The pairwise production of neutral Higgs bosons is analyzed in the context of the future linear colliders, such as the ILC and CLIC, within the general Two-Higgs-Doublet Model (2HDM). The corresponding cross-sections are computed at the one-loop level in full compliance with the current phenomenological bounds and the stringent theoretical constraints inherent to the consistency of the model. We uncover regions across the 2HDM parameter space, mainly for low tanβnear 1 and moderate values of the relevant lambda_5 parameter, wherein the radiative corrections to the Higgs-pair production cross sections can comfortably reach 50% This behavior can be traced back to the enhancement capabilities of the trilinear Higgs self-interactions -- a trademark feature of the 2HDM, with no counterpart in the Minimal Supersymmetric Standard Model. Interestingly enough, the quantum effects are positive for energies around 500 GeV, thereby producing a significant enhancement in the expected number of events precisely around the fiducial startup energy of the ILC. The Higgs-pair production rates can be substantial, typically amounting to a few thousand events per 500 inverse femtobarn of integrated luminosity. In contrast, the corrections are negative in the highest energy range (1 TeV). We also compare the exclusive pairwise production of Higgs bosons with the inclusive gauge boson fusion channels leading to 2H+X finals states, and also with the exclusive triple Higgs boson production. We find that these multiparticle final states can be highly complementary in the overall Higgs bosons search strategy.
A $ Z_3 $ symmetric 3-Higgs Doublet Model (3HDM) with two inert doublets and one active doublet (that plays the role of the Higgs doublet), the so-called I(2+1)HDM, is studied. We discuss the behaviour of this 3HDM realisation when one allows for a $ Z_3 $ soft breaking term. Such a symmetry enables the presence of a two-component Dark Matter (DM) scenario in the form of "Hermaphrodite DM", where the two inert candidates have opposite CP parity and are protected by this discrete symmetry from decaying into Standard Model (SM) particles. Furthermore, the two DM states are potentially distinguis…
We introduce a 3-Higgs Doublet Model (3HDM) with two Inert (or dark) scalar doublets and an active Higgs one, hence termed I(2+1)HDM, in the presence of a discrete $Z_3$ symmetry acting upon the three doublet fields. We show that such a construct yields a Dark Matter (DM) sector with two mass-degenerate states of opposite CP parity, both of which contribute to DM dynamics, which we call \textit{Hermaphrodite DM}, distinguishable from a (single) complex DM candidate. We show that the relic density contributions of both states are equal, saturating the observed relic density compliant with (in)d…
Following the discovery of a Higgs boson, there has been renewed interest in the general 2-Higgs-Doublet Model (2HDM). A model with One Inert Doublet plus One Higgs Doublet (I(1+1)HDM), where one of the scalar doublets is "inert" (since it has no vacuum expectation value and does not couple to fermions) has an advantage over the 2HDM since it provides a good Dark Matter (DM) candidate, namely the lightest inert scalar. Motivated by the existence of three fermion families, here we consider a model with two scalar doublets plus one Higgs doublet (I(2+1)HDM), where the two scalar doublets are ine…
We perform a comprehensive study of The Higgs potential of the two Higgs doublet model extended by a real triplet scalar field $Δ$. This model, dubbed $2\mathcal{HDM+T}$, has a rich Higgs spectrum consisting of three CP-even Higgs $h_{1,2,3}$, one CP-odd $A_0$ and two pairs of charged Higgs $H^\pm_{1,2}$. First, we determine the perturbative unitarity constraints and a set of non trivial conditions for the boundedness from below (BFB). Then we derive the Veltman conditions by considering the quadratic divergencies of Higgs boson self energies in $2\mathcal{HDM+T}$. We find that the parameter s…
The $Z_3$ soft breaking in the I(2+1)HDM and its cosmological probes
Facultad de Ciencias Físico-Matemáticas, Benemérita Universidad Autónoma de Puebla（普埃布拉自治理工医科大学理学院）；Facultad de Ciencias de la Electrónica, Benemérita Universidad Autónoma de Puebla（普埃布拉自治理工大学电子科学学院）；Dual CP Institute of High Energy Physics（高能物理双CP研究所）；Facultad de Ciencias, Universidad de Colima（科利马大学理学院）；School of Physics and Astronomy, University of Southampton（南安普顿大学物理与天文学院）；Department of Physics and Astronomy, Uppsala University（乌普萨拉大学物理与天文系）；Division of Liberal-Arts, Kogakuin University（工机大学文理学部）；Department of Natural Science, International Christian University（国际基督教大学自然科学系）
