arXiv subjects

Ali Cici

Publications and source records attributed to Ali Cici.

7 recordsLinked to original sources

arXiv2026

Mono-Z' Signatures in the B-L Supersymmetric Standard Model at the LHC

The B-L Supersymmetric Standard Model with Inverse Seesaw (BLSSM-IS) extends the Minimal Supersymmetric Standard Model (MSSM) by incorporating a gauged B-L symmetry, right-handed neutrinos and an additional neutral gauge boson Z'. Searches at the Large Hadron Collider (LHC) constrain the mass of this gauge boson to be as low as only ~ 2.2 TeV in the BLSSM-IS, owing to interference effects with the SM. In this framework, mono-Z' events can arise from the associated production of a Z' boson and a singlet Higgs boson h', where h' subsequently decays into missing energy carried by a pair of the Lightest Supersymmetric Particle (LSP) - either a neutralino or a right-handed sneutrino - which serves as a Dark Matter (DM) candidate. Focusing on leptonic decays of the Z' (electrons and muons), we analyse the kinematic distributions of the final-state leptons and the missing transverse energy in order to extract a signal for this process which is independent of the nature of the BLSSM-IS DM.

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arXiv2026

Compressed Stop-Neutralino Spectra from Yukawa Unified Non-Holomorphic Pati-Salam Model: Prospects for the FCC

We explore the weak-scale phenomenology of SUSY models with the $SU(4)_{C}\times SU(2)_{L}\times SU(2)_{R}$ gauge symmetry. We include non-holomorphic soft supersymmetry breaking terms arising from perturbations on D-branes. These terms significantly alter the implications of Yukawa unification, as they directly interfere in the threshold corrections to the Yukawa couplings. With these corrections, Yukawa unification can be compatible with low fine-tuning alongside a heavy Higgsino-like lightest supersymmetric particle; however, these solutions are strongly constrained by dark matter observations. Furthermore, in contrast to previous studies, the non-holomorphic contributions accommodate heavy gluino masses in this class of models from approximately 2.2 to 10 TeV while preserving Yukawa unification. These gluinos can be probed up to about 2.5 TeV in high-luminosity collider searches, and up to about 6 TeV at future 100 TeV center-of-mass energy colliders. With the non-holomorphic threshold corrections to Yukawa couplings, Yukawa unification can be accommodated with relatively light third-generation squarks. We find that the supersymmetric spectra can accommodate sbottom masses around 1.5 TeV, making them highly accessible to upcoming experimental searches. The stop can also be as light as about 1.5~TeV, resulting in a compressed stop-neutralino spectrum. Although these solutions lie beyond the sensitivity of current collider searches, they can be potentially probed at future facilities, such as the proposed Future Circular Collider. Our results do not include systematic uncertainties, which can heavily impact the experimental analysis. In this context, our findings serve to highlight potential directions and prospects for new physics searches at future collider experiments. Our results assume that overall systematic uncertainties in background modeling do not exceed $0.1\%$.

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arXiv2024

Resolving the W-Boson Mass in the Lepton Specific Two Higgs Doublet Model

In 2022, the CDF Collaboration reported the $W$-boson mass, $M_W=80.4335\pm0.0094~\mathrm{GeV}$, which deviates from the Standard Model (SM) prediction, $M_W^{\rm SM}=80.357\pm0.006~\mathrm{GeV}$, by about $7\sigma$. By contrast, the CMS Collaboration obtained $M_W=80.3602\pm0.0099~\mathrm{GeV}$, very close to the SM global electroweak fit value of $\sim80.357~\mathrm{GeV}$. Motivated by this situation, we reassess the $W$-boson mass within the Lepton-Specific Two Higgs Doublet Model (LS-2HDM). We perform random scans (generated with SARAH 4.13.0 and evaluated with SPheno 4.0.3) and confront the results with up-to-date theoretical and experimental constraints. In the LS-2HDM, if $h_1$ is the SM-like Higgs at $m_{h_1}\simeq125$ GeV with $|\cos(\beta-\alpha)|\lesssim0.06$, $17\lesssim\tan\beta\lesssim39$, $144\lesssim m_{h_2}\lesssim414$ GeV, and $435\lesssim m_{A,H^{\pm}}\lesssim685$ GeV, the model reproduces the 2024 CMS $W$-boson mass within $3\sigma$. Solutions near the 2022 CDF value, $M_W=80.4335\pm0.0094~\mathrm{GeV}$, survive; however, after applying all constraints, including HiggsTools, they approach it at best within $\lesssim2\sigma$. Our findings emphasize that the LS-2HDM favors the CMS results consistently with the current experimental results. On the other hand, while one can accommodate also the CDF results in this model theoretically, up-to-date electroweak precision bounds on the oblique parameters $(S,T,U)$ together with the SM-like Higgs and LFU constraints exclude these solutions and our results for $W-$boson mass can be only as close as about $2\sigma$ to the CDF results.

