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Probing New Physics using top quark polarization in the e+e- -> t \bar{t} process at future Linear Colliders
http://ilcdoc.linearcollider.org/record/60849
We investigate the sensitivity to new physics of the process e+e- -> t bar{t} when the top polarization is analyzed using leptonic final states e+e- -> t \bar{t} -> l+l- b \bar{b} nu_l \bar{nu}_l. We first show that the kinematical reconstruction of the complete kinematics is experimentally tractable for this process. Then we apply the matrix element method to study the sensitivity to the Vt\bar{t} coupling (V being a vector gauge boson), at the tree level and in the narrow width approximation. Assuming the ILC baseline configuration, sqrt{S}=500 GeV, and a luminosity of 500 fb^{-1}, we conclude that this optimal analysis allows to determine simultaneously the ten form factors that parameterize the Vt\bar{t} coupling, below the percent level. We also discuss the effects of the next leading order (NLO) electroweak corrections using the GRACE program with polarized beams. It is found that the NLO corrections to different beam polarization lead to significantly different patterns of contributions.Khiem, P HTue, 17 Mar 2015 19:22:02 GMThttp://ilcdoc.linearcollider.org/record/608492015The Dark Penguin Shines Light at Colliders
http://ilcdoc.linearcollider.org/record/60848
Collider experiments are one of the most promising ways to constrain Dark Matter (DM) interactions. For several types of DM-Standard Model couplings, a meaningful interpretation of the results requires to go beyond effective field theory, considering simplified models with light mediators. This is especially important in the case of loop-mediated interactions. In this paper we perform the first simplified model study of the magnetic dipole interacting DM, by including the one-loop momentum-dependent form factors that mediate the coupling -- given by the Dark Penguin -- in collider processes. We compute bounds from the monojet, monophoton, and diphoton searches at the $8$ and $14$ TeV LHC, and compare the results to those of direct and indirect detection experiments. Future searches at the $100$ TeV hadron collider and at the ILC are also addressed. We find that the optimal search strategy requires loose cuts on the missing transverse energy, to capture the enhancement of the form factors near the threshold for on-shell production of the mediators. We consider both minimal models and models where an additional state beyond the DM is accessible. In the latter case, under the assumption of anarchic flavor structure in the dark sector, the LHC monophoton and diphoton searches will be able to set much stronger bounds than in the minimal scenario. A determination of the mass of the heavier dark fermion might be feasible using the $M_{T2}$ variable. In addition, if the Dark Penguin flavor structure is almost aligned with that of the DM mass, a displaced signal from the decay of the heavier dark fermion into the DM and photon can be observed. This allows us to set constraints on the mixings and couplings of the model from an existing search for non-pointing photons.Primulando, ReinardTue, 17 Mar 2015 19:22:02 GMThttp://ilcdoc.linearcollider.org/record/608482015Searches for dark matter signals in simplified models at future hadron colliders
http://ilcdoc.linearcollider.org/record/60806
We study the prospect of dark matter (DM) searches in the monojet channel at future $pp$ colliders with center-of-mass energies of 33, 50, and 100~TeV. We consider a class of simplified models in which a vector boson connecting DM particles to quarks is introduced. Comparing with studies in the effective field theory, the present framework gives more reasonable production rates and kinematics of the DM signatures. We estimate the sensitivities of future colliders with an integrated luminosity of 3 $ab^{-1}$ to the DM-induced monojet signature and show the parameter space that can be explored. The constraints from direct and indirect DM detection experiments are compared with the future collider sensitivities. We find that the future collider detection will be much more sensitive than the indirect detection for the vector interaction, and have better sensitivities than those of the direct detection by several orders of magnitude for the axial vector interaction.Xiang, Qian-FeiWed, 11 Mar 2015 19:10:40 GMThttp://ilcdoc.linearcollider.org/record/608062015Off-shell effects in Higgs processes at a linear collider and implications for the LHC