We present the complete set of continuous maximal symmetries that the potential of an $n$-Higgs Doublet Model ($n$HDM) should satisfy for natural Standard Model (SM) alignment. As a result, no large mass scales or fine-tuning is required for such alignment, which still persists even if these symmetries were broken softly by bilinear mass terms. In particular, the Maximal Symmetric $n$HDM (MS-$n$HDM) can provide both natural SM alignment and quartic coupling unification up to the Planck scale. Most remarkably, we show that the MS-2HDM is a very predictive extension of the SM governed by two onl…
Maximally Symmetric $n$-Higgs Doublet Models (MS-$n$HDMs)define very economic settings that enable sharp Higgs-sector predictions beyond the Standard Model (SM) potentially testable at high-energy colliders. The scalar potential of a MS-$n$HDM obeys an $\mathrm{Sp(2}n)$ symmetry, which is softly broken by bilinear scalar masses and explicitly by hypercharge and Yukawa couplings through renormalisation-group effects. The $\mathrm{Sp(2}n)$ also ensures natural SM alignment and allows for quartic coupling unification up to the Planck scale. As typical examples, we consider maximally symmetric rea…
We study an extension of the Standard Model (SM) in which two copies of the SM Higgs doublet are added to the scalar sector. These extra doublets do not develop a vacuum expectation value, hence, they are \textit{inert}. This essentially leads to a 3-Higgs Doublet Model (3HDM) with 2 inert and 1 active scalar doublets, which we denote as I(2+1)HDM. We allow for CP-violation in the \textit{inert} sector, where the lightest \textit{inert} state is protected from decaying to SM particles through the conservation of a $Z_2$ symmetry, so that it is a Dark Matter (DM) candidate. For this scenario, w…
We consider triple Higgs boson production at a future 100 TeV proton-proton collider. We perform a survey of viable final states and compare and contrast triple production to Higgs boson pair production. Focussing on the $hhh \rightarrow (b\bar{b}) (b\bar{b}) (γγ)$ final state, we construct a baseline analysis for the Standard Model scenario and simple deformations, demonstrating that the process merits investigation in the high-luminosity phase of the future collider as a new probe of the self-coupling sector of the Higgs boson.
We investigate the potential of future TeV linear e^+e^- colliders to observe singly-charged Higgs bosons ($H^\pm$) via the coupling $H^\pm W^\mp Z$, which would signal the existence of exotic Higgs representations. In the context of a Higgs-triplet model compatible with the electroweak oblique parameters, we estimate the cross section for pro- ducing charged Higgs-triplet bosons that couple predominantly to $W$ and $Z$ bosons in 0.5--2 TeV-$e^+e^-$ colliders. The principal backgrounds are evaluated and the viability of the signal is discussed and illustrated.
The signature of heavy fermionic triplets belonging to Type III seesaw at the International Linear Collider (ILC) is probed. Presence of charged fermionic triplets upto a mass of about $ 750$ GeV could be established through single production at a 1 TeV ILC with moderate luminosity of 300 fb$^{-1}$, assuming a fermion triplet-electron mixing of about 0.05. Unlike the case of LHC, the production process is highly sensitive to the mixing, making the process interesting. The single production of neutral triplet is found to be somewhat harder, considering the large SM background present. Pair prod…
We study the triple Higgs self-coupling at future $e^{+}e^{-}$ colliders energies, with the reactions $e^{+}e^{-}\to b \bar b HH$ and $e^{+}e^{-}\to t \bar t HH$. We evaluate the total cross section of $b\bar bHH$, $t\bar tHH$ and calculate the total number of events considering the complete set of Feynman diagrams at tree-level. The sensitivity of the triple Higgs coupling is considered in the Higgs mass range 110-190 $GeV$, for the energy which is expected to be available at a possible Next Linear $e^{+}e^{-}$ Collider with a center-of-mass energy $800, 1000, 1500$ $GeV$ and luminosity 1000 …
The novel feature of a Higgs-triplet representation is a nonzero tree-level coupling of $H^+ W^- Z$, which is absent in all Higgs-doublet models. We study the associated production of a singly-charged Higgs boson of the Higgs-triplet representation with a $W$ or $Z$ boson at hadron colliders, followed by the $H^+ \to W^+ Z$ decay. We find that the $2\ell+4j$ final state gives an interesting level of signal with a negligible background, plus it allows a full mass reconstruction of the charged-Higgs boson. The cover range of the charged-Higgs mass is between 110 and 200 GeV.
