The process ee-->ZH allows to measure the Higgs boson in the recoil mass spectrum against the Z boson without any assumptions on the Higgs boson decay. We performed a full simulation and reconstruction of ee-->ZH using the MOKKA and MARLIN packages describing the LDC detector. The Z is reconstructed from its decays into electrons and muons. The mass of the Higgs boson is set to 120 GeV. Assuming a centre-of-mass energy of 250 GeV and an integrated luminosity of 50/fb the Higgs boson mass and the Higgs-strahlung cross section can be measured with a precision of 120 MeV and 9%, respectively.
This proceeding summarizes the Higgs recoil mass and Higgs-strahlung cross-section study done for the Letter of Intent (LOI) of the International Large Detector (ILD) Concept. Assuming a Higgs mass of 120 GeV, working at 250 GeV center of mass energy with beam parameters RDR250 and beam polarization, this full simulation study predicts that, the ILD detector can achieve 37 MeV precision on the Higgs mass measurement and 3.3% on the cross-section measurement from the muon channel, while 83 MeV and 4.9% from the electron channel, if we have 250 inverse fb integrated luminosity.
This proceeding reports a study of the impacts of the SB2009 beam parameters on the Higgs recoil mass and Higgs-Strahlung cross-section measurements based on a dedicated fast simulation algorithm of the ILD detector. The study shows worse results from SB2009 beam parameters than the previous RDR beam parameters, because of the smaller luminosity. However, Travel Focus (TF) technology can recover the degradation to certain level.
Precision measurements of SM Higgs recoil mass and cross-section are performed with the Higgs-Strahlung process ee -> Zh, with Z -> mumu and Z -> ee at 230 GeV and 250 GeV center of mass energies, presuming Mh=120GeV, assuming the integrated luminosity is 500 1/fb, based on full simulations of several detector models for the ILC. Results are given and compared in this article, of the two center of mass energies, and of several detector models. According to the studies, the Higgs mass can be determined with a statistical error of 39 MeV and 3.6% statistical error for the cross-section.
It is difficult to measure the $WW$-fusion Higgs production process ($e^+e^- \to ν\barν h$) at a lepton collider with a center of mass energy of 240-250 GeV due to its small rate and the large background from the Higgsstrahlung process with an invisible $Z$ ($e^+e^- \to hZ,\,Z\to ν\barν$). We construct a modified recoil mass variable, $m^p_{\rm recoil}$, defined using only the 3-momentum of the reconstructed Higgs particle, and show that it can better separate the $WW$-fusion and Higgsstrahlung events than the original recoil mass variable $m_{\rm recoil}$. Consequently, the $m^p_{\rm recoil}$…
We summarize the status of SM Higgs boson searches at the Fermilab Tevatron performed by the CDF and DØcollaborations, with an emphasis on measurements at large Higgs mass, and derive sensitivity prospects for the upcoming increase in integrated luminosity.
In the following, the prospects for measuring the SM Higgs properties at the LHC are reviewed, in particular its mass, width, spin, CP eigenstates as well as its couplings to the SM fermions and gauge bosons. The possibility of performing the difficult trilinear Higgs self-coupling measurement is also discussed.
An overview on the prospects for Higgs Boson searches with the CMS detector is presented. Projections have been made to estimate the potential to a possible discovery or exclusion of the Higgs Boson during the run at a center of mass energy of 7 TeV at the LHC, with a recorded integrated luminosity of approximately 1 fb-1, conditions expected by the end of 2011
As soon as a significant signal in one of the Higgs boson discovery channels is observed, it will be important to establish its nature. To do this, a precise measurements of its properties is important. In this article the prospects to measure the Higgs boson mass, width, spin and CP-quantum numbers, couplings to the known Standard Model particles and self-couplings by the ATLAS experiment are summarized.
The search for the Higgs boson is a major physics goal of the future Large Hadron Collider. The discovery potential is described as a function of the Higgs mass. It is shown that a Standard Model Higgs boson can be discovered within the first year of data taking. The status of MSSM Higgs searches is also discussed.
