arXiv subjects

Mohammed Boukidi

Publications and source records attributed to Mohammed Boukidi.

At least 19 recordsLinked to original sources

arXiv2026

Can $\gamma\gamma$ collisions rival $e^-e^+$ in probing doubly charged Higgs bosons?

High-energy $\gamma\gamma$ collisions, realizable as an operational mode of future lepton linear colliders such as the ILC and CLIC, provide a promising environment to probe extended Higgs sectors. We investigate the sensitivity of such colliders to doubly charged Higgs bosons within the 2-Higgs Doublet Model with type-II seesaw (2HDMcT). Focusing on the three-body production channels $\gamma\gamma \to H^{\pm\pm}H_1^{\mp}H_1^{\mp}$ and $\gamma\gamma \to H^{\pm\pm}H_1^{\mp}W^{\mp}$, we perform a parameter space scan consistent with theoretical constraints as well as current collider, flavor, and electroweak precision observables (EWPOs). We show that $\gamma\gamma$ collisions can rival the discovery potential of the conventional $e^+e^-$ mode for probing doubly charged Higgs bosons through a $4\ell+E_T^{miss}$ signature ($\ell=e,\mu$). Despite the reduced effective luminosity resulting from the photon spectrum, the significantly enhanced production cross sections, exceeding those in electron-positron collisions by more than one order of magnitude, compensate for this limitation. By performing a detailed signal-to-background analysis at center-of-mass energies of $\sqrt{s}=830$ and $1245$ GeV, we demonstrate that a discovery significance at the $5\sigma$ level can be achieved for viable benchmark points (BPs).

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arXiv2026

Impact of hidden heavy Higgs channels of VLB-Quarks below 1 TeV in 2HDM

We investigate the phenomenological impact of incorporating vector-like bottom (VLB) quarks into the Type-II Two-Higgs-Doublet Model (2HDM-II). This framework introduces novel beyond-Standard-Model (BSM) decay channels $B \to Hb$, $B \to Ab$, and $B \to H^-t$, which are typically ignored by LHC pair-production searches focused on Standard Model (SM) final states ($B \to Zb$, $B \to hb$, $B \to Wt$). Our analysis reveals that these BSM pathways significantly weaken current VLB mass constraints. In the 2HDM-II alignment limit, the mass limit for a singlet $B$ shifts from approximately 1.5 TeV down to 1.34 TeV. For $(T, B)$ and $(B, Y)$ doublet configurations, the mass limits relax further to approximately 0.98 TeV, driven by the dominance of $B \to Hb$ and $B \to Ab$ decays, which can reach combined branching ratios of nearly 100\%.

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arXiv2026

Probing Heavy Neutral Higgs Bosons via Single Vector-Like Bottom Quark Production at the HL-LHC

We investigate the discovery prospects of a singly produced vector-like bottom quark in the Type-II Two-Higgs-Doublet Model extended by an $SU(2)_L$ vector-like $(T,B)$ doublet. We focus on the non-standard decay chain $B \to \phi b$, followed by $\phi \to t\bar{t}$, where $\phi = H$ or $A$, leading to a final state with one charged lepton, missing transverse energy, and multiple $b$-jets. We perform a full simulation of both signal and Standard Model backgrounds at $\sqrt{s}=14$ TeV. We show that the exotic channels $B \to \phi b$ can dominate over the conventional decay modes, reaching branching ratios of order $50\%$ for both neutral scalars in the alignment limit. A conventional cut-based analysis provides a $5\sigma$ discovery significance only at sufficiently high integrated luminosity. By contrast, an XGBoost-based multivariate analysis substantially improves the signal-background discrimination and extends the discovery reach up to $m_B \simeq 1.3$ TeV with $600~\mathrm{fb}^{-1}$ and up to $m_B \simeq 1.6$ TeV with $3~\mathrm{ab}^{-1}$, even in the presence of systematic uncertainties as large as $15\%$.