The production of triple Higgs $(H^+H^-H^0)$, $(H^+H^-h^0)$ and pair wise charged Higgs boson $(H^+H^-)$ is studied in the context of future linear colliders within the Two-Higgs Doublet Model (2HDM) type II. The aim is to compare sources of charged Higgs pair through the above processes, i.e., double and triple Higgs production. Cross-sections are calculated at the leading order in 2HDM type II and Minimal Supersymmetric Standard Model (MSSM). Several orders of magnitude ($\sim 10^{4}$) enhancement is observed in 2HDM compared to MSSM, while no sizable enhancement is seen in muon collider ver…
We extend the minimal supersymmetric standard model with bilinear R-parity violation to include a pair of Higgs triplet superfields. The neutral components of the Higgs triplets develop small vacuum expectation values (VEVs) quadratic in the bilinear R-parity breaking parameters. In this scheme the atmospheric neutrino mass scale arises from bilinear R-parity breaking while for reasonable values of parameters the solar neutrino mass scale is generated from the small Higgs triplet VEVs. We calculate neutrino masses and mixing angles in this model and show how the model can be tested at future c…
At a high energy $ep$ collider, such as the Large Hadron-Electron Collider (LHeC) which is being planned at CERN, one can access the $WWγ$ vertex exclusively in charged current events with a radiated photon, with no interference from the $WWZ$ vertex. We find that the azimuthal angle between the jet and the missing momentum in each charged current event is a sensitive probe of anomalous $WWγ$ couplings, and show that for quite reasonable values of integrated luminosity, the LHeC can extend the discovery reach for these couplings beyond all present experimental bounds.
We consider the neutral triple gauge boson production process in the context of large extra dimensions (LED) model including the Kaluza-Klein (KK) excited gravitons at future linear colliders, say ILC(CLIC). We consider $γγγ, γγZ, γZ Z$ and $ZZZ$ production processes, and analyse their impacts on both the total cross section and some key distributions. These processes are important for new physics searches at linear colliders. Our results show that KK graviton exchange has the most significant effect on \eerzz among the four processes with relatively small $M_S$, while it has the largest effec…
We consider the possibility that the dark matter particle is a scalar WIMP messenger associated to neutrino mass generation, made stable by the same symmetry responsible for the radiative origin of neutrino mass. We focus on some of the implications of this proposal as realized within the singlet-triplet scotogenic dark matter model.We identify consistent parameter sets consistent both with neutrino mass and the observed dark matter abundance. Finally we characterize the expected phenomenological profile of heavy Higgs boson physics at the LHC as well as at future linear Colliders.