We report on results obtained at the Tevatron by the CDF and D0 collaborations up to June 2008 (2.4 fb-1), on searches for standard model (SM) Higgs bosons having a high mass (135-200 GeV). High mass Higgs bosons decay dominantly in WW and the presented searches are performed in the leptonic decay modes of the W's. Both direct production (ppbar -> H) and associated production (ppbar -> WH) are studied and eventually combined with all channels available at the Tevatron. Prospects for SM Higgs searches with the full projected Tevatron statistics are also given.
The status of the search at LEP2 for the Higgs in the Standard Model (SM) and in the minimal supersymmetric extension of the Standard Model MSSM) is reviewed. A preliminary lower limit of 95.5/c^2 at 95% C.L. on the SM Higgs is obtained after a preliminary analysis of the data collected at sqrt(s)= 189 GeV. For standard choices of MSSM parameter sets, the search for the neutral Higgs bosons h and A leads to preliminary 95% C.L. exclusion lower limits of 83.5GeV/c^2 and 84.5 GeV/c^2, respectively.
This note describes the details of a simulation study of the Higgs boson production for processes in which the Higgs is produced together with a well measurable di-lepton system using the proposal of the ILD detector for its Letter of Intent. The analysis is optimised for the measurement of the Higgs-strahlung process, i.e. e+e- -> HZ. The cross section can be determined with a precision of 2-3% and by combining the decay channels a precision of ~30 MeV is obtained for the mass of the Higgs boson. The background can be largely reduced and the analysis exhibits a sensitivity to the configuratio…
The investigation of the electroweak symmetry breaking is one of the primary tasks of the experiments at the CERN Large Hadron Collider (LHC). The potential of the ATLAS experiment for the discovery of the Higgs boson(s) in Standard Model and Minimal Supersymmetric Standard Model is presented, with emphasis on studies which have been completed recently.
A linear e+e- collider provides excellent possibilities for precision measurements of the properties of the Higgs boson. At energies close to the Z-Higgs threshold, the Higgs boson can be studied in recoil against a Z boson, to obtain not only a precision mass measurement but also direct measurements of the branching ratios for most decay modes, including possible decay to invisible species. At higher energies, the Higgs boson coupling to top quarks and the Higgs boson self-coupling can also be measured. At energies approaching 1 TeV and above, the rising cross section for Higgs production in …
We report on the accuracy of the measurement of the Higgs boson mass and the total cross section of the process e+e- -> ZH that would be achieved in a linear collider operating at a centre-of-mass energy of 350 GeV, assuming an integrated luminosity of 500 (1/fb). For that we have exploited the recoil mass off the Z using its leptonic decays into electron and muon pairs. The Higgs mass is determined with 150 MeV accuracy, the recoil mass resolution is about 1.5 GeV and the cross section is obtained with a statistical error of 3%.
The investigation of the properties of the Higgs boson, especially a test of the predicted linear dependence of the branching ratios on the mass of the final state is going to be an integral part of the physics program at colliders at the energy frontier for the foreseeable future. The large Higgs boson production cross section at a 3TeV CLIC machine allows for a precision measurement of the Higgs branching ratios. The cross section times branching ratio of the decays H->bb, H->cc and H->μμ of a Standard Model Higgs boson with a mass of 120 GeV can be measured with a statistical uncertainty of…
The Higgs boson physics reach of the CMS detector with 300(0) fb-1 of proton-proton collisions at sqrt{s} = 14 TeV is presented. Precision measurements of the Higgs boson properties, Higgs boson pair production and self-coupling, rare Higgs boson decays, and the potential for additional Higgs bosons are discussed.
We report on the potential for the discovery of a Standard Model Higgs boson with the vector boson fusion mechanism in the mass range $115<M_H<500 \gev/$c$^2$ with the ATLAS experiment at the LHC. Feasibility studies at hadron level followed by a fast detector simulation have been performed for $H\to W^{(*)}W^{(*)}\to l^+l^-\sla{p_T}$, $H\toγγ$ and $H\to ZZ\to l^+l^-q\bar{q}$. The preliminary results obtained here show a large discovery potential in the range $115<M_H<300 \gev/$c$^2$. Results obtained with multivariate techniques are reported for a number of channels.
