No Arabic abstract
We revisit the production of a single Higgs boson from direct gamma gamma -scattering at a photon collider. We compute the total cross section sigma(gamma gamma to h) (for h=h0, H0, A0), and the strength of the effective g_{h gamma gamma} coupling normalized to the Standard Model (SM), for both the general Two-Higgs-Doublet Model (2HDM) and the Minimal Supersymmetric Standard Model (MSSM). In both cases the predicted production rates for the CP-even (odd) states render up to 10^4 (10^3) events per 500 invfb of integrated luminosity, in full consistency with all the theoretical and phenomenological constraints. Depending on the channel the maximum rates can be larger or smaller than the SM expectations, but in most of the parameter space they should be well measurable. We analyze how these departures depend on the dynamics underlying each of the models, supersymmetric and non-supersymmetric, and highlight the possible distinctive phenomenological signatures. We demonstrate that this process could be extremely helpful to discern non-supersymmetric Higgs bosons from supersymmetric ones. Furthermore, in the MSSM case, we show that gammagamma-physics could decisively help to overcome the serious impasse afflicting Higgs boson physics at the infamous LHC wedge.
We present an analysis of the production and two-photon decay of the lightest CP-even Higgs boson of the Minimal Supersymmetric Standard Model (MSSM) at the Large Hadron Collider (LHC). A rather general model is considered, without supergravity constraints. All parameters of the model are taken into account, we especially study the dependence of the cross section on the squark masses, on the bilinear parameter $mu$ and the trilinear supersymmetry breaking parameter $A$. Non-zero values of these parameters lead to significant mixing in the squark sector, and, thus, affect the masses of Higgs bosons through radiative corrections, as well as their couplings to squarks. The cross section times the two-photon branching ratio of $h^0$ is of the order of 15--25~fb in much of the parameter space that remains after imposing the present experimental constraints on the parameters.
We calculate the cross section of Higgs boson pair production at a photon collider in the two Higgs doublet model. We focus on the scenario in which the lightest CP even Higgs boson ($h$) has the standard model like couplings to the gauge bosons. We take into account the one-loop correction to the $hhh$ coupling as well as additional one-loop diagrams due to charged Higgs bosons to the $gammagammato hh$ helicity amplitudes. It is found that the full cross section can be enhanced by both these effects to a considerable level. We discuss the impact of these corrections on the $hhh$ coupling measurement at the photon collider.
Inclusive Higgs boson pair production through the mechanism of gauge boson fusion e^{+} e^{-} -> V* V* -> h h + X (V=W,Z) in the general Two-Higgs-Doublet Model (2HDM), with h=h^0,H^0,A^0,H^{pm}, is analyzed at order alpha^4_{ew} in the linear colliders ILC and CLIC. This kind of processes is highly sensitive to the trilinear Higgs (3H) boson self-interactions and hence can be a true keystone in the reconstruction of the Higgs potential. For example, in the ILC at 1 TeV, the most favorable scenarios yield cross-sections up to roughly 1 pb, thus entailing 10^5 events per 100 fb^{-1} of integrated luminosity, whilst remaining fully consistent with the perturbativity and unitarity bounds on the 3H couplings, the electroweak precision data and the constraints from BR(b->sgamma). Comparing with other competing mechanisms, we conclude that the Higgs boson-pair events could be the dominant signature for Higgs-boson production in the TeV-class linear colliders for a wide region of the 2HDM parameter space, with no counterpart in the Minimal Supersymmetric Standard Model. Owing to the extremely clean environment of these colliders, inclusive 2H events should allow a comfortable tagging and might therefore open privileged new vistas into the structure of the Higgs potential.
We study the detectability of the stoponium in the di-Higgs decay mode at the photon-photon collider option of the International $e^+e^-$ Linear Collider (ILC), whose center-of-mass energy is planned to reach $sim 1$ TeV. We find that $5sigma$ detection of the di-Higgs decay mode is possible with the integrated electron-beam luminosity of $1 {rm ab}^{-1}$ if the signal cross section, $sigma(gamma gamma rightarrow sigma_{tilde{t}_1} rightarrow hh)$, of ${cal O}(0.1)$ fb is realized for the stoponium mass smaller than $sim$ 800 GeV at 1 TeV ILC. Such a value of the cross section can be realized in the minimal supersymmetric standard model (MSSM) with relatively large trilinear stop-stop-Higgs coupling constant. Implication of the stoponium cross section measurement for the MSSM stop sector is also discussed.
At the Large Hadron Collider (LHC), the CP-even Higgs bosons ($h^0$ and $H^0$) of the Minimal Supersymmetric Standard Model (MSSM) will be searched for mainly through their two-photon decay. We present a detailed analysis of the production and two-photon decay of the CP-even Higgs bosons of MSSM at the LHC by taking into account all the parameters of the model, especially the bilinear parameter $mu$ and the trilinear supersymmetry breaking parameter $A$. Non-zero values of these parameters lead to significant mixing in the squark sector, and, thus, affect the masses of Higgs bosons through radiative corrections, as well as their couplings to squarks. The dependence of the cross section for the production of Higgs, and its subsequent decay to two photons, on various parameters of the MSSM is described in detail. The cross section times the two-photon branching ratio of $h^0$ is of the order of 15--25~fb in much of the parameter space that remains after imposing the present experimental constraints on the parameters. For the $H^0$, the two-photon branching ratio is only significant if it is light. With a light $H^0$ the cross section times the branching ratio may be 200~fb or more.