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arXiv2026

Probing Doubly Charged Higgs Bosons with Three-Body Associated Production at Future $e^+e^-$ Colliders

We study the discovery prospects for a doubly charged Higgs boson $H^{\pm\pm}$ in the 2-Higgs doublet model with type-II seesaw at future $e^+e^-$ colliders. Focusing on the three-body channels $e^+e^- \to H^{\pm\pm}H_1^{\mp}H_1^{\mp}$ and $e^+e^- \to H^{\pm\pm}H_1^{\mp}W^{\mp}$, we scan the model parameter space subject to theoretical consistency as well as current collider, flavor and electroWeak precision observables (EWPOs). We find that these $2\to3$ production modes can exceed the conventional pair-production rate $e^+e^- \to H^{++}H^{--}$, followed by $H^{\pm\pm}\to H_1^{\pm}H_1^{\pm}$ and $H^{\pm}_1W^{\pm}$ decays, over wide regions, particularly above the $H^{\pm\pm}\to H_1^{\pm}H_1^{\pm}$ and $H^{\pm\pm}\to H_1^{\pm}W^{\pm}$ thresholds, reaching cross sections up to ${\cal O}(10^2)$~fb for $\sqrt{s}=500$--$1500$~GeV. A detector-level analysis of the $4\ell + E_T^{\text{miss}}$ signature, including dominant multiboson and top quark backgrounds, shows that discovery sensitivity is achievable for $\sqrt{s}=1000$-$1500$~GeV with integrated luminosities in the few ab$^{-1}$ range, even in the presence of realistic systematic uncertainties.

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arXiv2025

Interpreting the 650 GeV and 95 GeV Higgs anomalies in the next-to-two-Higgs-doublet model

Recent experimental hints from the Large Hadron Collider (LHC) in di-photon and partially in the $\tau^+\tau^-$ final states suggest the possible existence of an additional Higgs boson with a mass around 95 GeV. Interestingly, these observations are consistent with earlier results from the Large Electron-Positron (LEP) collider, which pointed to an excess in $b\bar b$ final states within a similar mass range. Additionally, CMS has observed an excess in the $\gamma\gamma b\bar{b}$ final state, indicating a possible resonance near 650 GeV decaying into a pair of SM-like Higgs bosons or into a SM-like Higgs boson accompanied by a lighter scalar with mass near 95 GeV. In this work, we investigate whether these anomalies can be simultaneously explained within the Next-to-2-Higgs-Doublet Model (N2HDM), an extension of the Standard Model (SM) scalar sector featuring two complex Higgs doublets and an additional real singlet. Assuming the existence of a CP-even Higgs state compatible with the 95 GeV excesses (restricted to the $\gamma\gamma$ and $b\bar b$ channels). Our results show that a heavy CP-even Higgs resonance around 650 GeV, produced predominantly via gluon-gluon fusion and subsequently decaying into a 125 GeV Higgs boson together with another scalar at approximately 95 GeV, can be simultaneously accommodated within both the N2HDM Type-II and Type-Y frameworks in parameter regions that remain consistent with the relevant experimental $2\sigma$ intervals for the reported excesses, once all theoretical and experimental constraints are imposed. This interpretation leads to distinctive and testable predictions for the ongoing LHC Run~3 and the forthcoming High-Luminosity LHC (HL-LHC) phase, in particular through correlated rates in the $\gamma\gamma b\bar b$, $\tau^+\tau^- b\bar b$, $b\bar b\,\gamma\gamma$, and $\gamma\gamma\tau^+\tau^-$ final states.

