Within the context of the Littlest Higgs model with T-parity, the heavy photon ($A_{H}$) is supposed to be an ideal dark matter (DM) candidate. One direct proof of validity of the model is to produce the heavy photon at collider. In this paper, we investigate the associated production of a photon with heavy photon pair at the planned international $e^ +e^ -$ linear collider (ILC), i.e., $ e^+ e^-\to A_{H}A_{H}γ$ and show the distributions of the transverse momenta of the photon. The numerical results indicate that the heavy photon production rate could reach several $fb$ at the low mass parameter space and the characteristic signal is a single high energetic photon and missing energy, carried by the heavy photons. All in all, it can be good chance to observe the heavy photon via this process with the high yearly luminosity of the ILC.
The littlest Higgs model is the most economical one among various little Higgs models. In the context of the littlest Higgs model, we study the process $e^{+}e^{-}\to e^{+}e^{-}H$ at the ILC and calculate the correction of the littlest Higgs model to the cross section of this process. The results show that, in the favorable parameter spaces preferred by the electroweak precision data, the value of the relative correction is in the range from a few percent to tens percent. In most case, the correction is large enough to reach the measurement precision of the ILC. Therefore, the correction of th…
In the littlest Higgs model with T-parity, we studied the contributions of the new particles to the top-quark pair production via $e^{+}e^{-}$ collision at the International Linear Collider. We calculated the top-quark pair production cross section and found this process can generate significantly relative correction. The result may be a sensitive probe of the littlest Higgs model with T-parity.
In the littlest Higgs model with T-parity, the new interactions between the mirror leptons and the Standard Model leptons can induce some lepton flavor violation (LFV) processes at loop level. We study the possibility of the ILC to probe the LFV production processes $e^+e^-(γγ)\rightarrow l_{i}\bar{l}_{j}$. Our results show that the rates of $γγ\rightarrow l_{i}\bar{l}_{j}$ can reach 1 fb in optimal cases after reasonable kinematical cuts, which implies that these processes may be observed at the ILC.
With high luminosity and energy at the ILC and clean SM backgrounds, the top-charm production at the ILC should have powerful potential to probe new physics. The littlest Higgs model with discrete symmetry named "T-parity"(LHT) is one of the most promising new physics models. In this paper, we study the FC processes $e^+e^-(γγ)\to t\bar{c}$ at the ILC in the LHT model. Our study shows that the LHT model can make a significant contribution to these processes. When the masses of mirror quarks become large, these two processes are accessible at the ILC. So the top-charm production at the ILC prov…
We study the top-quark pair production via polarized and unpolarized photon collisions at the International Linear Collider in the context of the littlest Higgs model with T-parity. We calculate the production cross section of the process $γγ\rightarrow t\bar{t}$ and find the effects can be more significant in the $- -$ polarized photon collision mode than in other collision modes, and the relative correction can be expected to reach about -1% in the favorable parameter space.
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…
In the littlest Higgs model with T-parity (LHT) the mirror quarks induce the special flavor structures and some new flavor-changing (FC) couplings which could greatly enhance the production rates of the FC processes. We in this paper study some bottom and anti-strange production processes in the LHT model at the International Linear Collider (ILC), i.e., $e^+e^-\rightarrow b\bar{s}$ and $γγ\rightarrow b\bar{s}$. The results show that the production rates of these processes are sizeable for the favorable values of the parameters. Therefore, it is quite possible to test the LHT model or make som…
In this work, the production processes of heavy neutral scalar and pseudo scalar associated with standard model gauge boson $Z_L$ at future $e^{+}e^{-}$ colliders (ILC and CLIC) are examined. The total and differential cross sections are calculated for the processes in the context of the littlest Higgs model. Also dependence of production processes to littlest Higgs model parameters in the range of compatibility with electroweak precision measurements and decays to lepton flavor violating final states are analyzed. We have found that both heavy scalar and pseudoscalar will be produced in $e^+e…
We study the possibility of using W pair production and leptonic decay of one of the W's at the ILC with polarized beams as a probe of the Littlest Higgs Model. We consider cross-sections, polarization fractions of the W's, leptonic decay energy and angular distributions, and left-right polarization asymmetry as probes of the model. With parameter values allowed by present experimental constraints detectable effects on these observables at typical ILC energies of 500 GeV and 800 GeV will be present. Beam polarization is further found to enhance the sensitivity.