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arXiv2022

The 28 GeV Dimuon Excess in Lepton Specific 2HDM

We explore the Higgs mass spectrum in a class of Two Higgs Doublet Models (THDMs) in which a scalar SU(2)_L doublet interacts only with quarks, while the second one interacts only with leptons. The spectrum includes two CP-even Higgs bosons, either of which can account for the SM-like Higgs boson, and the spectra involving light Higgs bosons receive strong impacts from the LEP results and the current collider analyses. We find that a consistent spectrum can involve a CP-odd Higgs boson as light as about 10 GeV, while the lightest CP-even Higgs boson cannot be lighter than about 55 GeV when m_A ~ 28 GeV. These analyses can rather bound the low tan beta region which can also accommodate an observed excess in dimuon events at m_mumu ~ 28 GeV. A lepton-specific class of THDMs (LS-THDM) can predict such an excess through A -> mu mu decays, while the solutions can be constrained by the A -> tau tau mode. After constraining the solutions with the consistent ranges of sigma(pp -> bbA -> bb tau tau), a largest excess at about 1.5 sigma at 8 TeV center of mass (COM) energy and 2 sigma at 13 TeV COM is observed for tan beta ~ 12 and m_A ~ 28 GeV in the sigma(pp -> bbA -> bb mu mu) events.

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arXiv2019

Gluino Search with Stop and Top in Nonuniversal Gaugino Mass Models at LHC and Future Colliders

We discuss the gluino mass in the CMSSM and Nonuniversal Gaugino Mass Models (NUGM) frameworks in light of the results from the current LHC and Dark Matter experiments. We probe the gluino mass scales by considering its decay modes into stop and top quarks, $\tilde{g}\rightarrow \tilde{t}_{1}t$ and $\tilde{g}\rightarrow \bar{t}t\tildeχ_{1}^{0}$, where $\tilde{t}_{1}t$ represents both $\tilde{t}_{1}\bar{t}$ and $\tilde{t}_{1}^{*}t$. The region with $m_{\tilde{g}} \lesssim 2$ TeV is excluded up to $68\%$ CL in the CMSSM if the gluino decays into a stop and top quark, while the $95\%$ CL exclusion requires $m_{\tilde{g}}\gtrsim 1.9$ TeV. Such exclusion bounds on the gluino mass more or less overlap with the current LHC results. The decay mode $\tilde{g}\rightarrow \bar{t}t\tildeχ_{1}^{0}$ may take over if $\tilde{g}\rightarrow \tilde{t}_{1}t$ is not allowed. One can probe the gluino mass in this case up to about 1.5 TeV with $68\%$ CL in the CMSSM, and about 1.4 TeV with $95\%$ CL. A similar analyses in the NUGM framework yield exclusion curves for the gluino mass $m_{\tilde{g}}\gtrsim 2.1$ TeV at 14 TeV for both decay modes of the gluino under consideration. We also show that increasing the center of mass energy to 27 TeV can probe the gluino mass up to about 3 TeV through its decay mode into stop and top quark. The Dark Matter constraints are not very severe in the framework of NUGM, and they allow solutions with $m_{\tilde{g}},m_{\tilde{t}} \gtrsim 1$ TeV. In addition, with NUGM the LSP neutralino can coannihilate with gluino and/or stop for $m_{\tilde{g}},m_{\tilde{t}}\approx m_{\tildeχ_{1}^{0}} \in [0.9-1.5]$ TeV. The 100 TeV FCC collider can probe the gluino masses up to about 6 TeV with $36.1~fb^{-1}$ integrated luminosity. We also find that the decay $\tilde{g}\rightarrow \tilde{t}t$ can indirectly probe the stop mass up to about 4 TeV.

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arXiv2017

Light Stops and Fine-Tuning in MSSM

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 scalem and explore the low scale implications. We realize that the fine-tuning parametrized with Delta_EW can be as low as zero. We consider the stop mass with a special importance and focus on the mass scales as m_stop <=700 GeV, which are excluded by current experiments when the stop decays into a neutralino along with a top quark or a chargino along with a b quark. We find that the stop mass can be as low as about 200 GeV with Delta_EW ~ 50. We find that the solutions in this region can be exluded only up to 60% when stop decays into a neutralino-top quark, and 50% when it decays into a chargino-b quark pair. Setting 65% CL to be potential exclusion and 95% to be pure exclusion limit such solutions will be tested in near future experiments, which are conducted with higher luminosity. In addition to stop, the region with low fine-tuning and light stops predicts masses for the other supersymmetric particles such as m_sbottom >~ 600 GeV, m_stau >~ 1 TeV, m_chargino >~ 120 GeV. The details for the mass scales and decay rates are also provided by tables of benchmark points.

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arXiv2017

Just a Scalar in THDM

We review the THDM model in which one of the Higgs doublets does not develop a vacuum expectation value. In this case, the Higgs fields with zero VEV does not contribute to the physical masses of the SM particles, and hence, its interactions with the SM particles can have more freedom than in the case of usual considerations on the THDM models. We show that the stability of the Higgs potential minima can be maintained. All the Higgs boson masses are found lighter than about 300 GeV in the low scale spectrum when v_1=0. Such light mass scales are in the detectable regime, and hence, the SM predictions and the experimental results are essential to be applied in the analyses. Especially the decay channels; h-->W^+ W^- and h-->bb exclude most of the solutions, while it is still possible to realize a small region, which coincides with the SM predictions. We highlight that it is also possible to realize an excess in h--> gamma gamma decay channel, even one applies the constraints from the Higgs boson decays into W^+ W^- and bb. In addition, if one assumes H is the SM-like Higgs boson of mass about 125 GeV, the solutions with m_h <~ 125 GeV can be acceptable. In this case, the solutions can still be realized consistent with the SM predictions; however, an excess in H --> gamma gamma cannot be observed, while the implications for this channel in THDM can stay in the SM prediction rates at most. Even though the light masses of the Higgs bosons can be favored in resolution to discrepancy between the Standard Model and the experiment in the muon anomalous magnetic moment measurements, we find that it is not possible to accommodate such a resolution with BR(b --> s gamma) results simultaneously.

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