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arXiv2025

Exploring Potential Higgs Resonances at 650 GeV and 95 GeV in the 2HDM Type III

Recent searches by the CMS collaboration at the Large Hadron Collider (LHC) in the `diphoton plus $b\bar{b}$ final state' have revealed an excess near 650 GeV, which might indicate the presence of a (broad) heavy resonance decaying into a Standard Model (SM) Higgs boson and an additional particle. At the same time, both ATLAS and CMS as well as all experiments at the Large Electron-Position (LEP) collider have reported excesses consistent with a light Higgs boson channel around 95 GeV, suggesting a potential connection between these two signals. In this study, we investigate these anomalies within the context of the CP-conserving 2-Higgs-Doublet Model (2HDM) Type~III. In our proposed scenario, a heavy CP-odd Higgs boson $A$ with a mass near 650 GeV decays into a SM-like Higgs boson $H$ and a $Z$ boson, with the $H$ boson subsequently decaying into diphotons and the $Z$ boson decaying into $b\bar{b}$ pairs. To explain the excess around 95 GeV, we independently select the mass of the light CP-even Higgs boson of the model $h$ to be around this value. This configuration allows for a consistent explanation of both the high- and low-mass excesses observed in the experiments. Through a detailed analysis, we demonstrate that these two signals can be fitted simultaneously at the 2.5$\sigma$ significance level, offering a promising solution to the observed anomalies and potentially hinting at new physics Beyond the Standard Model (BSM).

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arXiv2024

Vector-Like Quarks at the LHC: A Unified Perspective from ATLAS and CMS Exclusion Limits

In this work, we present a comprehensive review of the most up-to-date exclusion limits on Vector-Like Quarks (VLQs) derived from ATLAS and CMS data at the Large Hadron Collider (LHC). Our analysis encompasses both pair and single production modes, systematically comparing results from the two collaborations to identify and employ the most stringent bounds at each mass point. We evaluate the excluded parameter space for VLQs under singlet, doublet, and triplet representations. For top-like VLQs ($T$), the exclusion limits rule out masses up to 1.49 TeV in singlet scenarios, while single production constrains the mixing parameter $\kappa$ to values below 0.26 at $m_T \sim 1.5$ TeV and up to 0.42 for $m_T \sim 2$ TeV. For bottom-like VLQs ($B$), the strongest exclusion limits from pair production exclude masses up to 1.52 TeV in doublet configurations, with single production constraining $\kappa$ values between 0.2 and 0.7 depending on the mass. For exotic VLQs, such as $X$ and $Y$, pair production excludes masses up to 1.46 TeV and 1.7 TeV, respectively. The constraints on $\kappa$ from these analyses become increasingly restrictive at higher masses, reflecting the enhanced sensitivity of single production channels in this regime. For $X$, $\kappa$ is constrained below 0.16 for masses between 0.8 and 1.6 TeV and further tightens to $\kappa < 0.2$ as the mass approaches 1.8 TeV. Similarly, for $Y$, $\kappa$ values are constrained below 0.26 around $m_Y \sim 1.7$ TeV, with exclusions gradually relaxing at higher masses. These exclusion regions, derived from the most stringent LHC search results, offer a unified and up-to-date perspective on VLQ phenomenology. The results were computed using \texttt{VLQBounds}, a new Python-based tool specifically developed for this purpose.

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arXiv2024

Large Hadron Collider Signatures of Exotic Vector-Like Quarks within the 2-Higgs Doublet Model Type-II

We study the decay of the exotic Vector-Like Quarks (VLQs) $X$ and $Y$, with $5/3$ and $-4/3$ units of electric charge, respectively, within the 2-Higgs Doublet Model (2HDM). Building on our previous studies of Vector-Like Top and Bottom (VLT and VLB) quarks, we now investigate the characteristics of $X$ and $Y$ in the alignment limit of a Type-II Yukawa structure and show that, in the framework of such a 2HDM, one can have large non-Standard Model (SM) decay rates of the $X$ and$ Y$ states. Our analysis focuses on their potential detection at the Large Hadron Collider (LHC), based on their pair production followed by a variety of both SM and non-SM decay patterns. In order to distinguish between doublet and triplet representations of the VLQs $X$ and $Y$, we uncover specific signatures that can provide insights into this particular architecture of Beyond the SM (BSM) physics.

