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.
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 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…
Higgs decay branching ratios at future Higgs factories can be measured by directly exploiting class numeration. Given the clean environment at a lepton collider, it is possible to build an event sample highly enriched in Higgs bosons and essentially unbiased for any decay mode. The sample can be partitioned into categories using event properties linked to the expected Higgs decay modes. The counts per category are used to fit the Higgs branching ratios in a model independent way. The result of the fit is the set of branching ratios, independent from a Higgs production mode measurement. We pres…
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.
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.
Higgs Self-Coupling Measurement at a Linear Collider at 550 GeV
Deutsches Elektronen-Synchrotron DESY（德国电子同步加速器）；Department of Physics, Universität Hamburg（汉堡大学物理系）；SLAC National Accelerator Laboratory（斯坦福直线加速器中心）；International Center for Elementary Particle Physics (ICEPP), The University of Tokyo（东京大学基本粒子物理国际中心）
This paper describes a novel algorithm for tagging jets originating from the hadronisation of strange quarks (strange-tagging) with the future International Large Detector (ILD) at the International Linear Collider (ILC). It also presents the first application of such a strange-tagger to a Higgs to strange ($h \rightarrow s\bar{s}$) analysis with the $P(e^-,e^+) = (-80\%,+30\%)$ polarisation scenario, corresponding to 900 fb$^{-1}$ of the initial proposed 2000 fb$^{-1}$ of data which will be collected by ILD during its first 10 years of data taking at $\sqrt{s} = 250$ GeV. Upper limits on the …
Although the LHC experiments have searched for and excluded many proposed new particles up to masses close to 1 TeV, there are many scenarios that are difficult to address at a hadron collider. This talk will review a number of these scenarios and present the expectations for searches at an electron-positron collider such as the International Linear Collider. The cases discussed include the light Higgsino, the stau lepton in the coannihilation region relevant to dark matter, and heavy vector bosons coupling to the s-channel in e$^+$e$^-$ annihilation. The studies are based on the ILD concept a…
We study the prospects for discovering an extra scalar boson $S^0$ at the International Linear Collider (ILC) based on a full simulation of the International Large Detector (ILD). In order to provide results in an as model-independent way as possible, the analysis uses the recoil of the scalar against a $Z$ boson decaying into a pair of muons, $e^+e^- \to μμS^{0}$. This process serves as a physics benchmark for the ILD detector performance at $\sqrt{s}=500$ GeV, specifically for the muon ID and momentum resolution, as well as for the identification of initial state radiation photons and their …
Precise measurement of the Higgs boson properties is an important issue of the International Linear Collider (ILC) experiment. We studied the accuracy of the Higgs mass reconstruction in the ZH->qqH multi-jet process with the Higgs mass of MH = 120 GeV at sqrt(s) = 250 GeV with the ILD detector model. In this study, we obtained the reconstructed Higgs mass of M_H = 120.79 +- 0.089 GeV and 5.3% measurement accuracy of the cross-section for ZH->qqbb with the integrated luminosity of L=250 fb^{-1} data samples.
In this communication, the mass declined for the decay channel, e+e- -> ZH -> e+e- + X, as measured by the ILD detector was studied. The Higgs mass is assumed to be 120 GeV and the center of mass energy is 250 GeV. For an integrated luminosity of 250 fb-1, the accuracy of the reconstruction and the good knowledge of the initial state allow for the measurement of the Higgs boson mass with a precision of about 100 MeV.
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…
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 $m^p_{\rm recoil}$…
Tau-lepton decays with up to two $π^0$'s in the final state, $τ^+ \to π^+ \barν_τ$, $ρ^+ (π^+π^0) \barν_τ$, $a^+_1 (π^+π^0π^0) \barν_τ$, are used to study the performance of the barrel part of the silicon-tungsten electromagnetic calorimeter (Si-W ECAL) of the International Large Detector (ILD) at the future $e^+-e^-$ International Linear Collider. A correct reconstruction of the tau decay mode is crucial for constraining the tau spin state and measuring the Higgs boson CP state in $H\to τ^+τ^-$ decays. About 95% of $π^+ \barν_τ$ and 90% of $ρ^+\barν_τ$ and $a^+_1\barν_τ$ decays from $e^+e^-\t…
Precise measurement of the Higgs boson properties is an important issue of the International Linear Collider (ILC) experiment to verify the particles mass generation mechanism that the coupling strength between the Higgs boson and the fermions or vector bosons are proportional to the mass of each particle. Thus the measurement of the branching ratio of the Higgs boson an important issue to understand the mass of each particle. In this analysis, measurement accuracy of the Higgs boson branching ratio in the ZH->qqH hadronic decay mode was studied with the cut-based analysis in Higgs mass of M_{…
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 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 …
In this paper we present results of determination of the statistical precision of Higgs branching fraction measurement, for Higgs decay to ZZ$^\ast$ pairs at 3 TeV and 350 GeV CLIC. Measurements are simulated with the CLIC_ILD detector model, taking into consideration all relevant physics and beam-induced background processes. It is shown that the product of the branching fraction BR(${H\rightarrow\thinspace ZZ^\ast}$) and the Higgs production cross-section can be measured with a relative statistical uncertainty of 3% (18%) at 3 TeV (350 GeV) center-of-mass energy, using semileptonic final sta…