The littlest Higgs model with T-parity (LHT) has new flavor-changing (FC) couplings with the Standard Model (SM) quarks, which do not suffer strong constraints from electroweak precision data. So these FC interactions may enhance the cross sections of some flavor-changing neutral-current (FCNC) processes. In this work, we study the FC top-charm associated productions via $e^{-}γ$ collision at the ILC. We find that the cross sections are sensitive to the mirror quark masses. With reasonable values of the parameters, the cross sections may reach the detectable level and provide useful informatio…
In the littlest Higgs model with T-parity (LHT) the mirror quarks induce the special flavor structures and some new flavor-changing (FC) couplings which could greatly enhance the production rates of the FC processes. We in this paper study some bottom and anti-strange production processes in the LHT model at the International Linear Collider (ILC), i.e., $e^+e^-\to b\bar{s}$ and $γγ\to b\bar{s}$. The results show that the production rates of these processes are sizeable for the favorable values of the parameters. Therefore, it is quite possible to test the LHT model or make some constrains on …
In the Littlest Higgs model with T-parity, the heavy photon ($A_{H}$) is supposed to be a possible dark matter (DM) candidate. A direct proof of validity of the model is to produce the heavy photon at accelerator. In this paper, we study the production rate of $ e^ + e^ - \to A_{H}A_{H}$ at the international $e^ + e^ -$ linear collider (ILC) in the Littlest Higgs model with T-parity and show the distributions of the transverse momenta of $A_{H}$. The numerical results indicate that the heavy photon production rate could reach the level of $10^{-1} fb$ at some parameter space, so it can be a go…
In the Littlest Higgs model with T-parity, we study production processes of new gauge bosons at the international linear collider (ILC). Through Monte Carlo simulations of the production processes, we show that the heavy gauge boson masses can be determined very accurately at the ILC for a representative parameter point of the model. From the simulation result, we also discuss the determination of other model parameters at the ILC.
The neutral gauge boson $B_H$ with the mass of hundreds GeV, is the lightest particle predicted by the littlest Higgs(LH) model, and such particle should be the first signal of the LH model at the planed ILC if it exists indeed. In this paper, we study some processes of the $B_H$ production associated with the fermion pair at the ILC, i.e., $γγ\to f\bar{f}B_{H}$. The studies show that the most promising processes to detect $B_H$ among $γγ\to f\bar{f}B_{H}$ are $γγ\to l'^+l'^-B_{H}(l'=e,μ)$, and they can produce the sufficient signals in most parameter space preferred by the electroweak precisi…
We examine the effects of the extended gauge sector of the Littlest Higgs model in high energy e+e- collisions. We find that the search reach in e+e- -> f fbar at a 500 GeV center-of-mass energy International Linear Collider covers essentially the entire parameter region where the Littlest Higgs model is relevant to the gauge hierarchy problem. In addition, we show that this channel provides an accurate determination of the fundamental model parameters, to the precision of a few percent, provided that the LHC measures the mass of the heavy neutral gauge field. Additionally, we show that the co…
We investigate a possibility of precision measurements for parameters of the Littlest Higgs model with T-parity at the International Linear Collider (ILC). The model predicts new gauge bosons which masses strongly depend on the vacuum expectation value that breaks a global symmetry of the model. Through Monte Carlo simulations of production processes of new gauge bosons, we show that these masses can be determined very accurately at the ILC for a representative parameter point of the model. From the simulation result, we also discuss the determination of other model parameters at the ILC.