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arXiv2024

Charged Higgs Boson Mass Bounds in 2HDM-II: Impact of Vector-Like Quarks

We explore the phenomenology of charged Higgs bosons ($H^\pm$) and Vector-Like Quarks (VLQs), specifically the top-like $T$, within the Two Higgs Doublet Model Type-II (2HDM-II). We consider both a singlet VLQ $(T)$ and a doublet $(TB)$ scenario, demonstrating that the presence of VLQs influences the scalar sector, particularly by alleviating the stringent mass constraints on $H^\pm$ imposed by $B$-physics observables such as $B\to X_s\gamma$. This relaxation arises from modifications in the couplings between $H^\pm$ and Standard Model (SM) quarks, with the magnitude of the effect differing between the singlet and doublet cases. We further analyse the constraints from the oblique parameters $S$ and $T$ on VLQ mixing angles.

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arXiv2024

Investigation of Charged Higgs Bosons Production from Vector-Like $T$ Quark Decays at $e\gamma$ Collider

Within the extended framework of the Two-Higgs-Doublet Model Type II (2HDM-II), enhanced by a vector-like quark (VLQ) doublet $TB$, we present a comprehensive analysis of the process $e^{-}\gamma \rightarrow b\nu_{e}\bar{T}$ at future high-energy $e\gamma$ colliders, focusing on the decays $\bar{T} \rightarrow H^{-} \bar{b}$ and $H^{-} \rightarrow \bar{t}b$. Using current theoretical and experimental constraints, we calculate production cross sections for both unpolarized and polarized beams at center-of-mass energies of $\sqrt{s} = 2$ and 3 TeV, demonstrating that polarized beams significantly enhance detection prospects by increasing production rates. By analyzing kinematic distributions, we establish optimized selection criteria to effectively separate signal events from background. At $\sqrt{s} = 2$ TeV with an integrated luminosity of 1500 fb$^{-1}$, we find exclusion regions within $s_R^d\in[0.085,0.16]$ for $m_T\in [1000,1260]$ GeV and a discovery potential within $s_R^d\in[0.14,0.17]$ for $m_T\in[1000,1100]$ GeV, with these regions expanding to $s_R^d\in [0.05,0.15]$ for $m_T\in[1000,1340]$ GeV and $s_R^d \in [0.11, 0.17]$ for $m_T\in[1000,1160]$ GeV at 3000 fb$^{-1}$. At $\sqrt{s} = 3$ TeV and 1500 fb$^{-1}$, we identify exclusion regions of $s_R^d\in[0.055,0.135]$ for $m_T \in [1000, 1640]$ GeV and discovery regions of $s_R^d \in [0.09, 0.15]$ for $m_T \in [1000, 1400]$ GeV, which further expand to $s_R^d \in [0.028, 0.12]$ for $m_T\in[1000,1970]$ GeV and $s_R^d \in[0.04,0.122]$ for $m_T\in[1000,1760]$ GeV at 3000 fb$^{-1}$. Our findings emphasize the increased detection potential at higher center-of-mass energies, particularly at 3 TeV compared to 2 TeV, with notable improvements when polarized beams are utilized. We also account for the effects of initial state radiation, beamstrahlung, and systematic uncertainties, which influence both exclusion and discovery prospects.

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arXiv2024

Search for charged Higgs bosons through vector-like top quark pair production at the LHC