http://ilcdoc.linearcollider.org/record/60767
The importance of off-shell contributions is discussed for $H\to VV^{(*)}$ with $V\in\{Z,W\}$ for large invariant masses $m_{VV}$ involving a standard model (SM)-like Higgs boson with $m_H=125$GeV at a linear collider (LC). Both dominant production processes $e^+e^-\to ZH\to ZVV^{(*)}$ and $e^+e^-\to\nu\bar\nu H\to\nu\bar\nu VV^{(*)}$ are taken into account, and the signal processes are compared with background yielding the same final state. The relative size of the off-shell contributions is strongly dependent on the centre-of-mass energy. These contributions can have an important impact on the determination of cross sections and branching ratios. However, the combination of on- and off-shell contributions can also be utilised to lift degeneracies allowing to test higher-dimensional operators, unitarity and light and heavy Higgs interferences in extended Higgs sectors. The latter is demonstrated in the context of a 2-Higgs-Doublet model. Where relevant, the impact of these aspects for physics at the Large Hadron Collider (LHC) is discussed. The importance of a precise measurement of the Higgs mass for on-shell contributions in $H\to VV^{(*)}$ is emphasized. A particular focus is put on methods for extracting the Higgs width at a LC. Off-shell contributions are shown to have a negligible impact on the width determination at low $\sqrt{s}$ when applying the $Z$ recoil method to extract branching ratios in combination with an appropriate determination of a partial width. On the other hand, off-shell contributions can be exploited to constrain the Higgs width in a similar fashion as in recent analyses at the LHC. It is demonstrated that this approach, besides relying heavily on theoretical assumptions, is affected by the negative interference of Higgs and background contributions that may limit the sensitivity that is achievable with the highest foreseeable statistics at the LHC and a LC.Liebler, StefanMon, 02 Mar 2015 18:53:53 GMThttp://ilcdoc.linearcollider.org/record/607672015Fingerprinting the extended Higgs sector using one-loop corrected Higgs boson couplings and future precision measurements
http://ilcdoc.linearcollider.org/record/60750
We calculate radiative corrections to a full set of coupling constants for the 125 GeV Higgs boson at the one-loop level in two Higgs doublet models with four types of Yukawa interaction under the softly-broken discrete $Z_2$ symmetry. The renormalization calculations are performed in the on-shell scheme, in which the gauge dependence in the mixing parameter which appears in the previous calculation is consistently avoided. We first show the details of our renormalizaton scheme, and present the complete set of the analytic formulae of the renormalized couplings. We then numerically demonstrate how the inner parameters of the model can be extracted by the future precision measurements of these couplings at the high luminosity LHC and the International Linear Collider.Kanemura, ShinyaFri, 27 Feb 2015 18:48:45 GMThttp://ilcdoc.linearcollider.org/record/607502015Multi-Higgs models. Perspectives for identification of wide set of models in future experiments at colliders in the SM-like situation
http://ilcdoc.linearcollider.org/record/60745
Higgs mechanism of EWSB can be realized in both well known minimal model and with more complex non-minimal Higgs models. These non-minimal models contain new Higgs bosons -- neutral $h_a$ and charged $H_b^\pm$. Necessary step in the discovery of such model is observation of these additional Higgses. We discuss the potential of such researches at modern and future colliders in the light of recent LHC results, for wide set of models, including 2HDM as a simplest example. Our conclusion is rather pessimistic. Discovery of new neutral Higgs boson at LHC is a very difficult task. Some windows to find them appear at accidentally favorable parameters of the theory. The regular way in the detection of these models is the study of processes with production of charged Higgs bosons (better, at Linear Collider).Ginzburg, I FThu, 26 Feb 2015 18:47:03 GMThttp://ilcdoc.linearcollider.org/record/607452015PeV Scale Right Handed Neutrino Dark Matter in $S_4$ Flavor Symmetric extra U(1) model
