arXiv subjects

Rachid Benbrik

Publications and source records attributed to Rachid Benbrik.

At least 37 records · Page 2Linked to original sources

arXiv2024

Probing Charged Higgs Bosons in the 2-Higgs Doublet Model Type-II with Vector-Like Quarks

We study the phenomenology of charged Higgs bosons ($H^\pm$) and Vector-Like Quarks (VLQs), denoted as $T$, the latter possessing a charge identical to the top quark one, within the framework of the Two Higgs Doublet Model Type-II (2HDM-II). Upon examining two scenarios, one featuring a singlet $(T)$ (2HDM-II+$(T)$) and another a doublet $(TB)$ (2HDM-II+$(TB)$), we discover that the presence of VLQs has a significant effect on the (pseudo)scalar sector of the 2HDM-II. In particular, this leads to a reduction in the strict constraint on the mass of the charged Higgs boson, which is imposed by $B$-physics observables, specifically $B\to X_sγ$. {The observed reduction stems from modifications in the charged Higgs couplings to the Standard Model (SM) top and bottom quarks}. Notably, the degree of this reduction varies distinctly between the singlet 2HDM+$(T)$ and doublet 2HDM+$(TB)$ scenarios. Additionally, our investigation extends to constraints imposed by the oblique parameters $S$ and $T$ on the VLQ mixing angles. Furthermore, to facilitate efficient exploration of the '2HDM-II+VLQ' parameter space, we present results on pair production of VLQs $T$ ($pp\to T\bar T$), followed by $T\to H^\pm b$ and $H^\pm \to tb$ decays, yielding a distinctive $2t4b$ final state. This investigation thus provides valuable insights guiding the search for extended Higgs and quark sectors at the Large Hadron Collider (LHC) at CERN.

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arXiv2024

Interpreting the $\boldsymbol{W}$-Mass and Muon $\boldsymbol{(g_μ-2)}$ Anomalies within a 2-Higgs Doublet Model

In this study, we investigate the anomalous magnetic moment of the muon $(g_μ-2)$ as reported by Fermilab (FNAL), along with the recent measurement of the $W$-boson mass by the CDF-II collaboration. Both findings show significant deviations from the predictions of the Standard Model (SM), hinting at the possibility of new physics. Our focus is on the Type III two-Higgs-doublet model (2HDM), wherein both Higgs doublets couple with all fermions, leading to the induction of flavour-changing neutral currents (FCNCs) at the tree level. Within this framework, we investigate a lepton-flavour-violating (LFV) scenario, aiming to explain both observed anomalies, while satisfying the up-to-date theoretical and experimental constraints.

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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 $\sim 3 σ$ local excess in the di-photon spectrum at 96 GeV. The same mass range concurs with a $\sim2 σ$ 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$σ$ 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 $μν$ 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 $H^\pmμν$ signal. The latter has the potential to be overwhelmingly stronger than $H^\pmτν$ 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 $H^\pm\to μν$ could represent the most promising experimental option to search for light charged Higgs boson at the LHC.

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arXiv2022

Search for charged Higgs boson in $μν$ channel within 2HDM type-III

We discus the muonic decay of light charged Higgs boson for $m_{H^\pm}\le m_t-m_b$ in the context of the generic two Higgs doublet model (2HDM) type-III. We show that for both alignment limit scenarios, the $H^\pm\toμν$ signal could be dominant and give alternative reachable signatures to those arising from top quark production and decay.

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arXiv2022

Explaining the 96 GeV Di-photon Anomaly in a Generic 2HDM Type-III

Motivated by results recently reported by the CMS Collaboration about an excess in the di-photon spectrum at about 96 GeV, especially when combined with another long-standing anomaly at the same value in the $b\bar b$ invariant mass spectrum in four-jet events collected at LEP, we show that a possible explanation to both phenomena can be found at 1$σ$ level in a generic 2-Higgs Doublet Model (2HDM) of Type-III in presence of a specific Yukawa texture, wherein Lepton Flavour Violating (LFV) (neutral) currents are induced at tree level. Bounds from Higgs data play a major role in limiting the parameter space of this scenario, yet we find solutions with $m_H = 125$ GeV and $m_h = 96$ GeV consistent with current theoretical and experimental bounds.

