Neutral Higgs Boson Pair Research Articles

Parameter dependence and analysis of the 2HDM neutral Higgs boson pair production and decay at future lepton colliders

In this work, we present a study of the neutral Higgs bosons in the two Higgs doublet model (2HDM) in terms of their production processes and decay channels as a function of the model parameters. The analysis is performed for all four types of the 2HDM and the most promising processes and decay channels are identified for each type of the model. Several Higgs boson mass scenarios below and above the threshold of decay to gauge boson pair are introduced and the corresponding categories of final states are analyzed. The event analysis including collider beam spectrum and detector simulation shows that future lepton colliders have the potential to explore regions in the 2HDM parameter space, which have not yet been excluded by LHC, in a few weeks of operation. Final results are presented in terms of the signal distributions on top of the background and 95% CL exclusion and 5σ contours based on center of mass energy of s=500 GeV at the Compact Linear Collider (CLIC) or International Linear Collider (ILC).

LHC Higgs signatures from topflavor seesaw mechanism

We study LHC Higgs signatures from topflavor seesaw realization of electroweak symmetry breaking with a minimal gauge extension SU(2)⊗SU(2)⊗U(1). This elegant renormalizable construction singles out top quark sector (instead of all other light fermions) to join the new SU(2) gauge force. It predicts extra vector-like spectator quarks (T,B), new gauge bosons (W′,Z′), and a pair of neutral Higgs bosons (h,H). We demonstrate that for the lighter Higgs boson h of mass 125 GeV, this model predicts modified Higgs signal rates in h→γγ,WW⁎,ZZ⁎ channels via gluon fusions, in h→ττ¯ mode via vector boson fusions, and in h→bb¯ mode via gauge boson associate productions. We perform a global fit for our theory by including both direct search data (LHC and Tevatron) and indirect precision constraints. We further analyze the LHC discovery potential for detecting the heavier Higgs state H.

Pair production of neutral Higgs bosons from the left-right twin Higgs model via γγ collisions

The left-right twin Higgs (LRTH) model predicts the existence of the neutral Higgs bosons (h, φ0), which can be produced in pairs (φ0φ0, hh, φ0h) via γγ collisions at the next generation e+e− International Linear Collider (ILC). Our numerical results show that the production cross section of the neutral Higgs boson pair φ0φ0 can reach 8.8 fb. The subprocess γγ → φ0φ0 might be used to test the LRTH model in future ILC experiments.

Neutral Higgs boson pair production at the linear collider in the noncommutative standard model

We study the Higgs boson pair production at the linear collider in the noncommutative extension of the standard model using the Seiberg-Witten map of this to the first order of the noncommutative parameter ${\ensuremath{\Theta}}_{\ensuremath{\mu}\ensuremath{\nu}}$. Unlike the standard model (where the process is forbidden) here the Higgs boson pair directly interacts with the photon. We find that the pair production cross section can be quite significant for the noncommutative scale $\ensuremath{\Lambda}$ lying in the range 0.5 TeV to 1.0 TeV. Using the experimental (LEP 2, Tevatron, and global electroweak fit) bound on the Higgs mass, we obtain $626\text{ }\text{ }\mathrm{GeV}\ensuremath{\le}\ensuremath{\Lambda}\ensuremath{\le}974\text{ }\text{ }\mathrm{GeV}$.

Higgs boson decays and production in the left–right twin Higgs model

The left–right twin Higgs model predicts one neutral Higgs boson ϕ0 and it acquires mass mϕ0∼μr with the μ term, which can be lighter than half the SM-like Higgs boson mass in a portion of parameter space. Thus, the SM-like Higgs boson h can dominantly decay into a pair of light neutral Higgs bosons especially when mh is below the WW threshold. First, we examine the branching ratios of the SM-like Higgs boson decays and find that the new decay mode h→ϕ0ϕ0 is dominant for the case of mh>2mϕ0. Then we study the production via gluon fusion followed by the decay into two photons or two weak gauge bosons and found that the production rate can be significantly suppressed for some part of parameter space. Finally, we comparatively study the process γγ→h→bb¯ at ILC in the cases of mh>2mϕ0 and mh<2mϕ0, respectively. We find that these predictions can significantly deviated from the SM predictions, e.g., the gluon–gluon fusion channel, in the cases of mh>2mϕ0 and mh<2mϕ0, can be suppressed by about 80% and 45%, respectively. Therefor, it is possible to probe the left–right twin Higgs model via these Higgs boson production processes at the LHC experiment or in the future ILC experiment.