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 $e^+e^- \to γ(Z)B_H$ 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 $e^+e^- \to γB_H$. Furthermore, there exist some decay modes for $B_H$ which can provide the typical signal and cl…
In the parameter space allowed by the electroweak precision measurement data, we consider the contributions of the new particles predicted by the littlest Higgs($LH$) model to the Higgs boson associated production with top quark pair in the future high energy linear $e^{+}e^{-}$ collider($ILC$). We find that the contributions mainly come from the new gauge bosons $Z_{H}$ and $B_{H}$. For reasonable values of the free parameters, the absolute value of the relative correction parameter $δσ/σ^{SM}$ can be significanly large, which might be observed in the future $ILC$ experiment with $\sqrt{S}=80…
The littlest Higgs model is the most economical little Higgs model. The observation of the new gauge bosons predicted by the littlest Higgs model could serve as a robust signature of the model. The ILC, with the high energy and luminosity, can open an ideal window to probe these new gauge bosons, specially, the lightest $B_H$. In the framework of the littlest Higgs model, we study a gauge boson $B_{H}$ production process $γγ\to W^{+}W^{-}B_H$. The study shows that the cross section of the process can vary in a wide range($10^{-1}-10^1$ fb) in most parameter spaces preferred by the electroweak …
Single production of the doubly charged scalars $Φ^{\pm\pm}$ via $eγ$, $ep$ and $pp$ collisions is studied in the context of the little Higgs$(LH)$ model. Our numerical results show that the new particles $Φ^{\pm\pm}$ can be abundantly produced and their possible signatures should be detected in future high energy linear $e^{+}e^{-}$ collider$(ILC)$. The cross section for single production of $Φ^{\pm\pm}$ at the $LHC$ is much smaller than that at the $ILC$ or the $THERA$.
The Higgs boson production processes $e^{+}e^{-}\to ZH$, $e^{+}e^{-}\to \bar{ν_{e}}ν_{e}H$, and $e^{+}e^{-}\to t\bar{t}H$ are very important for studying Higgs boson properties and further testing new physics beyond the standard model($SM$) in the high energy linear $e^{+}e^{-}$ collider($ILC$). We estimate the contributions of the littlest Higgs model with T-parity($LHT$ model) to these processes and find that the $LHT$ model can generate significantly corrections to the production cross sections of these processes. We expect the possible signals of the $LHT$ model can be detected via these p…
In the framework of the littlest Higgs($LH$) model, we consider the processes $e^{+}e^{-}\toν\barνH^{0}$ and $e^{+}e^{-}\to W^{*}W^{*}ν\barν\toν\barνt\bar{t}$, and calculate the contributions of new particles to the cross sections of these processes in the future high energy $e^{+}e^{-}$ collider($ILC$) with $\sqrt{S}=1TeV$. We find that, with reasonable values of the free parameters, the deviations of the cross sections for the processes $e^{+}e^{-}\toν\barνH^{0}$ from its $SM$ value might be comparable to the future $ILC$ measurement precision. The contributions of the light Higgs boson $H^0…
In the framework of the littlest Higgs model with T-parity (LHT), we study the contributions of the T-even and T-odd particles to the branching ratio R_b. We find that the precision data of R_b can give strong constraints on the masses of T-odd fermions.
Flavor changing neutral current processes are studied in the littlest Higgs model with T-parity. It is found that the logarithmic divergence reported earlier in Z boson flavor changing processes is exactly canceled by contributions from additional interaction terms of heavy fermions and the Z boson. Phenomenological impact on the K --> pi nu nu_bar processes is discussed.
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 $γγ$ and $eγ$ collision will open a wider window to probe $B_H$. In this paper, we study the new gauge boson $B_{H}$ production processes $e^{-}γ\to e^{-}γB_{H}$ and $e^{-}γ\to e^{-}Z B_{H}$ at the ILC. Our results show that the production cross section of the process $e^{-}γ\to e^{-}Z B_{H}$ is less than one fb in the most parameter spaces w…
We present the results of an extensive analysis of lepton flavour violating decays in the Littlest Higgs model with T-parity (LHT). As lepton flavour violation is highly suppressed in the Standard Model by small neutrino masses, the LHT effects turn out to be naturally huge and could be seen in the near future experiments.