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arXiv2022

Charged Higgs boson production via $pp \rightarrow H^\pm bj$ at the LHC

The searches for charged Higgs bosons can be used to probe new physics at the LHC. In the current study, we concentrate on the associated production of the charged Higgs boson with the bottom quark and the jet in Two-Higgs Doublet Model (2HDM) type-I as promising mode for a light $H^\pm$, i.e. $m_{H^\pm}<m_t$. For this we consider the two situations where $h$ or $H$ is the SM-type Higgs boson discovered with a mass close to 125 GeV and investigate its bosonic decays, namely $H^{\pm} \to W^{\pm} h$ and/or $H^{\pm} \to W^{\pm} A$. The potential signals at the LHC are then discussed, under both theoretical and experimental constraints. Over a substantial region of the 2HDM type-I parameter space, a promising alternative signals that could be used for the discovery of $H^{\pm}$ states at the LHC are identified as $qbW+2b/2τ/2γ$.

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arXiv2021

New charged Higgs boson discovery channel at the LHC

The ATLAS and CMS experiments have an ambitious search program for charged Higgs bosons. The two main searches for $H^\pm$ at the LHC have traditionally been performed in the $τν$ and $t b$ decay channels, as they provide the opportunity to probe complementary regions of the Minimal SuperSymmetric Model (MSSM) parameter space. Charged Higgs bosons may decay also to light quarks, $H^\pm \to cs/cb$, which represent an additional probe for the mass range below $m_t$. In this work, we focus on $H^\pm \to μν$ as an alternative channel in the context of two Higgs doublet model type III. We explored the prospect of looking $pp\to tb H^\pm$, followed by $H^\pm\toμν$ signal at the LHC. Such a scenario appears in 2HDM type-III where couplings of the charged Higgs are enhanced to $μν$. Almost all the experimental searches rely on the production and decay of the charged Higgs are taken into account. We show that for a such scenario, the above signal is dominant for most of the parameter space, and $H^\pm \to μν$ can be an excellent complementary search. Benchmarks points are proposed for further Monte Carlo analysis.

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arXiv2021

New Light $H^\pm$ Discovery Channels at the LHC

A light charged Higgs boson has been searched for at the Large Hadron Collider (LHC) via top (anti)quark decay, i.e., $t \to b H^+$, if kinematically allowed. In this contribution, we propose new channels for light charged Higgs boson searches via the pair productions $pp\to H^\pm h/A$ and $pp\to H^+ H^-$ at the LHC in the context of the Two-Higgs Doublet Model (2HDM) Type-I. By focusing on a case where the heavy H state is the Standard Model (SM)-like one already observed, we investigate the production of the aforementioned charged Higgs bosons and their bosonic decay channels, namely, $H^\pm \to W^\pm h$ and/or $H^\pm \to W^\pm A$. We demonstrate that such production and decay channels can yield substantial alternative discovery channels for $H^\pm$ bosons at the LHC. Finally, we propose eight benchmark points (BPs) to motivate the search for such signatures.

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arXiv2021

One-loop radiative corrections to $e^+ e^-\to Zh^0/H^0A^0$ in the Inert Higgs Doublet Model

We compute the full one-loop radiative corrections (including both weak and QED corrections) for two processes $e^{+}e^{-}\to Z h^0,H^0 A^{0}$ in the Inert Higgs Doublet model (IHDM). Up to $O(α_{w})$ and $O(α_{em})$ order, we use FeynArts/FormCalc to compute the one-loop virtual corrections and Feynman Diagram Calculation (FDC) to evaluate the real emission, respectively. Being equipped with these computing tools, we investigate radiative corrections of new physics for both the degenerate and non-degenerate scenarios with three typical collision energies of future electron-positron colliders: 250 GeV, 500 GeV, and 1000GeV. By scanning the parameter space of IHDM, we identify the allowed regions which are consistent with constraints and bounds, from both theoretical and experimental sides. We find that the radiative corrections of the IHDM to $e^+ e^- \to Z h^0$ can be sizeable and are within the detection potentials of future Higgs factories. We also find that the new physics of IHDM could also be directly detected by observing the process $e^{+}e^{-}\to H^0 A^{0} $ which could have large enough production rate. We propose five benchmark points and examine their salient features which can serve as physics targets for future electron-positron colliders, such as CEPC/CLIC/FCC-ee/ILC as well as for LHC.