Pair production of Higgs bosons associated with Z boson in the left–right twin Higgs model at the ILC

The left–right twin Higgs (LRTH) model predicts the existence of three additional Higgs bosons: one neutral Higgs ϕ 0 and a pair of charged Higgs bosons ϕ ± . In this paper, we studied the production of a pair of charged and neutral Higgs bosons associated with standard model gauge boson Z at the ILC, i.e., e + e − → Z ϕ + ϕ − and e + e − → Z ϕ 0 ϕ 0 . We calculate the production rate and present the distributions of the various observables, such as, the distributions of the energy and the transverse momenta of final Z-boson and charged Higgs boson ϕ − , the differential cross section of the invariant mass of charged Higgs bosons pair, the distribution of the angle between charged Higgs bosons pair and the production angle distributions of Z-boson and charged Higgs boson ϕ − . Our numerical results show that, for the process e + e − → Z ϕ + ϕ − , the production rates are at the level of 10 − 1 fb with reasonable parameter values. For the process of e + e − → Z ϕ 0 ϕ 0 , we find that the production cross section are smaller than 6 × 10 − 3 fb in most of parameter space. However, the resonance production cross section can be significantly enhanced.

Neutral Higgs boson pair production at Linear Colliders

AbstractWe compute the one‐loop production cross section for neutral Higgs boson pairs at linear colliders from a generic two‐Higgs‐doublet model (2HDM). We identify important quantum effects associated to the triple‐Higgs boson self‐interactions – a genuine feature of the 2HDM, which is impossible to achieve in the Minimal Supersymmetric Standard Model (MSSM).

Higgs-pair production and decay in simplest little Higgs model

In the framework of the simplest little Higgs model (SLHM), we study the production of a pair of neutral CP-even Higgs bosons at the LHC. First, we examine the production rate and find that it can be significantly larger than the SM prediction. Then we investigate the decays of the Higgs-pair and find that for a low Higgs mass their dominant decay mode is h h → η η η η ( η is a CP-odd scalar) while h h → b b ¯ η η and h h → η η W W may also have sizable ratios. Finally, we comparatively study the rates of p p → h h → b b ¯ τ + τ − , p p → h h → b b ¯ γ γ , and p p → h h → W W W W in the SLHM and the littlest Higgs models (LHT). We find that for a light Higgs, compared with the SM predictions, all the three rates can be sizably enhanced in the LHT but severely suppressed in the SLHM; while for an intermediately heavy Higgs, both the LHT and SLHM can enhance sizably the SM predictions.

Search for Next-to-Minimal Supersymmetric Higgs Bosons in theh→aa→μμμμ,μμττChannels Usingpp¯Collisions ats=1.96 TeV

We report on a first search for production of the lightest neutral CP-even Higgs boson (h) in the next-to-minimal supersymmetric standard model, where h decays to a pair of neutral pseudoscalar Higgs bosons (a), using 4.2/fb of data recorded with the D0 detector at Fermilab. The a bosons are required to either both decay to mu^+mu^- or one to mu^+mu^- and the other to tau^+tau^-. No significant signal is observed, and we set limits on its production as functions of M_a and M_h.

Neutral Higgs boson pair production in photon-photon annihilation in the two Higgs doublet model

We study double Higgs production in photon-photon collisions as a probe of the new dynamics of Higgs interactions in the framework of two Higgs doublet models. We analyze neutral Higgs bosons production and decay in the fusion processes, $\ensuremath{\gamma}\ensuremath{\gamma}\ensuremath{\rightarrow}{S}_{i}{S}_{j}$, ${S}_{i}={h}^{0}$, ${H}^{0}$, ${A}^{0}$, and show that both ${h}^{0}{h}^{0}$ and ${A}^{0}{A}^{0}$ production can be enhanced by threshold effects in the region ${E}_{\ensuremath{\gamma}\ensuremath{\gamma}}\ensuremath{\approx}2{m}_{H\ifmmode\pm\else\textpm\fi{}}$. Resonant effects due to the heavy Higgs ${H}^{0}$ can also play a role in the cross section enhancement when it is allowed to decay to two light $CP$-even ${h}^{0}$ or to two light $CP$-odd ${A}^{0}$ scalars. We have scanned the allowed parameter space of the two Higgs doublet model and found a vast region of the parameter space where the cross section is 2 orders of magnitude above the standard model cross section. We further show that the standard model experimental analysis can be used to discover or to constrain the two Higgs doublet model parameter space.

Nonstandard Higgs Boson Decays

This review summarizes the motivations for and the phenomenological consequences of nonstandard Higgs boson decays, with an emphasis on final states containing a pair of non–standard model particles that subsequently decay to standard model particles. Typically these non–standard model particles form part of a “hidden” sector, for example a pair of neutral Higgs bosons or a pair of unstable neutralinos. We emphasize that such decays allow for a Higgs substantially below the standard model Higgs Large Electron-Positron Collider limit of 114 GeV. A Higgs with standard model WW, ZZ, and top couplings and a mass near 100 GeV eliminates the fine-tuning problems of many beyond the standard model theories, in particular supersymmetric models, and leads to excellent consistency with precision electroweak data.