In this work we analyse the triple Higgs boson production cross section at hadron colliders via gluon fusion, and present for the first time the full set of QCD NNLO corrections in the heavy top limit. In order to account for finite top mass effects we perform two different reweighting procedures, and study the dependence of the result on the choice of the approximation. Combining the most accurate predictions available to date, we present the following result for the total NNLO cross section for triple Higgs boson production at a 100 TeV collider: $σ_\text{NNLO}=5.56^{+5\%}_{-6\%} \pm 20\%$ f…
The $WW$ production is the primary channel to directly probe the triple gauge couplings. We analyze the $e^+ e^- \rightarrow W^+ W^-$ process at the proposed Circular Electron-Positron Collider (CEPC), and find that the anomalous triple gauge couplings and relevant dimension six operators can be probed up to the order of $10^{-4}$. We also estimate constraints at the 14 TeV LHC, with both 300 fb$^{-1}$ and 3000 fb$^{-1}$ integrated luminosity from the leading lepton $p_T$ and azimuthal angle difference $Δϕ_{ll}$ in the di-lepton channel. The constrain is somewhat weaker, up to the order of $10…
CP violation from physics beyond the Standard Model may reside in triple boson vertices of the electroweak theory. We review the effective theory description and discuss how CP violating contributions to these vertices might be discerned by electric dipole moments (EDM) or diboson production at the Large Hadron Collider (LHC). Despite triple boson CP violating interactions entering EDMs only at the two-loop level, we find that EDM experiments are generally more powerful than the diboson processes. To give example to these general considerations we perform the comparison between EDMs and collid…
The signatures of heavy fermionic triplets ($Σ$) arising in scenarios like Type III seesaw model are probed through their direct production and subsequent decay at high energy electron-positron collider. Unlike the case of LHC, the production process has strong dependence on the mixing parameter ($V_{e,μ}$), making the leptonic collider unique to probe such mixing. We have established that with suitably chosen kinematic cuts, a 1 TeV $e^+e^-$ collider could probe the presence of $Σ$ of mass in the range of 500 GeV having $V_e=0.05$ with a few inverse femto barn luminosity through single produc…
We investigate the collider phenomenology of the scalar triplet particles in the Type-II seesaw model at a 100 TeV $pp$ collider. Depending on triplet vacuum expectation value $v_Δ$, the dominant discovery channels could be $H^{++} H^{--}$ and $H^{\pm\pm}H^\mp$. We find the $H^{\pm\pm}H^\mp\to W^\pm W^\pm h W^\mp/\ell^\pm \ell^\pm h W^\mp$ channels are promising for both model discovery at relatively large $v_Δ$ and determination of the Higgs portal couplings $λ_4$ and $λ_5$. We also find that these two channels are complementary to indirect determination of $λ_4$ from future precise measureme…
The quartic self-coupling of the Standard Model Higgs boson can only be measured by observing the triple-Higgs production process, but it is challenging for the Large Hadron Collider (LHC) Run 2 or International Linear Collider (ILC) at a few TeV because of its extremely small production rate. In this paper, we present a detailed Monte Carlo simulation study of the triple-Higgs production through gluon fusion at a 100 TeV hadron collider and explore the feasibility of observing this production mode. We focus on the decay channel $HHH\rightarrow b\bar{b}b\bar{b}γγ$, investigating detector effec…
The experimental reconstruction of the Higgs self-energy potential is essential to a verification of the Higgs boson's role in spontaneous electroweak symmetry breaking. The first step towards this goal, the measurement of the triple Higgs self-coupling, can possibly be accomplished at the next generation of linear colliders. Here we present a background study of the most promising channel, double Higgs-strahlung off a Z boson, e+e- -> HHZ, with the subsequent decay H -> b bbar, and evaluate the feasibility of its measurement.
In this work, we investigate the prospects of future $e^{+}e^{-}$ colliders in testing a Higgs triplet model with a scalar triplet and a scalar singlet under $SU(2)$. The parameters of the model are fixed so that the lightest $CP-$even state corresponds to the Higgs particle observed at the LHC at around $125$ GeV. This study investigates if the second heaviest $CP-$even, the heaviest $CP-$odd and the singly charged states can be observed at existing and future colliders by computing their accessible production and decay channels. In general, the LHC is not well equipped to produce a Higgs bos…