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arXiv2020

Signal versus Background Interference in $H^+\to t\bar b$ Signals for MSSM Benchmark Scenarios

In this paper, we investigate sizeable interference effects between a heavy charged Higgs boson signal produced via $gg\to t\bar b H^-$ (+ c.c.) followed by the decay $H^-\to b\bar t$ (+ c.c.) and the irreducible background given by $gg\to t\bar t b \bar b$ topologies at the Large Hadron Collider (LHC). We show how such effects could spoil current $H^\pm$ searches where signal and background are normally treated separately. The reason for this is that a heavy charged Higgs boson can have a large total width, in turn enabling such interferences, altogether leading to very significant alterations, both at the inclusive and exclusive level, of the yield induced by the signal alone. This therefore implies that currently established LHC searches for such wide charged Higgs bosons require modifications. We show such effects quantitatively using two different benchmark configurations of the minimal realisation of Supersymmetry, wherein such $H^\pm$ states naturally exist.

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arXiv2020

Mapping $pp\to A\to ZH\to l^+l^-b\bar b$ and $pp\to H\to ZA\to l^+l^-b\bar b$ Current and Future Searches onto 2HDM Parameter Spaces

By borrowing the results from a Large Hadron Collider (LHC) analysis performed with $36.1~\text{fb}^{-1}$ of Run 2 data intended to search for $A$ production followed by $ZH$ decay in turn yielding $l^+l^-b\bar b$ ($l=e,μ$) final states in the context of the standard four Yukawa types of the 2-Higgs Doublet Model (2HDM), we recast it in terms of sensitivity reaches for the similar process $pp\to H\to ZA\to l^+l^-b\bar b$. This simple exercise across the two processes, which is possible because the only kinematic difference between these are different widths for the Higgs bosons, in turn affecting minimally the efficiency of an experimental selection, enables us to expand the region of parameter space that can be tested to the case when $m_H\ge m_A+m_Z$. Furthermore, we extrapolate our results to full Run 3 data samples. We conclude that, while the high energy and luminosity stage of the LHC can afford one with increased sensitivity to the 2HDM in general, the recast analysis does not add anything to what already probed through the actual one.

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arXiv2020

Signatures of vector-like top partners decaying into new neutral scalar or pseudoscalar bosons

We explore the phenomenology of models containing one Vector-Like Quark (VLQ), $t'$, which can decay into the Standard Model (SM) top quark, $t$, and a new spin-0 neutral boson, $S$, the latter being either a scalar or pseudoscalar state. We parametrise the underlying interactions in terms of a simplified model which enables us to capture possible Beyond the SM (BSM) scenarios. We discuss in particular three such scenarios: one where the SM state is supplemented by an additional scalar, one which builds upon a 2-Higgs Doublet Model (2HDM) framework and another which realises a Composite Higgs Model (CHM) through partial compositeness. Such exotic decays of the $t'$ can be competitive with decays into SM particles, leading to new possible discovery channels at the Large Hadron Collider (LHC). Assuming $t'$ pair production via strong interactions, we design signal regions optimised for one $t'\rightarrow S t$ transition (while being inclusive on the other \bar{t'} decay, and vice versa), followed by the decay of $S$ into the two very clean experimental signatures $S\rightarrow γγ$ and $S\rightarrow Z(\rightarrow \ell^+\ell^-)γ$. We perform a dedicated signal-to-background analysis in both channels, by using Monte Carlo (MC) event simulations modelling the dynamics from the proton-proton to the detector level. Under the assumption of BR$(t' \rightarrow S t) = 100\%$, we are therefore able to realistically quantify the sensitivity of the LHC to both the $t'$ and $S$ masses, assuming both current and foreseen luminosities. This approach paves the way for the LHC experiments to surpass current VLQ search strategies based solely on $t'$ decays into SM bosons ($W^\pm, Z$, $h$).

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arXiv2020

Implications of light charged Higgs boson at the LHC Run III in the 2HDM

In this study, we focus on the bosonic decays of light charged Higgs boson (i.e., with $M_{H^\pm}<m_t$) in the 2-Higgs Doublet Model (2HDM) Type-I. To study the signal of such a charged Higgs state at the Large Hadron Collider (LHC), in a scenario where the $H^0$ boson is the Standard Model (SM)-like one already discovered, we assume that it decays mainly via $h^0W^{\pm *}$ and/or $H^\pm\to A^0W^{\pm *}$ (i.e., via an off-shell $W^{\pm}$ boson), which can reach a sizable Branching Ratio (BR) for $\tanβ\geq4$, when the exclusion bounds from $H^\pm\toτν$ and $c{s}$ searches get weaker. By using six Benchmark Points (BPs), which are consistent with current LHC constraints, we perform a Monte Carlo (MC) study and examine the sensitivity of the LHC to light charged Higgs boson decaying via the above bosonic modes and produced in top decay following both single top and top pair production processes. Our findings demonstrate that, when the integrated luminosity can reach 100 fb$^{-1}$, the LHC has the potential to either discover or rule out most of these BPs via either of these two production and decay channels or both.