This article summarizes a talk given at Higgs Hunting 2014 on projections of the sensitivity of the ATLAS and CMS experiments to beyond Standard Model Higgs physics at the High Luminosity Large Hadron Collider. We describe results on vector boson scattering, searches for additional neutral Higgs bosons in two Higgs doublet models and flavour changing neutral current top decays.
An overview of recent results in Higgs boson physics obtained with the ATLAS and CMS experiments at the Large Hadron Collider located at CERN, Geneva, is presented. The focus is on measurements of the properties of the recently discovered Higgs boson with a mass of about 125 GeV. A brief selection of results in searches for Higgs bosons beyond the Standard Model is given, and prospects of future Higgs boson measurements and searches at the LHC are discussed.
Searches for this Higgs boson are reaching an exciting time. This proceeding reports the progress on Standard Model Higgs boson searches at the Tevatron and the prospects for Higgs boson searches at the Large Hadron Collider. Also reported are the results of non Standard Model searches and prospects at the Tevatron, Large Hadron Collide and B factories. Included in this result are the first limits on the mass of the Standard Model Higgs boson at high masses beyond the kinematic reach of the Large Electron Positron collider.
We study the prospects of measuring the decay of the Higgs boson into a pair of muons at the International Linear Collider (ILC). The study is performed at center-of-mass energies of 250\,GeV and 500\,GeV, with fully-simulated Monte-Carlo samples based on the International Large Detector (ILD). The expected precision on cross section times branching ratio $σ\times \mathrm{BR}(h \to μ^+ μ^-)$ has been evaluated to be 24.9{\%} for an integrated luminosity of 2\,ab$^{-1}$ at 250\,GeV. This result improves to 17.5{\%} in combination with 4\,ab$^{-1}$ of 500\,GeV data. We also quantify the impact o…
An accurate determination of the Higgsstrahlung cross section is one of the main objectives at a future electron-positron collider. It allows for the only Higgs boson decay model independent measurement of the total Higgs width. Current results use the recoil mass shape method. That technique can be applied to Higgsstrahlung events with Z boson decays into muons, into electrons and, with reservations, into quarks. The samples built from Higgsstrahlung events with Z boson decays into taus and neutrinos are not used in previous analyses. We present here a new method, the reference sample method.…
The LHC Run-1 was very successful and included the discovery of a new particle with mass of about 125 GeV compatible with the Higgs boson predicted by the Standard Model. The prospects for Higgs physics at the high-luminosity LHC and at future colliders are presented. In particular, the ultimate precision attainable for the couplings measurements of the 125 GeV particle with elementary fermions and bosons is discussed along with prospects for self-coupling measurements, for the ATLAS and CMS detectors at the upgraded LHC.
The prospects for measuring the branching fraction of $H \to μ^+ μ^-$ at the International Linear Collider (ILC) have been evaluated based on a full detector simulation of the International Large Detector (ILD) concept, considering centre-of-mass energies ($\sqrt{s}$) of 250 GeV and 500 GeV. For both $\sqrt{s}$ cases, the two final states $e^+ e^- \to q\overline{q}H$ and $e^+ e^- \to ν\overlineνH$ have been analyzed. For integrated luminosities of 2 ab$^{-1}$ at $\sqrt{s} = 250$ GeV and 4 ab$^{-1}$ at $\sqrt{s} = 500$ GeV, the combined precision on the branching fraction of $H \to μ^+ μ^-$ is …
The possibility to observe a Higgs boson having a mass between 300 and 600 GeV and to measure its couplings to vector bosons and top quark with CMS at the LHC is studied. Six different signatures are analyzed. The possibility to separate the Higgs events produced through weak boson fusion from the Higgs produced through gluon fusion using the forward going jets emitted in the weak boson fusion process is discussed for each of these different channels. The results are then used to determine the possible statistical errors on the ratio between the two Higgs decay branching fractions when it deca…
The discovery of the Higgs boson at the LHC opened up a new possibility to obtain a precise understanding of the origin of mass and the structure of the vacuum. Several theories beyond the Standard Model predict an extended Higgs sector, with additional scalar particles. We outline the complementary search possibilities for these beyond Standard Model Higgs bosons at the LHC and at possible future high-energy collider facilities.