In this paper such processes which act as a source of double Higgs production (2H) as well as triple Higgs production (3H) at future linear colliders are analyzed with in 2HDM and its special type-II, MSSM at various center of mass energies. The main aim of this study is to compute and also compare the cross-sections in double and triple Higgs production processes at the future linear colliders. The production of double charged Higgs boson ($H^{+}H^{-}$) as well as triple Higgs boson ($H^{+}H^{-}H^{0}$),($H^{+}H^{-}h^{0}$) are considered for study at two center of mass energies (1.5 TeV and 3 …
We study the search potential of heavy triplet leptons in Type III Seesaw mechanism at future high-energy and high-luminosity muon colliders. The impact of up-to-date neutrino oscillation results is taken into account on neutrino parameters and the consequent decay patterns of heavy leptons in Type III Seesaw. The three heavy leptons in the Casas-Ibarra parametrization with diagonal unity matrix are distinguishable in their decay modes. We consider the pair production of charged triplet leptons $E^+ E^-$ through both $μ^+μ^-$ annihilation and vector boson fusion (VBF) processes. The leading-or…
In this study we consider an extension of the Standard Model with a complex hypercharge zero triplet scalar. In this scenario one of the charged Higgs bosons remains purely triplet and does not couple to the fermions, making it elusive at colliders. Also the physical pseudoscalar is a pure triplet and this purity makes it a suitable dark matter candidate without the need of discrete symmetries, unlike other extensions. The bounds from relic density and direct dark matter search experiments select its mass to be $\sim 1.35-1.60$ TeV. The pure triplet charged Higgs gives rise to displaced signat…
We investigate the possibility of probing the triplet Higgs boson sector via single charged Higgs production in the process $e^+ e^- \to H^+ l ν_l$, at high energy electron-positron colliders, using the tree level $H^+W^-Z$ coupling which is a unique feature of such models. We find that even LEP-200 can give nontrivial information upto $M_{H^{\pm}} \simeq 120 $ GeV if the doublet -triplet mixing is not restricted by the current value of the $ρ$ parameter which is the case in models with a custodial symmetry. Further we point out that in such models, the 4-body, tree level decay $H^+ \to W^*Z^*…
One of the most challenging tasks for future high-luminosity electron-positron colliders is to extract Higgs triple coupling. It was proposed that this can be carried out via the precisely measuring the cross section of ZH associated production up to $0.4\%$. In this paper, we example the possible heavy pollution from Higgs-top anomalous coupling. Our numerical results show that the pollution is small for $\sqrt{s}_{e^+e^-}= 240 GeV$. However for the higher energy collider, pollution is sizable, which should be taken into account. We further explored the possibility to measure CP-violated Higg…
The $WW$ production is the primary channel to directly probe the triple gauge couplings. We first analyze the $e^+ e^- \rightarrow W^+ W^-$ process at the future lepton collider, China's proposed Circular Electron-Positron Collider (CEPC). We use the five kinematical angles in this process to constrain the anomalous triple gauge couplings and relevant dimension six operators at the CEPC up to the order of magnitude of $10^{-4}$. The most sensible information is obtained from the distributions of the production scattering angle and the decay azimuthal angles. We also estimate constraints at the…
In this paper, we study the triple top quark production at the future high-energy proton-proton colliders to probe the four-fermion interactions involving three top quarks. We employ the Standard Model Effective Field Theory (SMEFT) to find the upper limits at $95\%$ CL on the Wilson coefficients of these kinds of four-fermion operators. We consider a detailed analysis with a unique signal signature of two same-sign leptons. A full simulation chain includes all the relevant backgrounds, realistic detector simulations and a cut-based technique are taken into account. This study is presented for…
We study double Higgs production at the future Linear Collider in the framework of the Two Higgs Doublet Models through the following channels: $e^+e^- \to Φ_i Φ_j Z$, $Φ_i=h^0, H^0, A^0, H^\pm$. All these processes are sensitive to triple Higgs couplings. Hence observations of them provide information on the triple Higgs couplings that help reconstructing the scalar potential. We also discuss the double Higgs-strahlung $e^+e^- \to h^0 h^0 Z$ in the decoupling limit where $h^0$ mimics the SM Higgs boson. The processes $e^+e^- \to h^0 h^0 Z$ and $e^+e^- \to h^0 H^0 Z$ are also discussed in the …
In the framework of the $\mathcal{CP}$ conserving Two Higgs Doublet Model (2HDM), type I and II, we study the triple Higgs couplings with at least one light $h$ Higgs boson that is identified by the 125 GeV Higgs boson. We define benchmark planes that exhibit large values of triple Higgs couplings, while being in agreement with all experimental and theoretical constraints. Finally, we analyze the impact of the triple Higgs couplings on the production cross section of two neutral Higgs bosons in two channels, $σ(e^+e^-\to h_i h_j Z)$ and $σ(e^+e^- \to h_i h_j ν\barν)$ with $h_i h_j = hh, hH, HH…