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arXiv2020

A Guidebook to Hunting Charged Higgs Bosons at the LHC

We perform a comprehensive global analysis in the Minimal Supersymmetric Standard Model (MSSM) as well as in the 2-Higgs Doublet Model (2HDM) of the production and decay mechanisms of charged Higgs bosons $(H^\pm)$ at the Large Hadron Collider (LHC). Starting from the most recent experimental results (SM-like Higgs boson signal strengths and search limits for new Higgs boson states obtained at Run-1 and -2 of the LHC and previous colliders), from (both direct and indirect) searches for Supersymmetric particles as well as from flavor observables (from both $e^+e^-$ factories and hadron colliders) and upon enforcing theoretical constraints (vacuum stability, perturbativity, unitarity), we present precise predictions for $H^\pm$ cross sections and decay rates in different reference scenarios of the two aforementioned models in terms of the parameter space currently available, specifically mapped over the customary $(m_{A,H^\pm}, \tanβ)$ planes, including singling out specific Benchmark Points (BPs) amenable to phenomenological investigation. These include the $m_{h}^{{\rm mo}d+}$ and hMSSM configurations of the MSSM and the 2HDM Type-I, -II, -X and -Y. Such BPs are always close to (or coinciding with) the best fits of the theoretical scenarios to experimental data. We also briefly discuss the ensuing phenomenology for the purpose of aiding future searches for such charged Higgs boson states.

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arXiv2020

Scattering Interference effects on $H^+\to t\bar b$ Signals in MSSM Benchmark Scenarios

In this talk an investigation into the interference effects between the process $pp\to \bar{t}bH^+$ followed by the decay $H^+ \to t\bar{b}$ and the background process $pp \to t\bar{t}b\bar{b}$ is presented. The level of interference in parts of the parameter space is shown to be high and as such it may spoil the results of typical analyses which treat signal and background as independent. This is shown for two benchmarks of the MSSM.

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arXiv2019

Explaining Dijet Mass Excesses in ALEPH LEP2 Four-Jet Events with 2HDMs

In this paper, we address the observability of four-jet signatures from light neutral and charged Higgs bosons at LEP2 energies in the framework of 2-Higgs Doublet Models (2HDMs). The main signal production channels are via $e^+ e^- \to Ah$ and $H^+ H^-$ with subsequent quark decays of such final states into four-jets. Specifically, Type-I and -III realizations of a generic 2HDM (2HDM-I and -III, respectively) are adopted to show that there exist points (under the assumption that the heavy Higgs state $H$ is SM-like) for which $(m_h, m_A, m_{H^\pm}) \approx (80, 30, 55)$ GeV that can yield observable rates at LEP2 energies that can potentially explain the di-jet mass excesses seen recently in ALEPH data in a re-analysis of their four-jet samples, particularly so for the 2HDM-III.

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arXiv2019

Theory and Phenomenology of Two Higgs Doublet Type-II Seesaw Model at the LHC Run-2

We study the most popular scalar extension of the Standard Model, namely the Two Higgs doublet model, extended by a complex triplet scalar (2HDMcT). Such considering model with a very small vacuum expectation value, provides a solution to the massive neutrinos through the so-called type II seesaw mechanism. We show that the 2HDMcT enlarged parameter space allow for a rich and interesting phenomenology compatible with current experimental constraints. In this paper the 2HDMcT is subject to a detailed scrutiny. Indeed, a complete set of tree level unitarity constraints on the coupling parameters of the potential is determined, and the exact tree-level boundedness from below constraints on these couplings are generated for all directions. We then perform an extensive parameter scan in the 2HDMcT parameter space, delimited by the above derived theoretical constraints as well as by experimental limits. We find that an important triplet admixtures are still compatible with the Higgs data and investigate which observables will allow to restrict the triplet nature most effectively in the next runs of the LHC. Finally, we emphasize new production and decay channels and their phenomenological relevance and treatment at the LHC.

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