We analyse hadronically quiet trilepton signatures in the T-parity conserving Littlest Higgs model and in R-parity conserving supersymmetry at the Large Hadron Collider. We identify the regions of the parameter space where such signals can reveal the presence of these new physics models above the Standard Model background and distinguish them from each other, even in a situation when the mass spectrum of the Littlest Higgs model resembles the supersymmetric pattern.
Based on calculating the contributions of the littlest Higgs model with T-parity (called $LHT$ model) to the anomalous top coupling $tqγ$ ($q=u$ or $c$), we consider single top production via the t-channel partonic process $eq\to et$ at $ep$ collision. Our numerical results show that the production cross section in the $LHT$ model can be significantly enhanced relative to that in the standard model.
The littlest Higgs model with T-parity, which is called $LHT$ model, predicts the existence of the new particles, such as heavy top quark, heavy gauge bosons, and mirror fermions. We calculate the one-loop contributions of these new particles to the top quark chromomagnetic dipole moment $(CMDM)$ $ΔK$. We find that the contribution of the $LHT$ model is one order of magnitude smaller than the standard model prediction value.
In this paper we consider the effects of the T-parity violating anomalous Wess-Zumino-Witten-Term in the Littlest Higgs model. Apart from tree level processes, the loop induced decays of the heavy mirror particles into light standard model fermions lead to a new and rich phenomenology in particular at breaking scales f below 1 TeV. Various processes are calculated and their signatures at present and future colliders are discussed. As a byproduct we find an alternative production mechanism for the Higgs boson.
The Littlest Higgs Model with T parity (LHT) is an interesting alternative model for New Physics at the TeV scale. Although Flavour Physics was not the reason for creating the LHT model, significant effects (such as large CP violation where not predicted by the SM) can be created without violating existing experimental bounds. We study the B-, K- and especially the D-sector.
Motivated by the search for flavor-changing neutral current (FCNC) top quark decays at the LHC, we calculate rare Higgs three body decay $H\rightarrow Wbc$ induced by top-Higgs FCNC coupling in the littlest Higgs model with T-parity(LHT). We find that the branching ratios of $H\rightarrow Wbc$ in the LHT model can reach $\mathcal O(10^{-7})$ in the allowed parameter space.
Little Higgs models offer an interesting approach to weakly coupled electroweak symmetry breaking without fine tuning. The original little Higgs models were plagued by strong constraints from electroweak precision data which required a fine tuning to be reintroduced. An economical solution to this problem is to introduce a discrete symmetry (analogous to R-parity of SUSY) called T-parity. T-parity not only eliminates most constraints from electroweak precision data, but it also leads to a promising dark matter candidate. In this paper we investigate the dark matter candidate in the littlest Hi…
In this work, we investigate the one-loop QCD correction to top pair production in the littlest Higgs model with T-parity at the LHC. We calculate the relative correction of the top pair production cross section and top-antitop spin correlation at the LHC for $\sqrt{s}=8,14$ TeV. We find that the relative corrections of top pair production cross section can reach about $-0.35\%$, and the top-antitop spin correlation can reach $1.7\%$($2\%$) at the 8(14) TeV LHC in the favorable parameter space.
Littlest Higgs model with T-parity predicts the existence of the neutral, weakly interacting, new gauge boson $B_{H}$, which can be seen as an attractive dark matter candidate. We study production of the new gauge boson $B_{H}$ via $eγ$ and $ep$ collisions. We find that $B_{H}$ can be abundantly produced via the subprocesses $e^{-}γ\to L^{-}B_{H}$ and $γq\to B_{H}Q$, which might give rise to characteristic signals. Some discussions about the $SM$ backgrounds for this kind of signals are also given.
In the littlest Higgs model with T-parity (LHT), we study the $t$-channel single top production in association with a Higgs boson at 8 and 14 TeV LHC. We find that the cross section can be enhanced obviously in this model compared to the Standard Model. By performing a simple parton-level simulation through $pp\rightarrow t(\rightarrow \ell^{+}νb)h(\rightarrow b\bar{b})j$ at 14 TeV LHC, we find that the observability of the signal is promising in the favorable parameter space.