This document is prepared for the LCWS2016 conference proceedings. It reviews the current results on the Higgs CP property measurements from both ATLAS and CMS experiments in the Higgs to diboson decays, and in the Vector Boson Fusion production of Higgs via the ditau decay channel. The projected sensitivity of the ditau signal in HL-LHC is briefly discussed. Finally, it gives the prospects for the CP measurement in the Higgs to ditau decay with the tau substructure developments at both collaborations.
We show prospects on a search for invisible decays of a Higgs boson at the Large Hadron Collider (LHC) and High Luminosity LHC (HL-LHC). This search is performed on a Higgs boson produced in association with a Z boson. We expect that the branching ratio of 17-22% (6-14%) could be excluded at 95% confidence level with 300 fb^{-1} (3000 fb^{-1}) of data at sqrt(s)=14 TeV. The range indicates different assumptions on the control of systematic uncertainties. Interpretations with Higgs-portal dark matter models are also considered.
We analyze the Tevatron reach for neutral Higgs bosons in the Minimal Supersymmetric Standard Model (MSSM), using current exclusion limits on the Standard Model Higgs. We study four common benchmark scenarios for the soft supersymmetry-breaking parameters of the MSSM, including cases where the Higgs decays differ significantly from the Standard Model, and provide projections for the improvements in luminosity and efficiency required for the Tevatron to probe sizeable regions of the $(m_A, \tanβ)$ plane.
The document is prepared for the LCWS2016 conference proceedings. The expected status of Higgs physics at the end of Run-3 is presented. The current Run-2 status is briefly reviewed, and the expected Higgs reach after the HL-LHC period is also summarized for some channels.
In the minimal supersymmetric standard models, neutralino dark matter with mass of $m_χ\sim m_Z/2\sim 45$ GeV and $m_χ\sim m_h/2\sim 62$ GeV can have the thermal relic abundance $Ω_{χ_1}h^2\simeq 0.120$ via the $Z$- and Higgs-resonant annihilations, respectively, while avoiding all the current constraints. Phenomenology of such scenarios is determined only by three parameters, Bino mass $M_1$, Higgsino mass $μ$, and $\tanβ$, in the limit that all other supersymmetric particles and heavy Higgs bosons are decoupled. In this paper, we comprehensively study the constraints and future prospects of …
Searches for Beyond the Standard Model Higgs processes in the context of Minimal Supersymmetric Standard Model and Next to MSSM are presented. The results are based on the first LHC run of pp collision data recorded by the ATLAS and CMS experiments at the CERN Large Hadron Collider at centre-of-mass energies of 7 and 8 TeV, corresponding to integrated luminosities of about 5 and 20 fb$^{-1}$ respectively. Current searches constrain large parts of the parameter space. No evidence for BSM Higgs is found.
A feasibility to use the hadronic decay mode of $Z$ for the model independant measurement of the total cross section of Higgs-strahlung process $(σ_{Zh})$ at a future $e^+e^-$ collider was studied. For the recoil mass measurement from hadronic decay of $Z$, a simple cut based analysis was applied on samples produced by the ILD full detector simulation at $\sqrt{s}=350$ GeV and 500 GeV using the ILC beam parameters. At $350$ GeV, a bump in the recoil mass distribution was reconstructed, and $Δσ_{Zh}/σ_{Zh}$ = 3.4% was obtained assuming 165 fb$^{-1}$ data with $e^-(e^+)$ beam polarization of -80…
We evaluate the prospects for measuring $BR(h\toγγ)$ for a Standard-Model-like Higgs boson at the Next Linear $e^+e^-$ Collider in the $e^+e^-\to Z^*\to Z h$ and $e^+e^-\toν_e\antiν_e h$ production modes. Relative merits of different machine energy/luminosity strategies and different electromagnetic calorimeter designs are evaluated. We emphasize the importance of measuring $BR(h\toγγ)$ in order to obtain the total width of a light Higgs boson and thereby the $b\anti b$ partial width that will be critical in discriminating between the SM Higgs and the Higgs bosons of an extended model.