http://ilcdoc.linearcollider.org/record/60744
Recent observation of high energy neutrino in IceCube experiment suggests existence of superheavy dark matter beyond PeV. We identify the parent particles of neutrino as two degenerated right handed neutrinos, assuming the dark matter is the heaviest right handed neutrino. The $O(V_{cb})\sim O(10^{-2})$ flavor symmetry breaking accounts for the $O(10^{-4})$ mass degeneracy of right handed neutrinos which is a sizable scale to explain the successful resonant leptogenesis at the PeV scale. At the same time, non-thermal production of the heaviest right handed neutrino gives the right amount of dark matter for $T_{RH}\sim 10$PeV. The footprint of flavor symmetry is left in degenerated mass spectra of extra Higgs multiplet and colored Higgs multiplet which may be testable for LHC or future colliders.Daikoku, YasuhiroThu, 26 Feb 2015 18:47:03 GMThttp://ilcdoc.linearcollider.org/record/607442015A Quartz Cherenkov Detector for Compton-Polarimetry at Future e+e- Colliders
http://ilcdoc.linearcollider.org/record/60743
Precision polarimetry is essential for future e+ e- colliders and requires Compton polarimeters designed for negligible statistical uncertainties. In this paper, we discuss the design and construction of a quartz Cherenkov detector for such Compton polarimeters. The detector concept has been developed with regard to the main systematic uncertainties of the polarisation measurements, namely the linearity of the detector response and detector alignment. Simulation studies presented here imply that the light yield reachable by using quartz as Cherenkov medium allows to resolve in the Cherenkov photon spectra individual peaks corresponding to different numbers of Compton electrons. The benefits of the application of a detector with such single-peak resolution to the polarisation measurement are shown for the example of the upstream polarimeters foreseen at the International Linear Collider. Results of a first testbeam campaign with a four-channel prototype confirming simulation predictions for single electrons are presented.List, JennyThu, 26 Feb 2015 18:47:01 GMThttp://ilcdoc.linearcollider.org/record/607432015Sources of Charged Higgs Pair Through Double or Triple Higgs Production in Two Higgs Doublet Model Type II at Linear Colliders
http://ilcdoc.linearcollider.org/record/60712
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 2HDM may offer a clue to disentangle hints of physics beyond the Standard Model (SM) specially at linear colliders. By computing the three Higgs final state production cross-sections at the leading order allow a first insight into the Higgs potential and found several order of magnitude ($\sim 10^{4}$) enhancement in 2HDM than Minimal Supersymmetric Model (MSSM). While the traditional double charged Higgs production cross-section lie in the same order ($\sim 20 $ fb) of magnitude in both 2HDM and MSSM. Due to the extremely clean environment of linear collider, even though with less cross-section and corresponding less decay rate of triple Higgs compare to double Higgs can be used to identify having final state $\mu^{+}\mu^{-}\rightarrow H^{-}H^{+}H^{0} \rightarrow \tau\tau\nu\nu b\bar{b}$ by applying b-tagging. We also compare triple Higgs and double Higgs final states production cross-section in $\mu^+\mu^-$ collider with the $e^+e^-$ linear collider operating at $\sqrt s$ = 1.5 TeV and find no sizable difference.Ahmed, IjazTue, 24 Feb 2015 18:43:21 GMThttp://ilcdoc.linearcollider.org/record/607122015Testing sterile neutrino extensions of the Standard Model at future lepton colliders
http://ilcdoc.linearcollider.org/record/60711