In the littlest Higgs model with T-parity (LHT), the mirror quarks have flavor structures and will contribute to the top quark flavor changing neutral current. In this work, we perform an extensive investigation of the top quark rare three-body decays $t\to cVV (V=γ,Z,g)$ and $t\to cf\bar{f} (f=b,τ,μ,e)$ at one-loop level. Our results show that the branching ratios of $t\to cgg$ and $t\to cb\bar{b}$ could reach $\mathcal {O}(10^{-3})$ in the favorite parameter space of the littlest Higgs model with T-parity, which implies that these decays may be detectable at the LHC or ILC, while for the oth…
In the littlest Higgs model with T-parity, we study associated production of a Higgs and a single top quark at the 14 TeV LHC. We focus on the Higgs to two photons decay and the semileptonic top decay channel. By performing a fast detector simulation, we find that the $thj$ search in the selected channel can excluded the top partner mass $m_{T_{+}}$ up to 805 (857) GeV for case A (case B) at $2σ$ confidence level at 14 TeV LHC with the integrated luminosity $L= 3 \rm ab^{-1}$.
Little Higgs models are an interesting alternative to explain electroweak symmetry breaking without fine-tuning. Supplemented with a discrete symmetry (T-parity) constraints from electroweak precision data are naturally evaded and also a viable dark matter candidate is obtained. T-parity implies the existence of new (mirror) fermions in addition to the heavy gauge bosons of the little Higgs models. In this paper we consider the effects of the mirror fermions on the phenomenology of the littlest Higgs model with T-parity at the LHC. We study the most promising production channels and decay chai…
We first study the hadronic lepton flavor violating tau decays within the littlest Higgs model with T-parity (including one or two pseudoscalars, or a vector resonance). We consider the case where only T-odd particles and partner fermions contribute, and also its extension including Majorana neutrinos coming from an inverse seesaw. In both cases our mean values lie only one order of magnitude below current upper limits, strengthening the case of searching for these decays in the quest for new physics.
We show that a precise measurement of the single-top production cross section at the Tevatron and the LHC can strongly constrain the model parameters of the Littlest Higgs model with T-parity. A reduction in the single-top production rate from the Standard Model prediction implies new physics phenomena generated by the heavy T-parity partners of the top quark. We show that the degree of polarization of the top quark produced from the decay of its heavy T-odd partner ($T_{-}$) can be utilized to determine the new physics energy scale, and the mass of $T_{-}$ can be measured from the missing tra…
One of the important features of the littlest Higgs model with T-parity, called the $LHT$ model, is that it introduces the mirror fermions, which are the T-parity partners of the standard model fermions. In this paper, we discuss production of the mirror quark associated with mirror neutrino via $eγ$ and $ep$ collisions. We find that, in wide range of the parameter space, the mirror quark can be copiously produced at the International $e^{+}e^{-}$ Linear Collider $(ILC)$ and $ep$ collider $(THERA)$ experiments. The production rates of certain signal events, which are related the main two-body …
We investigate a possibility to measure parameters of the Littlest Higgs model with T-parity at the ILC with sqrt(s) = 500 GeV. The model predicts new gauge bosons (AH, ZH, and WH), among which the heavy photon (AH) is a candidate for dark matter. Through Monte Carlo simulations of the process of e+ e- -> AH ZH, we show that the masses can be determined with accuracies of 16.2% for m_AH and 4.3% for m_ZH. In additionally, the vacuum expectation value can be determined with accuracies of 4.3%.
We show that the inverse see-saw is the most natural way of implementing neutrino masses in the Littlest Higgs model with T-parity. The three extra quasi-Dirac neutrinos are needed to cancel the quadratically divergent contributions of the mirror leptons to the Higgs mass. If the T-parity of the heavy neutrino singlets is chosen to be even, their contributions to lepton flavor violating transitions are one-loop finite. The most stringent limits on this scenario result from the non-observation of these transitions. Constraints on neutrino mixing imply an upper bound on the mass of the T-odd mir…
The Little Higgs model with T-parity (LHT) belongs to the non-minimal flavour violating model. This model has new sources of flavour and CP violation both in quark and leptonic sectors. These new sources of flavour violation originates by the interaction of Standard Model (SM) fermions with heavy gauge bosons and heavy (or mirror) fermions. In this work we will present the impact of the new flavour structure of T-parity models on flavour violations in leptonic sector.