An updated luminosity staging baseline for CLIC is presented. Assuming accelerator ramp-up and up-time scenarios that are harmonized with those of other potential future colliders, CLIC will deliver 1 ab^-1 at sqrt(s)=380 GeV, 2.5 ab^-1 at sqrt(s)=1.5 TeV, and 5 ab^-1 at sqrt(s)=3 TeV. The complete programme will take 25-30 years. The baseline scenario for luminosity sharing between the two electron beam polarisation states is also discussed. Updated Higgs coupling sensitivities are given for this new luminosity staging baseline.
The prospects of observing the non-resonant di-Higgs production in the Standard Model at the proposed high energy upgrade of the LHC, $viz.$ the HE-LHC$~$($\sqrt{s}=27~{\rm TeV}$ and $\mathcal{L} = 15~{\rm ab^{-1}}$) is studied. Various di-Higgs final states are considered based on their cleanliness and signal yields. The search for the non-resonant double Higgs production at the HE-LHC is performed in the $b\bar{b}γγ$, $b\bar{b}τ^{+}τ^{-}$, $b\bar{b}WW^{*}$, $WW^{*}γγ$, $b\bar{b}ZZ^{*}$ and $b\bar{b}μ^{+}μ^{-}$ channels. The signal-background discrimination is performed through multivariate a…
We summarise the prospects for Higgs boson physics at future proton-proton colliders with centre of mass (c.m.) energies up to 100 TeV. We first provide the production cross sections for the Higgs boson of the Standard Model from 13 TeV to 100 TeV, in the main production mechanisms and in subleading but important ones such as double Higgs production, triple production and associated production with two gauge bosons or with a single top quark. We then discuss the production of Higgs particles in beyond the Standard Model scenarios, starting with the one in the continuum of a pair of scalar, fer…
The scenario of two mass-degenerate Higgs bosons within the general two-Higgs-doublet model (2HDM) is revisited. We focus on the global picture when two $CP$-even Higgs bosons of $h$ and $H$ are nearly mass-degenerate. A global fit to the signal strength of the 125 GeV Higgs measured at the LHC is performed. Based on the best-fit result of the 2HDM mixing angles $(α,β)$, theoretical constraints, charged and $CP$-odd Higgs boson direct search constraints and the electroweak precision constraints are imposed to the 2HDM parameter space. We present the signal predictions of the $(4b\,, 2b\,2γ)$ c…
An interesting model of dark matter involves a hidden sector decoupled from Standard Model (SM) fields except for some portal interaction. A concrete realization of this is the Hidden Abelian Higgs Model, which gives rise to decays of the SM Higgs boson into a pair of new bosons, called $Z_{\mathrm{d}}$ or dark photons. This note explores prospects for the search for such dark photons at the ILC with $\sqrt{s}=250$ GeV, where the dark photons decay promptly. For the $H\rightarrow Z_{\mathrm{d}}Z_{\mathrm{d}}\rightarrow 4\ell$ ($\ell = e,μ$) final state, it follows closely recent similar search…
We study future prospects of the stau which contributes to the Higgs coupling to di-photon. The coupling is sensitive to new physics and planned to be measured at percent levels in future colliders. We show that, if the excess of the coupling is measured to be larger than 4 %, the lightest stau is predicted to be lighter than about 200 GeV by taking vacuum meta-stability conditions into account. Such a stau can be discovered at ILC. Moreover, we show how accurately the stau contribution to the coupling can be reconstructed from the information that is available at ILC. We also argue that, if t…
We analyze the prospects of observing relatively light charged Higgs bosons ($h^{\pm}$) in their decays via $h^{-} \to s \bar c + s \bar u$ at the upcoming Future Circular Collider in hadron-electron mode (FCC-eh) with $\sqrt s \approx 3.5$ TeV. Assuming that the intermediate Higgs boson ($h_2$) is Standard Model (SM)-like, we study the production of $e^- b \to ν_e h^{-} b$ (also $b$ could be $\bar b$ in both initial and final states) in the framework of the Next-to-Minimal Supersymmetric Standard Model (NMSSM). We consider constraints from Dark Matter (DM), super-particle and the Higgs boson …
We present an overview of a study on precise mass reconstruction and identification of charged hadrons ($π^{\pm}$, $K^{\pm}$, $p$) using time-of-flight measurements in the electromagnetic calorimeter of a typical Higgs factory detector. Time-of-flight measurements can take advantage of fast timing Si sensors with a time resolution in the order of 10 ps. A precise time-of-flight measurement might contribute to the kaon mass determination and can improve particle identification in the momentum regions inaccessible for the $dE/dx$ method. In this contribution, we discuss the current status and th…