Extending the Standard Model (SM) with sterile ('right-handed') neutrinos is one of the best motivated ways to account for the observed neutrino masses. We discuss the expected sensitivity of future lepton collider experiments for probing such extensions. An interesting testable scenario is given by 'symmetry protected seesaw models', which theoretically allow for sterile neutrino masses around the electroweak scale with up to order one mixings with the light (SM) neutrinos. In addition to indirect tests, e.g. via electroweak precision observables, sterile neutrinos with masses around the electroweak scale can also be probed by direct searches, e.g. via sterile neutrino decays at the Z pole, deviations from the SM cross section for four lepton final states at and beyond the WW threshold and via Higgs boson decays. We study the present bounds on sterile neutrino properties from LEP and LHC as well as the expected sensitivities of possible future lepton colliders such as ILC, CEPC and FCC-ee (TLEP).Antusch, StefanMon, 23 Feb 2015 18:41:38 GMThttp://ilcdoc.linearcollider.org/record/607112015Supergravity gauge theories strike back: There is no crisis for SUSY but a new collider may be required for discovery
http://ilcdoc.linearcollider.org/record/60644
More than 30 years ago, Arnowitt-Chamseddine-Nath (ACN) and others established the compelling framework of supergravity gauge theories (SUGRA) as a picture for the next step in beyond the Standard Model physics. We review the current SUGRA scenario in light of recent data from LHC8 collider searches and the Higgs boson discovery. While many SUSY and non-SUSY scenarios are highly disfavored or even excluded by LHC, the essential SUGRA scenario remains intact and as compelling as ever. For naturalness, some non-universality between matter and Higgs sector soft terms is required along with substantial trilinear soft terms. SUSY models with radiatively-driven naturalness (RNS) are found with high scale fine-tuning at a modest ~10%. In this case, natural SUSY might be discovered at LHC13 but could also easily elude sparticle search endeavors. A linear e^+e^- collider with \sqrt{s}>2m(higgsino) is needed to provide the definitive search for the required light higgsino states which are the hallmark of natural SUSY. In the most conservative scenario, we advocate inclusion of a Peccei-Quinn sector so that dark matter is composed of a WIMP/axion admixture i.e. two dark matter particles.Baer, HowardTue, 17 Feb 2015 18:30:40 GMThttp://ilcdoc.linearcollider.org/record/606442015Majorana Neutrino and $W_{R}$ at TeV scale $ep$ Colliders
http://ilcdoc.linearcollider.org/record/60623
Production of heavy Majorana neutrino $N_{e}$ predicted by left-right symmetric extension of the Standard Model at future {\normalsize TeV} scale $ep$ colliders have been considered. In order to estimate potential of $ep$ colliders for $N_{e}$ search we consider back-groundless process $e^{-}p\rightarrow e^{+}X$ which is consequence of Majorana nature of $N_{e}$. It is shown that {\normalsize linac-LHC} and {\normalsize linac-FCC} based $ep$ colliders will cover much wider regions of $N_{e}$ and $W_{R}$ masses than corresponding linear electron-positron colliders.Kaya, UMon, 16 Feb 2015 18:28:51 GMThttp://ilcdoc.linearcollider.org/record/606232015Footprints of Supersymmetry on Higgs Decay
http://ilcdoc.linearcollider.org/record/60622
Motivated by future collider proposals that aim to measure the Higgs properties precisely, we study the partial decay widths of the lightest Higgs boson in the minimal supersymmetric standard model with an emphasis on the parameter region where all superparticles and heavy Higgs bosons are not accessible at the LHC. Taking account of phenomenological constraints such as the Higgs mass, flavor constraints, vacuum stability, and perturbativity of coupling constants up to the grand unification scale, we discuss how large the deviations of the partial decay widths from the standard model predictions can be. These constraints exclude large fraction of the parameter region where the Higgs widths show significant deviation from the standard model predictions. Nevertheless, even if superparticles and the heavy Higgses are out of the reach of 14TeV LHC, the deviation may be large enough to be observed at future $e^+e^-$ collider experiments.Endo, MotoiMon, 16 Feb 2015 18:28:51 GMThttp://ilcdoc.linearcollider.org/record/606222015Off-shell Higgs signal and total width determination at the LHC