We consider the Littlest Higgs Model with T-parity (LHT), in the parameter region where a heavy neutrino is the lightest T-odd particle (LTP). Having emphasized that this corresponds to a sizable region in the parameter space of the theory, we show that both the Cryogenic Dark Matter Search (CDMS) and Xenon10 experiments disallow the entire region where the masses of the new particles in LHT can lie within several TeV. Therefore, any observation of the signals of a heavy neutrino LTP is likely to seriously reopen the issue of cold dark matter in the universe.
We analyze the rare and flavor changing decay of the top quark into a charm quark and a gauge boson in the littlest Higgs model with T-parity (LHT). We calculate the one-loop level contributions from the T-parity odd mirror quarks and gauge bosons. We find that the decay $t\to c V, (V=g,γ,Z)$ in the LHT model can be significantly enhanced relative to those in the Standard Model. Our numerical results show that the top quark FCNC decay can be as large as $Br(t\to cg)\sim 10^{-2}$, $Br(t\to cZ)\sim 10^{-5}$ and $Br(t\to cγ)\sim 10^{-7}$ in the favorite parameter space in the LHT model.
The results of an extensive flavour physics analysis in the Littlest Higgs model with T-parity are presented. In particular, mixing and CP-violation in K^0 and B^0_{d,s} systems have been studied. Several scenarios defined by the values of mirror quark masses and the parameters of the new flavour mixing matrix V_Hd have been considered. A very interesting scenario is identified, where the well-known kaon constraints are satisfied, the sin(2beta) and Delta M_s issues are improved w.r.t the Standard Model and visible effects could be soon found in A_SL^s and S_{psi phi}.
Inspired by the recent CMS $h \to μτ$ excess, we calculate the lepton flavor violating Higgs decay $h \to μτ$ in the littlest Higgs model with T-parity (LHT). Under the constraints of $\ell_i \to \ell_j γ$, $Z \to \ell_i \bar{\ell}_j$ and Higgs data, we find that the branching ratio of $h \to μτ$ can maximally reach $\mathcal O(10^{-4})$. We also investigate the correlation between $h \to μτ$, $τ\to μγ$ and $Z \to μτ$, which can be used to test LHT model at future $e^+e^-$ colliders.
The littlest $Higgs$ model with T-parity (called the $LHT$ model) predicts the existence of the T-odd leptons, which can generate contributions to some leptonic processes at the one-loop level. We calculate their contributions to the leptonic $Z$ decay processes $Z\to l\bar{l'}$, $Z\to l\bar{l}$, and $Z\rightarro ν\barν$. We find that the T-odd leptons can give significant contributions to the branching ratios of these decay processes in most of the parameter space. The experimental measurement values might generate constraints on the free parameters of the $LHT$ model.
Motivated by the first experimental evidence of meson oscillations in the D system, we study D^0 - \bar D^0 mixing in the Littlest Higgs model with T-parity, we investigate its role in constraining the model parameters and its impact on the most interesting flavour observables. We find that the experimental data are potentially strongly constraining but at present limited by large theoretical uncertainties in the long-distance Standard Model contribution to D^0 - \bar D^0 mixing.
Flavour changing neutral current processes, being strongly suppressed in the Standard Model (SM), provide a unique window to new physics at scales much above the electroweak scale. Here, we summarize the recent progress in flavour physics studies of the Littlest Higgs model with T-parity, both in the quark and lepton sector. Particular emphasis is put on various correlations that could distinguish this model from other extensions of the SM.