We analyze the Tevatron and Large Hadron Collider (LHC) reach for the Higgs sector of the Minimal Supersymmetric Standard Model (MSSM) in the presence of explicit CP-violation. Using the most recent studies from the Tevatron and LHC collaborations, we examine the CPX benchmark scenario for a range of CP-violating phases in the soft trilinear and gluino mass terms and compute the exclusion/discovery potentials for each collider on the $(M_{H^+}, \tanβ)$ plane. Projected results from Standard Model (SM)-like, non-standard, and charged Higgs searches are combined to maximize the statistical signi…
The Littlest Higgs model with T-parity is providing an attractive solution to the fine-tuning problem. This solution is only entirely natural if its intrinsic symmetry breaking scale f is relatively close to the electroweak scale. We examine the constraints using the latest results from the 8 TeV run at the LHC. Both direct searches and Higgs precision physics are taken into account. The constraints from Higgs couplings are by now competing with electroweak precision tests and both combined exclude f up to 694 GeV or 560 GeV depending on the implementation of the down-type Yukawa sector. Direc…
The future Large Hadron Electron Collider (LHeC) would enable collisions of an intense electron beam with either protons or heavy ions at the High Luminosity-Large Hadron Collider (HL- LHC). With a center of mass energy greater than a TeV and a high luminosity, the LHeC would be a new-generation collider for deep-inelastic scattering (DIS) and a significant facility for precise Higgs physics, complementing pp and electron-positron colliders. Anomalous hadronic decay signatures of the Higgs Boson, such as those into three or more partons, are challenging to detect at the LHC due to high backgro…
The search for CP violation in interactions of the Higgs boson with either fermions or bosons provides attractive reference measurements in the Particle Physics Community Planning Exercise (a.k.a. "Snowmass"). Benchmark measurements of CP violation provide a limited and well-defined set of parameters that could be tested at the proton, electron-positron, photon, and muon colliders, and compared to those achieved through study of virtual effects in electric dipole moment measurements. We review the current status of these CP-sensitive studies and provide projections to future measurements.
Within models containing a very light scalar particle coupled to the 125 GeV Higgs boson, we present the first detailed study of Higgs decays into three of these light scalars. We determine model-independent conditions which the scalar sector after electroweak symmetry breaking has to satisfy in order for the three-body channel to become relevant. Using a specific model -- the real scalar singlet-extension of the Standard Model (SM) -- we then identify scenarios, where the rates of scalar three-body Higgs decays are comparable to or even exceed those of the well-studied two-body channel. All t…
Thermal dark matter scenarios based on light (sub-GeV) fermions typically require the presence of an extra dark sector containing both a massive dark photon along with a dark Higgs boson. The latter generates both the dark photon mass and an additional mass term for the dark sector fermions. This simple setup has both rich phenomenology and bright detection prospects at high-intensity accelerator experiments. We point out that in addition to the well studied pseudo-Dirac regime, this model can achieve the correct relic density in three different scenarios, and examine in details their properti…
One of the most attractive features of a linear collider is the ability to extend its energy reach in stages, and to adapt the running plan flexibly in terms of maximum centre-of-mass energy and time spent at each stage. The baseline luminosity staging scenario for CLIC is well-established, and has been used to obtain sensitivity projections for Standard Model measurements and Beyond Standard Model scenarios. Here, as an exercise to illustrate what could be obtained from an alternative running scenario, Higgs coupling sensitivities are presented for the case where more data is collected at the…
