No Arabic abstract
The new lightest gauge boson $B_H$ with mass of a few hundred GeV is predicted in the littlest Higgs model. $B_H$ should be accessible in the planed ILC and the observation of such particle can strongly support the littlest Higgs model. The realization of $gammagamma$ and $egamma$ collision will open a wider window to probe $B_H$. In this paper, we study the new gauge boson $B_{H}$ production processes $e^{-}gammato e^{-}gamma B_{H}$ and $e^{-}gammato e^{-}Z B_{H}$ at the ILC. Our results show that the production cross section of the process $e^{-}gammato e^{-}Z B_{H}$ is less than one fb in the most parameter spaces while the production cross section of the process $e^{-}gammato e^{-}gamma B_{H}$ can reach the level of tens fb and even hundreds of fb in the sizable parameter spaces allowed by the electroweak precision data. With the high luminosity, the sufficient typical signals could be produced, specially via $e^{-}gammato e^{-}gamma B_{H}$. Because the final electron and photon beams can be easily identified and the signal can be easily distinguished from the background produced by $Z$ and $H$ decaying, $B_H$ should be detectable via $egamma$ collision at the ILC. Therefore, the processes $e^{-}gammato e^{-}gamma B_{H}$ and $e^{-}gammato e^{-}Z B_{H}$ provide a useful way to detect $B_{H}$ and test the littlest Higgs model.
With the high energy and luminosity, the planned ILC has the considerable capability to probe the new heavy particles predicted by the new physics models. In this paper, we study the potential to discover the lightest new gauge boson $B_{H}$ of the littlest Higgs model via the processes $e^+e^- to gamma (Z)B_H$ at the ILC. The results show that the production rates of these two processes are large enough to detect $B_H$ in a wide range of the parameter space, specially for the process $e^+e^- to gamma B_H$. Furthermore, there exist some decay modes for $B_H$ which can provide the typical signal and clean background. Therefore, the new gauge boson $B_H$ should be observable via these production processes with the running of the ILC if it exists indeed.
The littlest Higgs model is the most economical one among various little Higgs models. In the context of the littlest Higgs(LH) model, we study the process $e^{-}gammato u_{e}W^{-}H$ and calculate the contributions of the LH model to the cross section of this process. The results show that, in most of parameter spaces preferred by the electroweak precision data, the value of the relative correction is larger than 10%. Such correction to the process $e^{-}gammato u_{e}W^{-}H$ is large enough to be detected via $e^{-}gamma$ collisions in the future high energy linear $e^{+}e^{-}$ collider($LC$) experiment with the c.m energy $sqrt{s}$=500 GeV and a yearly integrated luminosity $pounds=100fb^{-1}$, which will give an ideal way to test the model.
The physics prospect at future linear $e^{+}e^{-}$ colliders for the study of the Higgs triple self-coupling via the process of $e^{+}e^{-}to ZHH$ is investigated. In this paper, we calculate the contribution of the new particles predicted by the littlest Higgs model to the cross sections of this process in the future high energy $e^{+}e^{-}$ collider($ILC$). The results show that, in the favorable parameter spaces preferred by the electroweak precision, the deviation of the total cross sections from its $SM$ value varies from a few percent to tens percent, which may be detected at the future $ILC$ experiments with $sqrt{s}$=500GeV.
In the context of the littlest Higgs$(LH)$ model, we study the process $ e^{+}e^{-}to tbar{t}$. We find that the new gauge bosons $Z_{H}$ and $B_{H}$ can produce significant correction effects on this process, which can be further enhanced by the suitably polarized beams. In most of the parameter space preferred by the electroweak precision data, the absolute value of the relative correction parameter $R_{B_{H}}$ is larger than 5%. As long as $1TeVleq M_{Z_{H}}leq 1.5TeV$ and $0.3leq cleq 0.5,$ the absolute value of the relative correction parameter $R_{Z_{H}}$ is larger than 5%. With reasonable values of the parameters of the $LH$ model, the possible signals of the new gauge bosons $B_{H}$ and $Z_{H}$ can be detected via the process $ e^{+}e^{-} to tbar{t}$ in the future $LC$ experiments with the c.m. energy $sqrt{S}=800GeV$. $B_{H}$ exchange and $Z_{H}$ exchange can generate significantly corrections to the forward-backward asymmetry $A_{FB}(tbar{t})$ only in small part of the parameter space.
Higgs boson production in association with a photon ($H$+$gamma$) offers a promising channel to test the Higgs boson to photon coupling at various energy scales. Its potential sensitivity to anomalous couplings of the Higgs boson has not been explored with the proton-proton collision data. In this paper, we reinterpret the latest ATLAS $H$+$gamma$ resonance search results within the Standard Model effective field theory (EFT) framework, using 36.1 fb$^{-1}$ of proton-proton collision data recorded with the ATLAS detector at $sqrt{s}=13$ TeV. Constraints on the Wilson coefficients of dimension-six EFT operators related to the Higgs boson to photon coupling are provided for the first time in the $H$+$gamma$ final state at the LHC.