We recalculate the leading one-loop contributions to mu > e gamma and mu -> eee in the Littlest Higgs model with T-parity, recovering previous results for the former. When all the Goldstone interactions are taken into account, the latter is also ultraviolet finite. The present experimental limits on these processes require a somewhat heavy effective scale ~2.5 TeV, or the flavour alignment of the Yukawa couplings of light and heavy leptons at the ~10% level, or the splitting of heavy lepton masses to a similar precision. Present limits on tau decays set no bounds on the corresponding parameter…
In this work we calculate the leading electroweak (EW) corrections to the anomalous $gt\bar{t}$ coupling in the Littlest Higgs model with T-parity (LHT), by applying the Goldstone boson equivalence theorem. In the LHT model, such electroweak corrections arise from the loop diagrams of heavy fermions and the ``would-be'' Goldstone bosons. We further examine the EW corrections in the top quark pair production via the quark annihilation process at the LHC. The negative EW corrections in the Standard Model are partially canceled by the positive EW corrections from the loops of the new heavy partic…
In this work, we investigate the Higgs-boson production processes $e^{+}e^{-}\rightarrow ZH$, $e^{+}e^{-}\rightarrow ν_{e}\bar{ν_{e}}H$ and $e^{+}e^{-}\rightarrow e^{+}e^{-}H$ in the littlest Higgs model with T-parity. We present the production cross sections, the relative corrections and some distributions of the final states. In the allowed parameter space, we find that the relative corrections of the three production channels are negative, the relative correction of the $ZH$ production can reach $-7.5\%$ and the relative corrections of the $ν_{e}\bar{ν_{e}}H$ and $e^{+}e^{-}H$ production ca…
A study of the effective tbW vertex is done in the littlest Higgs model with T parity that includes the one loop induced weak dipole coefficient f_{2R}. The top's width, the W-boson helicity in the t-> bW^+ decay as well as the t-channel and the s-channel modes of single top quark production at the LHC are then obtained for the tbW coupling. Our calculation is done in the Feynman-'t Hooft gauge, and we provide details of the analysis, like exact formulas (to all orders of the expansion variable v/f) of masses and mixing angles of all the particles involved. Also, a complete and exact diagonali…
Higgs boson productions at the LHC will serve as a sensitive probe of various little Higgs models. In this work we comparatively study two littlest Higgs models with different T-parity constructions through examining their effects in three production processes of the Higgs boson at the LHC, namely the productions of a single Higgs, a Higgs-pair, as well as a Higgs boson associated with a pair of top and anti-top quarks. The two models are characterized by predicting a top partner canceling the Higgs mass quadratic divergence contributed by the top quark with even and odd T-parity, respectively…
In the framework of the littlest Higgs model with T-parity (LHT), we study the production processes of T-even (T_+) and T-odd (T_-) partners of the top quark at the Large Hadron Collider (LHC). We show that the signal events can be distinguished from the standard-model backgrounds, and that information about mass and mixing parameters of the top partners can be measured with relatively good accuracies. With the measurements of these parameters, we show that a non-trivial test of the LHT can be performed. We also discuss a possibility to reconstruct the thermal relic density of the lightest T-o…
In this paper we discuss the consequences of including a new heavy right-handed neutrino singlet $N_R$ in the littlest Higgs model. This new state is not connected with the light neutrinos {\it via} the seesaw mechanism. A very interesting property of this extended model is the full coupling of the new neutral gauge boson $A_H$ to $N_R$, giving large total cross sections and suggesting a wide range of experimental search for the $N_R$ at the p p collider CERN-LHC and future electron-positron collider ILC.
In the framework of the littlest Higgs Model with T-parity, we discuss the top partner production at future $e^{+}e^{-}$ collider. We calculate the cross sections of the top partner production processes and associated production processes of Higgs and top partner under current constraints. Then, we investigate the observability of the T-odd top partner pair production through the process $e^{+}e^{-}\rightarrow T_{-}\bar{T}_{-}\rightarrow t\bar{t}A_{H}A_{H}$ in the $t\bar{t}$ di-lepton channel for two T-odd top partner mass $m_{T_{-}}$=603(708) GeV at $\sqrt{s}$=1.5 TeV. We analyze the signal s…
