analysis allows for a non-universal SUSY spectrum with the third family sfermions having a separate mass compared to the first two families. We identify the allowed parameter space of the model and show that the SUSY scalar masses are constrained by current limits from proton lifetime to be above 5 TeV, while the glunio, Wino and the Higgsinos may be within reach of the LHC. When the SUSY scalar masses are required to be <= 30 TeV, so that they are within reach of next generation collider experiments, we find that proton lifetime for the decay p -> (nu) over barK(+) is bounded by tau(p -> (nu) over barK(+)) <= 1.1 x 10(35) yrs.
Sparticle spectroscopy and dark matter in a U(1) B-L extension of MSSM
(Springer, 2021-01-26) Ahmed, Waqas; Raza, Shabbar; Shafi, Qaisar; Ün, Cem Salih; Zhu, Bin; ÜN, CEM SALİH; Fen Edebiyat Fakültesi; Fizik Bölümü; 0000-0002-0595-8803; N-3421-2014
We consider a class of SUSY models in which the MSSM gauge group is supplemented with a gauged U(1)(B-L) symmetry and a global U(1)(R) symmetry. This extension introduces only electrically neutral states, and the new SUSY partners effectively double the number of states in the neutralino sector that now includes a blino (from B - L) and singlino from a gauge singlet superfield. If the DM density is saturated by a LSP neutralino, the model yields quite a rich phenomenology depending on the DM composition. The LSP relic density constraint provides a lower bound on the stop and gluino masses of about 3 TeV and 4 TeV respectively, which is testable in the near future collider experiments such as HL-LHC. The chargino mass lies between 0.24 TeV and about 2.0 TeV, which can be tested based on the allowed decay channels. We also find m tau1 greater than or similar to 500 GeV, and me,m mu,mvS,P greater than or similar to 1 TeV. We identify chargino-neutralino coannihilation processes in the mass region 0.24 TeV less than or similar to m chi 10approximate to mchi 1+/- less than or similar to 1.5 TeV, and also coannihilation processes involving stau, selectron, smuon and sneutrinos for masses around 1 TeV. In addition, A(2) resonance solutions are found around 1 TeV, and H-2 and H-3 resonance solutions are also shown around 0.5 TeV and 1 TeV . Some of the A(2) resonance solutions with tan beta greater than or similar to 20 may be tested by the A/H -> tau (+)tau (-) LHC searches.. While the relic density constraint excludes the bino-like DM, it is still possible to realize higgsino, singlino and blino-like DM for various mass scales. We show that all these solutions will be tested in future direct detection experiments such as LUX-Zeplin and Xenon-nT.
Prospects for sneutrino dark matter in the blssm
(Soc Italiana Fisica, 2018-07-01) King, Simon J. D.; Delle Rose, Luigi; Khalil, Shaaban; Kulkarni, Suchita; Marzo, Carlo; Moretti, Stefano; Ün, Cem Salih; ÜN, CEM SALİH; Fen Edebiyat Fakültesi; Fizik Ana Bilim Dalı; N-3421-2014
The (B - L) Supersymmetric Standard Model (BLSSM) motivates several Dark Matter (DM) candidates beyond the Minimally Supersymmetric Standard Model (MSSM). We assess the comparative naturalness of the two models and discuss the potential detection properties of a particular candidate, the Right-Handed (RH) sneutrino.
Explaining the R(D) and R(D*) anomalies in the B-L supersymmetric standard model with inverse seesaw mechanism
(Amer Physical Soc, 2023-04-19) Boubaa, Dris; Khalil, Shaaban; Moretti, Stefano; Ün, Cem Salih; ÜN, CEM SALİH; Fen Edebiyat Fakültesi; Fizik Bölümü; 0000-0002-0595-8803; N-3421-2014
We investigate the R(D) and R(D*) anomalies in the context of the B - L extension of the minimal supersymmetric Standard Model with inverse seesaw. We demonstrate that the lepton penguin W +/- l nu over bar l (l = e, mu,tau) mediated by CP-even/odd right-handed sneutrinos, charginos, and neutralinos can account for these anomalies simultaneously.
Associated production of charged higgs boson and heavy top quark in the left-right twin higgs model at high energye-e+ collider
(Amer Inst Physics, 2019-01-01) Mishonov, TM; Varonov, AM; Kırca, Zerrin; KIRCA, ZERRİN; Altın, Zafer; Ün, Cem Salih; ÜN, CEM SALİH; Fen Edebiyat Fakültesi; Fizik Bölümü; Mishonov, TM; Varonov, AM; 0000-0002-0595-8803; N-3421-2014; AAH-8661-2021
The left-right twin Higgs (LRTH) model is a concrete realization of the twin Higgs mechanism, which predicts the existence of a new heavy top quark (T) and charged Higgs boson (phi(+/-)). Detecting of these new particles in the LRTH model depends on free parameters (f, (f) over cap, M) which are constrained by the electroweak precision measurments. We study the associated production of a charged Higgs boson (phi(+)) and a heavy top quark (T) via e(-)e(+) -> phi(+)(T) over barb in the framework the LRTH model at root s=3000 GeV and yearly integrated luminosity of L=500 fb(-1). We find that the production cross section of the process e(-)e(+)-> phi(+)(T) over barb can reach to the level of several tens fb and a statical significance of 5 sigma can be achieved in the suitable parameter space of the LRTH model at root s=3000 GeV.