Neutral Higgs Boson Pair Production in Standard Model with the Fourth Generation Quarks at LHC**The project supported in part by National Natural Science Foundation of China

We investigated the neutral Higgs boson pair production at the CERN Large Hadron Collider (LHC) in the SM with four families. We found that the gluon-gluon fusion mode is the most dominant one in producing neutral Higgs boson pair at the LHC, and it can be used to probe the trilinear Higgs coupling. If the heavy quarks of the fourth generation really exist within the SM, they can manifest their effect on the cross section of the Higgs pair production process at the LHC. Our numerical results show that there will be neutral Higgs boson pair production events per year if the next generation heavy quarks really exist, while there will be only events produced per year if there are only three families in the SM.

The $\gamma \gamma \rightarrow H^0 H^0$ decay in non-commutative quantum electrodynamics

We study the possibility of detecting noncommutative QED through neutral Higgs boson pair production at (gamma--gamma) collider. This is based on the assumption that H^0 interacts directly with photon as suggested by symmetry considerations. The sensitivity of the cross-section to the noncommutative scale (Lambda_{NC}) and Higgs mass is investigated.

Pair production of neutral Higgs bosons through noncommutative QED interactions at linear colliders

We study the feasibility of detecting noncommutative (NC) QED through neutral Higgs boson (H) pair production at linear colliders (LC). This is based on the assumption that H interacts directly with photon in NCQED as suggested by symmetry considerations and strongly hinted by our previous study on ${\ensuremath{\pi}}^{0}$-photon interactions. We find the following striking features as compared to the standard model (SM) result: (1) generally larger cross sections for an NC scale of order 1 TeV; (2) completely different dependence on initial beam polarizations; (3) distinct distributions in the polar and azimuthal angles; and (4) day-night asymmetry due to the Earth's rotation. These will help to separate NC signals from those in the SM or other new physics at LC. We emphasize the importance of treating properly the Lorentz noninvariance problem and show how the impact of the Earth's rotation can be used as an advantage for our purpose of searching for NC signals.

The processes γγ→γγ, γ Z, ZZ

The Standard Model contributions to the processes γγ→ γγ, γZ and ZZ at sufficiently high energies, are found to be helicity conserving and almost purely imaginary. This is due to the W-loop contribution, which is much bigger than the fermionic ones at such energies. Thus the structure of these amplitudes acquires an impressive simplicity at high energies. Nothing like this appears in other process like e.g. the production of a pair of neutral Higgs bosons.

Supersymmetric Higgs boson pair production at hadron colliders

We study the pair production of neutral Higgs bosons through gluon fusion at hadron colliders in the framework of the Minimal Supersymmetric Standard Model. We present analytical expressions for the relevant amplitudes, including both quark and squark loop contributions, and allowing for mixing between the superpartners of left- and right-handed quarks. Squark loop contributions can increase the cross section for the production of two CP-even Higgs bosons by more than two orders of magnitude, if the relevant trilinear soft breaking parameter is large and the mass of the lighter squark eigenstate is not too far above its current lower bound. In the region of large $\tan \beta$, neutral Higgs boson pair production might even be observable in the $4 b$ final state during the next run of the Tevatron collider.

Lightest neutral Higgs boson pair production in photon-photon collisions in the minimal supersymmetric standard model

The cross sections for the lightest neutral Higgs boson pair production at the one-loop level in photon-photon collisions are calculated in the minimal supersymmetric standard model. We find that the contributions to the lightest Higgs boson pair production cross sections arising from the genuine supersymmetric virtual particles dominate over those arising from the virtual particles in the two-Higgs-doublet model (2HDM) if there is mixing between the right- and left-handed top squarks; otherwise, the contributions from the 2HDM are dominant. We present detailed numerical results of the cross sections of the process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\ensuremath{\gamma}\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\gamma}}{h}_{0}{h}_{0}$ in both beamstrahlung and laser backscattering photon modes at the Next Linear Collider. The cross sections are typically in the range ${10}^{\ensuremath{-}3}$--${10}^{5}\phantom{\rule{0ex}{0ex}}\mathrm{fb}$ depending on the choice of the mass of the lightest neutral Higgs boson, $\mathrm{tan}\ensuremath{\beta},$ and photon collision modes, especially whether there is mixing between the top squarks.

HIGGS BOSON DISCOVERY POTENTIAL BEYOND THE MINIMAL STANDARD MODEL

Detailed studies of neutral and charged Higgs boson pair production with full statistic detector simulations around [Formula: see text] with 500 pb−1 are presented in the context of a review of the Higgs boson discovery potential at LEP200. Already in the first phase of LEP200, a significant increase of the mass parameter space compared to LEP1 for the discovery of nonminimal Higgs bosons will be possible, while the mass range for the discovery of the minimal Standard Model Higgs boson will increase only marginally. The requirements for a decisive test of the Minimal Supersymmetric extension of the Standard Model (MSSM) at a later stage of LEP200 are discussed. A sensitivity mass range is given for charged Higgs bosons.