We investigate the discovery prospects for a vector-like top partner (VLT) in the Type-II Two-Higgs-Doublet Model (2HDM-II) extended by a vector-like quark doublet ($TB$) at the 14~TeV LHC. The study focuses on the pair production process $pp \to T\bar{T} \to bH^+\, \bar{b}H^- \to b(tb)\, \bar{b}(\bar{t}b)$, yielding fully hadronic final states characterized by high $b$-jet multiplicity. Two analysis strategies are employed, requiring at least four or five $b$-tagged jets (4$b$ and 5$b$), to exploit the signal topology. Assuming a charged Higgs mass of $m_{H^\pm} \sim 600$~GeV and a systematic uncertainty of $\delta = 5\%$, the 4$b$ channel enables discovery up to $m_T \sim 1200$~GeV at $\mathcal{L} = 300~\text{fb}^{-1}$, while the 5$b$ analysis extends the reach to $m_T \sim 1300$~GeV. At higher luminosities of 1000--3000~fb$^{-1}$, the 5$b$ strategy achieves discovery sensitivity up to $m_T \sim 1400$~GeV. The reach is significantly reduced as $m_{H^\pm}$ increases, due to the suppression of the $\text{BR}(T \to H^+ b)$: for $m_{H^\pm} \sim 1000$~GeV, discovery becomes unattainable across all luminosity and systematic uncertainty configurations. Sensitivity is also strongly impacted by systematic uncertainties: for $\delta = 10\%$ and $m_{H^\pm} < 1000$~GeV, discovery remains viable up to $m_T \sim 1200$~GeV in the 5$b$ analysis, while for $\delta = 20\%$, no discovery is achievable for $m_T \geq 1000$~GeV.

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arXiv2024

Superposition of CP-Even and CP-Odd Higgs Resonances: Explaining the 95 GeV Excesses within a Two-Higgs Doublet Model

We propose an explanation for the observed excesses around 95 GeV in the di-photon and di-tau invariant mass distributions, as reported by the CMS collaboration at the Large Hadron Collider (LHC). These findings are complemented by a long-standing discrepancy in the $b\bar{b}$ invariant mass at the Large Electron-Positron (LEP) Collider. Additionally, the ATLAS collaboration has reported a corroborative excess in the di-photon final state within the same mass range, albeit with slightly lower significance. Our approach involves the superposition of CP-even and CP-odd Higgs bosons within the Type-III Two-Higgs Doublet Model (2HDM) to simultaneously explain these excesses at 1$\sigma$ Confidence Level (C.L.), while remaining consistent with current theoretical and experimental constraints.

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arXiv2024

Anatomy of Vector-Like Bottom-Quark Models in the Alignment Limit of the 2-Higgs Doublet Model Type-II

Expanding upon our ongoing investigation of Vector-Like Quark (VLQ) phenomenology within a 2-Higgs Doublet Model (2HDM) framework, in this paper, we complement a previous one dedicated to Vector-Like Top-quarks (VLTs) by studying Vector-Like Bottom-quarks (VLBs), specifically focusing on their behavior in the alignment limit of a Type-II Yukawa structure. We examine the potential for detecting VLBs at the Large Hadron Collider (LHC) and analyze their decay signatures, encompassing both Standard Model (SM) processes and exotic decays. The objective is to differentiate among singlet, doublet, and triplet configurations of VLBs by identifying distinct decay patterns, thereby providing insights into the structure of Beyond the SM (BSM) physics.

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arXiv2024

Anatomy of Vector-Like Top-Quark Models in the Alignment Limit of the 2-Higgs Doublet Model Type-II

A comprehensive extension of the ordinary 2-Higgs Doublet Model (2HDM), supplemented by Vector-Like Quarks (VLQs), in the "alignment limit" is presented. In such a scenario, we study the possibility that Large Hadron Collider (LHC) searches for VLQs can profile their nature too, i.e., whether they belong to a singlet, doublet, or triplet representation. To achieve this, we exploit both Standard Model (SM) decays of VLQs with top-(anti)quark Electromagnetic (EM) charge ($T$), i.e., into $b,t$ quarks and $W^\pm, Z,h$ bosons (which turn out to be suppressed and hence $T$ states can escape existing limits) as well as their exotic decays, i.e., into $b,t$ (and possibly $B$) quarks and $H^\pm, H, A$ bosons. We show that quite specific decay patterns emerge in the different VLQ representations so that, depending upon which $T$ signals are accessed at the LHC, one may be able to ascertain the underlying Beyond Standard Model (BSM) structure, especially if mass knowledge of the new fermionic and bosonic sectors can be inferred from (other) data.