http://ilcdoc.linearcollider.org/record/60572
A substantial off-shell Higgs boson signal in the gluon fusion and vector boson fusion H --> ZZ and H --> WW channels at the Large Hadron Collider (LHC) facilitates a novel, complementary approach to constraining the total Higgs width Gamma_H. With LHC Run 1 data, experimental analyses by CMS and ATLAS find Gamma_H < 5.4 Gamma_H,SM and Gamma_H < [4.5,7.5] Gamma_H,SM at 95% confidence level, respectively, where Gamma_H,SM is the expected value in the Standard Model at the measured Higgs boson mass. I review the theoretical basis of the new approach and discuss its significance in comparison to other methods to bound and measure the Higgs width at the LHC and future colliders.Kauer, NikolasTue, 10 Feb 2015 18:18:02 GMThttp://ilcdoc.linearcollider.org/record/605722015Studies of the superconducting traveling wave cavity for high gradient LINAC
http://ilcdoc.linearcollider.org/record/60571
Use of a traveling wave (TW) accelerating structure with a small phase advance per cell instead of standing wave may provide a significant increase of accelerating gradient in a superconducting linear accelerator. The TW section achieves an accelerating gradient 1.2-1.4 larger than TESLA-shaped standing wave cavities for the same surface electric and magnetic fields. Recent tests of an L-band single-cell cavity with a waveguide feedback demonstrated an accelerating gradient comparable to the gradient in a single-cell ILC-type cavity from the same manufacturer. This article presents the next stage of the 3- cell TW resonance ring development which will be tested in the traveling wave regime. The main simulation results of the microphonics and Lorentz Force Detuning (LFD) are also considered.Avrakhov, PavelTue, 10 Feb 2015 18:18:01 GMThttp://ilcdoc.linearcollider.org/record/605712015Future tests of Higgs compositeness: direct vs indirect
http://ilcdoc.linearcollider.org/record/60545
We estimate the reach of the 14 TeV LHC and future hadronic and leptonic colliders in the parameter space of the minimal composite Higgs model, outlining the complementarity of direct resonance searches and indirect information from the measurements of the Higgs boson couplings. The reach on electroweak charged spin-one resonances, taken here as representative direct signatures, is obtained from the current 8 TeV LHC limits by an extrapolation procedure which we outline and validate. The impact of electroweak precision tests, and their possible improvement at future colliders, is also quantified.Thamm, AndreaFri, 06 Feb 2015 18:10:45 GMThttp://ilcdoc.linearcollider.org/record/605452015The Electron/Muon Specific Two Higgs Doublet Model at e+ e- Colliders
http://ilcdoc.linearcollider.org/record/60505
Recently, Kajiyama, Okada and Yagyu (KOY) proposed an electron/muon specific two Higgs doublet model. In this model, an S3 symmetry suppresses flavor changing neutral currents instead of a Z2 symmetry. In the "Type I" version of the model, the heavy Higgs bosons have a greatly enhanced coupling to electrons and muons. KOY studied the phenomenology of the heavy Higgs bosons at the LHC. In this paper, the phenomenology at electron-positron colliders is studied. For the heavy Higgs mass range between 150 and 210 GeV, bounds from LEP-200 are stronger than those from the LHC. The model allows for the interesting possibility that muon pair production at the ILC can be mediated by s-channel Higgs exchange. This requires an energy scan. The scanning rate and necessary resolution are discussed.Johansen, Aria RTue, 03 Feb 2015 18:05:22 GMThttp://ilcdoc.linearcollider.org/record/605052015Higgs mass 125 GeV and g-2 of the muon in Gaugino Mediation Model
http://ilcdoc.linearcollider.org/record/60500