We evaluate the expected measurement accuracy of the branching ratio of the Standard Model Higgs boson decaying into tau pairs at the ILC with a full simulation of the ILD detector concept. We assume a Higgs mass of 125 GeV, a branching ratio of BR($h \to τ^+ τ^-$) = 6.32%, a beam polarization of electron (positron) of -0.8(+0.3), and an integrated luminosity of 250 fb$^{-1}$. The Higgs-strahlung process $e^+ e^- \to Zh$ with $Z \to q\overline{q}$ is analyzed. We estimate the measurement accuracy of the branching ratio $Δ(σ\times \mathrm{BR}) / (σ\times \mathrm{BR})$ to be 3.4% with using a mu…
In many analyses in Higgs, top and electroweak physics, the kinematic reconstruction of the final state is improved by constrained fits. This is a particularly powerful tool at $e^{+}e^{-}$ colliders, where the initial state four-momentum is known and can be employed to constrain the final state. A crucial ingredient to kinematic fitting is an accurate estimate of the measurement uncertainties, in particular for composed objects like jets. This contribution will show how the particle flow concept, which is a design-driver for most detectors proposed for future Higgs factories, can -- in additi…
The potential for the measurement of the branching ratio of the Standard Model-like Higgs boson decay into a mu+mu- pair at 1.4 TeV CLIC is analysed. The study is performed using the fully simulated CLIC_ILD detector concept, taking into consideration all the relevant physics and the beam-induced backgrounds. Despite the very low branching ratio of the H->mu+mu- decay, we show that the product of the branching ratio times the Higgs production cross section can be measured with a statistical uncertainty of 38 percent, assuming an integrated luminosity of 1.5 ab^-1 collected in five years of the…
Precise measurement of Higgs boson couplings is an important task for International Linear Collider (ILC) experiments and will facilitate the understanding of the particle mass generation mechanism. In this study, the measurement accuracies of the Higgs boson branching fractions to the $b$ and $c$ quarks and gluons, $ΔBr(H\to b\bar{b},\sim c\bar{c},\sim gg)/Br$, were evaluated with the full International Large Detector model (\texttt{ILD\_00}) for the Higgs mass of 120 GeV at the center-of-mass (CM) energies of 250 and 350 GeV using neutrino, hadronic and leptonic channels and assuming an inte…
Results are presented for the search for invisible Higgs boson production using the full LHC dataset corresponding to integrated luminosity of 5.1 fb^-1 and 19.6 fb^-1 of proton-proton collision data at sqrt(s)= 7 TeV and 8 TeV (respectively) collected by the CMS detector. The invisible Higgs is searched for in final states of missing transverse energy, with two leptons from a recoiling Z boson. No significant excess is found beyond standard model predictions, and limits are obtained on the branching fraction of the Higgs boson to invisible particles.
In many analyses in Higgs, top and electroweak physics, the kinematic reconstruction of the final state is improved by constrained fits. This is a particularly powerful tool at $e^{+}e^{-}$ colliders, where the initial state four-momentum is known and can be employed to constrain the final state. A crucial ingredient to kinematic fitting is an accurate estimate of the measurement uncertainties, in particular for composed objects like jets. This contribution will show how the particle flow concept, which is a design-driver for most detectors proposed for future Higgs factories, can -- in additi…
The branching fraction measurement of the SM-like Higgs boson decay into two muons at 1.4 TeV CLIC will be described in this paper contributed to the LCWS13. The study is performed in the fully simulated ILD detector concept for CLIC, taking into consideration all the relevant physics and the beam-induced backgrounds, as well as the instrumentation of the very forward region to tag the high-energy electrons. Higgs couplings are known to be sensitive to BSM physics and we prove that BR times the Higgs production cross section can be measured with approximately 35.5% statistical accuracy in four…
Toward a Measurement of the Higgs Boson Mass with Natural-Width Precision at FCC-ee
Massachusetts Institute of Technology（麻省理工学院）；Brookhaven National Laboratory（布鲁克海文国家实验室）；Laboratoire AstroParticule et Cosmologie, CNRS/IN2P3（天体粒子与宇宙学实验室，法国国家科学研究中心/法国国家原子核及粒子物理研究所）；CERN（欧洲核子研究组织）
This presentation gives the prospects of measuring the general Lorentz structures of $VVH$ ($V=Z$, $γ$ and $W$) couplings at the International Linear Collider (ILC). Sensitivities to Higgs CP-even and CP-odd structures are evaluated by using various Higgs production channels and employing measurements of kinematical distributions. The evaluation is performed based on full detector simulation of the International Large Detector (ILD) at center-of-mass energies $\sqrt{s}=$ 250 and 500 GeV. Combined sensitivities on the anomalous $ZZH$ couplings are provided for a realistic operating scenario of …
This contribution to LCWS2016 presents recent developments within the CLICdp collaboration. An updated scenario for the staged operation of CLIC has been published; the accelerator will operate at 380 GeV, 1.5 TeV and 3 TeV. The lowest energy stage is optimised for precision Higgs and top physics, while the higher energy stages offer extended Higgs and BSM physics sensitivity. The detector models CLIC_SiD and CLIC_ILD have been replaced by a single optimised detector; CLICdet. Performance studies and R&D in technologies to meet the requirements for this detector design are ongoing.