The extension of the Standard Model (SM) with two complex $SU(2)_{L}$ scalar triplets enables one to have the Type II seesaw mechanism operative consistently with texture-zero neutrino mass matrices. This framework predicts additional doubly charged, singly charged and neutral spinless states. We show that, for certain values of the model parameters, there is sufficient mass splitting between the two doubly charged states ( $H_1^{\pm\pm}, H_2^{\pm\pm}$) that allows the decay $H_1^{\pm\pm} \to H_2^{\pm\pm} h $, and thus leads to a unique signature of this scenario. We show that the final state …
We investigate the production of three Higgs bosons at a proton-proton collider running at a centre-of-mass energy of 100 TeV, all of which decay into $b$-jets. This final state encapsulates by far the largest fraction of the total cross section of triple Higgs boson production, approximately $20\%$. We examine, by constructing detailed phenomenological analyses, two scenarios: (i) one in which the triple and quartic Higgs boson self-couplings are modified independently by new phenomena with respect to their Standard Model (SM) values and (ii) an extension of the SM by a gauge-singlet scalar t…
Much theoretical effort and automatization are required to confront new physics models with experimental data for many types of particle reactions at future colliders. In this context, we extend GRACE, an automatic calculation system for invariant amplitudes, to incorporate particles and interactions in the Georgi-Machacek model. With the extended GRACE system, we study fermiophobic Higgs boson production processes at $e^+ e^-$ and $e^- e^-$ colliders in the model. The results show some advantages of $e^- e^-$ colliders over $e^+ e^-$ colliders for new physics search and thus its complementary…
We explore the detection potential of the four lepton production processes $e^{+}e^{-} \rightarrow l^{+} νl^{\prime -}\overlineν$ for anomalous contributions to the triple boson vertices at proposed future high energy colliders with center-of-mass energies of 500 GeV and 1 TeV. The predicted bounds are of the order of a few percent for the $CP$-even couplings $κ_{V}$ (V=$γ$,Z) at the higher energy; we show that these limits can be improved by as much as a factor of two through suitable phase space cuts. A polarized beam facility, with its ability to access helicity information, could provide c…
We derive bounds on Higgs and gauge--boson anomalous interactions using the CDF data for the process $p \bar{p} \to γγγ+ X$. We use a linearly realized $SU_L(2) \times U_Y(1)$ invariant effective Lagrangian to describe the bosonic sector of the Standard Model, keeping the fermionic couplings unchanged. All dimension--six operators that lead to anomalous Higgs interactions involving $γ$ and $Z$ are considered. We also show the sensitivity that can be achieved for these couplings at Fermilab Tevatron upgrades.
We analyzed the triple Higgs boson self-coupling at future $e^{+}e^{-}$ colliders energies, with the reactions $e^{+}e^{-}\to b \bar b HH, t \bar t HH$. We evaluate the total cross-sections for both $b\bar bHH$ and $t\bar tHH$, and calculate the total number of events considering the complete set of Feynman diagrams at tree-level. We vary the triple coupling $κλ_{3H}$ within the range $κ=-1$ and +2. The numerical computation is done for the energies expected to be available at a possible Future Linear $e^{+}e^{-}$ Collider with a center-of-mass energy $800, 1000, 1500$ $GeV$ and a luminosity 1…
We review selected results for Higgs boson production at Linear Colliders in the framework of the general Two-Higgs-Doublet Model (2HDM). We concentrate on the analysis of i) the pairwise production of neutral Higgs bosons (hA,HA); and ii) the neutral Higgs boson-strahlung modes (hZ, HZ). We identify sizable production rates, in the range of 10-100 fb for center-of-mass energies of 0.5 TeV, alongside with large quantum effects (up to 50 %), which we can fundamentally track down to the enhancement power of the triple-Higgs self-interactions. This constitutes a telltale signature of the 2HDM, wi…
The Higgs sector of the standard model can be extended by introducing an $SU(2)_L$ Higgs triplet $Δ$ to generate the tiny neutrino masses in the framework of type-II seesaw mechanism. In this paper, we study the pair production of the introduced Higgs triplet at future $e^{-}p$ colliders. The corresponding production cross sections via vector boson fusion process at FCC-ep and ILC$\otimes$FCC are predicted, where the production of a pair of doubly charged Higgs is found to be dominant and then used to investigate the collider phenomenology of the Higgs triplet. Depending on the size of the Hig…