Gaugino mediation is very attractive since it is free from the serious flavor problem in the supersymmetric standard model. We show that the observed Higgs boson mass at around 125 GeV and the anomaly of the muon g-2 can be easily explained in gaugino mediation models. It should be noted that no dangerous CP violating phases are generated in our framework. Furthermore, there are large parameter regions which can be tested not only at the planned International Linear Collider but also at the coming 13-14 TeV Large Hadron Collider.Harigaya, KeisukeFri, 30 Jan 2015 17:58:13 GMThttp://ilcdoc.linearcollider.org/record/605002015Probing top-Z dipole moments at the LHC and ILC
http://ilcdoc.linearcollider.org/record/60465
We investigate the weak electric and magnetic dipole moments of top quark-Z boson interactions at the Large Hadron Collider (LHC) and the International Linear Collider (ILC). Their vanishingly small magnitude in the Standard Model makes these couplings ideal for probing New Physics interactions and for exploring the role of top quarks in electroweak symmetry breaking. In our analysis, we consider the production of two top quarks in association with a Z boson at the LHC, and top quark pairs mediated by neutral gauge bosons at the ILC. These processes yield direct sensitivity to top quark-Z boson interactions and complement indirect constraints from electroweak precision data. Our computation is accurate to next-to-leading order in QCD, we include the full decay chain of top quarks and the Z boson, and account for theoretical uncertainties in our constraints. We find that LHC experiments will soon be able to probe weak dipole moments for the first time.RÃ¶ntsch, RaoulMon, 26 Jan 2015 17:51:01 GMThttp://ilcdoc.linearcollider.org/record/604652015Discrete Glimpses of the Physics Landscape after the Higgs Discovery
http://ilcdoc.linearcollider.org/record/60463
What is the Higgs boson telling us? What else is there? How do we find it? This talk discusses these current topics in particle physics in the wake of the Higgs discovery, with particular emphasis on the discrete symmetries CP and R-parity, not forgetting flavour physics and dark matter, and finishing with some remarks about possible future colliders.Ellis, JohnFri, 23 Jan 2015 17:45:41 GMThttp://ilcdoc.linearcollider.org/record/604632015The leptophilic dark matter with $Z'$ interaction: from indirect searches to future $e^+ e^-$ collider searches
http://ilcdoc.linearcollider.org/record/60456
We investigate the scenario where the dark matter only interacts with the charged leptons in the standard model via a neutral vector mediator $Z'$. Such a scenario with a 430 GeV dark matter can fit the recent positron fluxes observed by the AMS-02 Collaborations, with the reasonable boost factors. We study the possibility of searching such leptophilic $Z'$ via its lepton final states and invisible decay modes at the future electron-positron colliders, such as the International Linear Collider (ILC) and the Compact Linear Collider (CLIC). We find that for the benchmark models with $Z'$ mass from 1.0 TeV to 1.5 TeV, the searches for the invisible decays of $Z'\to \bar \chi \chi$ is easily achieved at the CLIC 1.5 TeV runs via the mono-photon process. However, lighter $Z'$ with mass from 0.5 TeV to 0.8 TeV are challenging to see. The di-lepton plus single photon channel can reveal the $Z'$ mass at the ILC and CLIC with moderate luminosities.Chen, NingTue, 20 Jan 2015 17:40:11 GMThttp://ilcdoc.linearcollider.org/record/604562015Study of $B \to K_0^*(1430)K^{(*)}$ decays in QCD Factorization Approach
http://ilcdoc.linearcollider.org/record/60431
Within the QCD factorization approach, we calculate the branching fractions and $CP$ asymmetry parameters of 12 $B \to K_0^*(1430)K^{(*)}$ decay modes under the assumption that the scalar meson $K_0^*(1430)$ is the first excited state or the lowest lying ground state in the quark model. We find that the decay modes with the scalar meson emitted, have large branching fractions due to the enhancement of large chiral factor $r_\chi^{K_0^*}$. The branching fractions of decays with the vector meson emitted, become much smaller owing to the smaller factor $r_\chi^{K^*}$. Moreover, the annihilation type diagram will induce large uncertainties because of the extra free parameter dealing with the endpoint singularity. For the pure annihilation type decays, our predictions are smaller than that from PQCD approach by 2-3 orders of magnitudes. These results will be tested by the ongoing LHCb experiment, forthcoming Belle-II experiment and the proposing circular electron-positron collider.Li, YingMon, 19 Jan 2015 17:38:28 GMThttp://ilcdoc.linearcollider.org/record/604312015Study of Higgs-gauge boson anomalous couplings through $e^-e^+ \rightarrow W^-W^+H$ at ILC