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arXiv2023

Explanation of the Hints for a 95 GeV Higgs Boson within a 2-Higgs Doublet Model

We suggest an explanation for and explore the consequences of the excess around 95 GeV in the di-photon and di-tau invariant mass distributions recently reported by the CMS collaboration at the Large Hadron Collider (LHC), together with the discrepancy that has long been observed at the Large Electron-Positron (LEP) collider in the $b\bar b$ invariant mass. Interestingly, the most recent findings announced by the ATLAS collaboration do not contradict, or even support, these intriguing observations. Their search in the di-photon final state similarly reveals an excess of events within the same mass range, albeit with a bit lower significance, thereby corroborating and somewhat reinforcing the observations made by CMS. We demonstrate that the lightest CP-even Higgs boson in the general 2-Higgs Doublet Model (2HDM) Type-III can explain simultaneously the observed excesses at approximately 1.3 $\sigma$ C.L. while satisfying up-to-date theoretical and experimental constraints. Moreover, the 2HDM Type-III predicts an excess in the $pp\to t\bar t H_{\rm SM}$ production channel of the 125 GeV Higgs boson, $H_{\rm SM}$. This effect is caused by a up to 12\% enhancement of the $H_{\rm SM}tt$ Yukawa coupling in comparison to that predicted by the Standard Model. Such an effect can be tested at the High Luminosity LHC (HL-LHC), which can either discover or exclude the scenario we suggest. This unique characteristic of the 2HDM Type-III makes this scenario with the 95 GeV resonance very attractive for further theoretical and experimental investigations at the (HL-)LHC and future colliders.

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arXiv2023

The oblique parameters in the 2HDM with Vector-Like Quarks: Confronting $M_W$ CDF-II Anomaly

The CDF collaboration has released a new measurement of the $W$ boson mass using their complete data set with 8.8 fb$^{-1}$ in $p\bar{p}$ collisions. This result deviates from the Standard Model prediction by around 7$\sigma$. We explain how the two Higgs doublet model (2HDM) with vector-like quarks is affected by the recently discovered W boson mass. In our study, we include both theoretical constraints such as perturbative unitarity and vacuum stability as well as a number of experimental constraints. We also look into how the effective mixing angle, measured by the SLD collaboration in addition to the CDF W-boson mass, is used to determine the $S$ and $T$ parameters. In the alignment limit, we investigate the case where the lighter CP-even neutral Higgs boson of the 2HDM is the one found at the LHC and demonstrate how the parameter space of the 2HDM type II in the presence of vector-like quarks is constrained. It is found that in most cases, there is a cancellation between the 2HDM and vector-like quarks contributions, which enlarges the parameter space of both models.

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arXiv2022

Probing a 96 GeV Higgs Boson in the Di-Photon Channel at the LHC

Recently the CMS collaboration reported a $\sim 3 \sigma$ local excess in the di-photon spectrum at 96 GeV. The same mass range concurs with a $\sim2 \sigma$ local excess in the $b\bar{b}$ invariant mass spectrum in four-jet events collected at LEP. In this contribution we show that at 1$\sigma$ level the 2HDM type-III can perfectly fit both excesses simultaneously, while satisfying all experimental and theoretical constraints.

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arXiv2022

Identifying light charged Higgs boson in the $\mu\nu$ channel in 2HDM Type-III

In this contribution, we discuss the light charged Higgs boson production via $pp \to \bar{t} bH^\pm$ at the Large Hadron Collider (LHC) in the Two-Higgs Doublet Model (2HDM) Type-III. We explore the prospect of looking the aforementioned Higgs boson production channel followed by $H^\pm\mu\nu$ signal. The latter has the potential to be overwhelmingly stronger than $H^\pm\tau\nu$ and $H^\pm c\bar{s}$ signals in Type-III. We show that in both scenarios standard and inverted hierarchy and after including several theoretical and experimental constraints, the production process $pp \to \bar{t}bH^\pm$ followed by $H^\pm\to \mu\nu$ could represent the most promising experimental option to search for light charged Higgs boson at the LHC.

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