Within the framework of the $\cal CP$ conserving Two Higgs Doublet Models (2HDM) type I and II we investigate the di-Higgs production at future $e^+e^-$ colliders in order to find effects coming from triple Higgs couplings. We define and explore some benchmark planes that show large values of these couplings, still in agreement with all the relevant theoretical and experimental constraints. Within those planes two production channels are considered: $e^+e^-\to h_ih_jZ$ and $e^+e^-\to h_ih_jν\barν$, with $h_ih_j=hh,\ HH\ \mathrm{and}\ AA$. We discuss on the sensitivity to $κ_λ:=λ_{hhh}/λ_{hhh}^…
The observation of Higgs pair production at high-energy colliders can give evidence for the presence of a triple Higgs coupling. However, the actual determination of the value of this coupling is more difficult. In the context of general models for new physics, double Higgs production processes can receive contributions from many possible beyond-Standard-Model effects. This dependence must be understood if one is to make a definite statement about the deviation of the Higgs field potential from the Standard Model. In this paper, we study the extraction of the triple Higgs coupling from the pro…
We study the scalar triplet extension of the standard model with a low cutoff, preventing large corrections to the quadratic masses that would otherwise worsen the hierarchy problem. We explore the reach of LISA to test the parameter space region of the scalar potential (not yet excluded by Higgs to diphoton measurements) in which the electroweak phase transition is strongly first-order and produces sizeable gravitational waves. We also demonstrate that the collider phenomenology of the model is drastically different from its renormalizable counterpart. We study the reach of the LHC in ongoing…
We propose a novel kinematic method to expedite the discovery of the double Higgs ($hh$) production in the $\ell^+\ell^- b \bar{b} + E_T \hspace{-0.52cm} \big / ~$ final state. We make full use of recently developed kinematic variables, as well as the variables $\it Topness$ for the dominant background (top quark pair production) and $\it Higgsness$ for the signal. We obtain a significant increase in sensitivity compared to the previous analyses which used sophisticated algorithms like boosted decision trees or neutral networks. The method can be easily generalized to resonant $hh$ production …
In the present work we study the implications at the future $e^+e^-$ colliders of the modified interaction vertices $WWH$, $WWHH$, $HHH$ and $HHHH$ within the context of the non-linear effective field theory given by the Electroweak Chiral Lagrangian. These vertices are given by four parameters, $a$, $b$, $κ_3$ and $κ_4$, respectively, that are independent and without any constraint from symmetry considerations in this non-linear effective Lagrangian context, given the fact the Higgs field is a singlet. This is in contrast to the Standard Model, where the vertices are related by $V_{WWH}^{\rm …
We study the production of three gauge bosons at the next generation of linear $e^+e^-$ colliders operating in the $γγ$ mode. The processes $γγ\rightarrow W^+W^-V$ ($V=Z^0$, or $γ$) can provide direct information about the quartic gauge-boson couplings. We analyze the total cross section as well as several dynamical distributions of the final state particles including the effect of kinematical cuts. We find out that a linear $e^+e^-$ machine operating in the $γγ$ mode will produce 5--10 times more three-gauge-boson states compared to the standard $e^+e^-$ mode at high energies.
We consider the production of singly charged Higgs bosons in the Higgs triplet and two Higgs doublet models. We evaluate the cross sections for the pair production and the single production of charged higgses at linear collider. The decay modes of $H^+$ and the Standard Model backgrounds are considered. We analyze the possibilities to differentiate between triplet and two Higgs doublet models.
ATLAS and CMS have discovered a Standard Model Higgs-like particle. One of the main discovery channels is the Higgs decay to two photons, which, at the moment, seems to be considerably enhanced over the Standard Model expectation. Models with additional charged matter coupling to the Higgs sector can enhance or decrease the Higgs to two photons branching ratio. We take this as motivation to confront the so-called Georgi-Machacek model of Higgs triplets with the results of recent searches for a SM Higgs boson performed at the LHC. We also investigate the model in regions of the allowed paramete…
In this paper the triple Higgs production in a general two Higgs doublet model (2HDM) is studied. The production process is e+e- -> H+H-H0 followed by the charged Higgs decay to a pair of tau nu and the neutral Higgs decay to bb. The alternative process H+W-H0 is also included as a source of charged Higgs signal in the analysis. The focus is on a future e+e- linear collider operating at sqrt(s) = 1.5 TeV. The final state under consideration (tau tau bb ETmiss) is suitable for electroweak background rejection using the b-tagging tools. It is shown that although the signal cross section is small…