http://ilcdoc.linearcollider.org/record/60394
In this work, Higgs couplings with gauge bosons is probed through $e^-e^+ \rightarrow W^-W^+H$ in an effective Lagrangian framework. An ILC of 500 $GeV$ center of mass energy with possible beam polarization is considered for this purpose. The reach of ILC with integrated luminosity of 300 $fb^{-1}$ in the determination of both the CP-conserving and CP-violating parameters are obtained. Sensitivity of the probe of each of these couplings on the presence of other couplings is investigated. The most influential couplings parameters are $\bar c_W=-\bar c_B$. Other parameters of significant effect are $\bar c_{HW}$ and $\bar c_{HB}$ among the CP-conserving ones, and $\tilde c_{HW}$ and $\tilde c_{HB}$ among the CP-violating ones. CP-violating parameter, $\tilde c_\gamma$ seems to have very little influence on the process considered. Detailed study of the angular distributions have presented a way to disentangle the effect of some of these couplings.Kumar, SatendraThu, 15 Jan 2015 17:31:32 GMThttp://ilcdoc.linearcollider.org/record/603942015Probing WWgamma coupling through e gamma --> nu W at ILC
http://ilcdoc.linearcollider.org/record/60367
The anomalous WWgamma coupling is probed through e gamma--> nu W at the ILC. With a spectacular single lepton final state, this process is well suited to study the above coupling. Within the narrow-width approximation, a semi-analytical study of the secondary lepton energy-angle double distribution is performed. Cross section measurements can probe delta-kappa-gamma to about +/- 0.004 for a luminosity of 100 /fb at 500 GeV center of mass energy with unpolarised electron beam. The limits derivable on lambda-gamma are comparatively more relaxed. These limits can be improved significantly by considering the angle and energy distributions of the final state muon. More importantly, the angular distributions at fixed energy values, and energy distribution at fixed angles present very interesting possibility of distinguishing the case of lambda-gamma=0, lambda-gamma < 0, lambda-gamma > 0.Kumar, SatendraWed, 14 Jan 2015 17:40:17 GMThttp://ilcdoc.linearcollider.org/record/603672015Single Higgs boson production at the ILC in the left-right twin Higgs model
http://ilcdoc.linearcollider.org/record/60366
In this work, we analyze three dominant single SM-like Higgs boson production processes in the left-right twin Higgs model (LRTHM): the Higgs-strahlung (HS) process $e^{+}e^{-}\rightarrow Zh$, the vector boson fusion (VBF) process $e^{+}e^{-}\to \nu\bar{\nu}h$ and the associate production with top pair process $e^{+}e^{-}\to t\bar{t}h$ for three possible energy stages of the International Linear Collider (ILC), and compared our results with the expected experimental accuracies for various accessible Higgs decay channels. The following observations have been obtained: (i) In the reasonable parameter space, the LRTHM can generate moderate contributions to theses processes with polarized beams; (ii) Among various Higgs boson decay channels, the $b\bar{b}$ signal strength is most sensitive to the LRTHM due to the high expected precision. For the $t\bar{t}h$ production process, the absolute value of $\mu_{b\bar{b}}$ may deviate from the SM prediction by over $8.7\%$ and thus may be detectable at the future ILC with $\sqrt{s}=1$ TeV; (iii) The future ILC experiments may give strong limit on the scale parameter $f$: for the case of ILC-250 GeV, for example, the lower limit for parameter $f$ of the LRTHM is $f > 1150$ GeV at the $2\sigma$ level.Liu, Yao-BeiWed, 14 Jan 2015 17:40:16 GMThttp://ilcdoc.linearcollider.org/record/603662015