We report on studies of the $e^+e^- \to HZ$ process with the subsequent decay of the Higgs boson $H \to Z Z^\star$, where the $Z Z^\star$ combination is reconstructed in the final states with two jets and two leptons. The analysis is performed using Monte Carlo data samples obtained with detailed ILD detector simulation assuming the integrated luminosity 2 ab$^{-1}$, the beam polarizations ${\cal{P}}_{e^-e^+} = (-0.8, +0.3)$, and the center-of-mass energy $\sqrt{s}$ = 250 GeV. The analysis is also repeated for the case of two 0.9 ab$^{-1}$ data samples with polarizations ${\cal{P}}_{e^-e^+} = …
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 …
The design of detector concepts has been driven for a long time by requirements on transverse momentum, impact parameter and jet energy resolutions, as well as hermeticity. Only rather recently it has been realised that the ability to idenfity different types of charged hadrons, in particular kaons and protons, could have important applications at Higgs factories like the International Linear Collider (ILC), ranging from improvements in tracking, vertexing and flavour tagging to measurements requiring strangeness-tagging. While detector concepts with gaseous tracking, like a time projection ch…
The design of detector concepts has been driven for a long time by requirements on transverse momentum, impact parameter and jet energy resolutions, as well as hermeticity. Only rather recently it has been realised that the ability to idenfity different types of charged hadrons, in particular kaons and protons, could have important applications at Higgs factories like the International Linear Collider (ILC), ranging from improvements in tracking, vertexing and flavour tagging to measurements requiring strangeness-tagging. While detector concepts with gaseous tracking, like a time projection ch…
The future Compact Linear Collider (CLIC) offers a possibility for a rich precision physics programme, in particular in the Higgs sector through the energy staging. This is the first paper addressing the measurement of the Standard Model Higgs boson decay into two muons at 1.4 TeV CLIC. With respect to similar studies at future linear colliders, this paper includes several novel contributions to the statistical uncertainty of the measurement. The later includes the Equivalent Photon Approximation and realistic forward electron tagging based on energy deposition maps in the forward calorimeters…
A search for the Higgs boson produced in association with a W or Z boson and decaying to bottom quarks is presented. A sample of approximately 24/fb of data recorded by the CMS experiment at the Large Hadron Collider, operating at center-of-mass energies of 7 TeV and 8 TeV in 2011 and 2012, respectively, is used to search for events consistent with the signature of two b jets recoiling with high momentum from a W(lnu), Z(ll), or Z(nunu) decay, where l = electron or muon (or hadronically-decaying tau particle in the case of W bosons). Observed signal significance and 95% confidence level upper …
A future e+e- collider, such as the ILC or CLIC, would allow the Higgs sector to be probed with a precision significantly beyond that achievable at the High-Luminosity LHC. A central part of the Higgs programme at an e+e- collider is the model-independent determination of the absolute Higgs couplings to fermions and to gauge bosons. Here the measurement of the e+e-->HZ Higgsstrahlung cross section, using the recoil mass technique, sets the absolute scale for all Higgs coupling measurements. Previous studies have considered e+e- ->ZH with Z->l+l-, where l = electron or muon. In this paper it is…
The precision of the yield measurement of the Higgs boson decaying into a pair of $Z$ bosons process at the Circular Electron Positron Collider (CEPC) is evaluated. Including the recoil $Z$ boson associated with the Higgs production (Higgsstrahlung) total three $Z$ bosons are involved for this channel, from which final states characterized by the presence of a pair of leptons, quarks, and neutrinos are chosen for the signal. Two analysis approaches are compared and the final precision of $σ_{\mathrm{ZH}}{\cdot}$BR($H \rightarrow ZZ^{*}$) is estimated to be 7.9% using a multivariate analysis te…
The precision measurements of the Higgs properties is crucial for a better understanding of electroweak symmetry breaking. It can be first achieved at the ILC\pcite{Behnke2013} at $\sqrt{s}=250\rm ~GeV$ via the Higgs-strahlung production process $e^+e^-\rightarrow ZH$. The hadronic decay mode $Z\rightarrow \bar{q}q$ constitutes more than $65%$ of the total, a factor 10 more than $Z\rightarrow μμ$. An analysis based solely on the $Z$ jet pair information could thus lead to a high statistics and provide a minimum biased Higgs sample. A study of the feasibility of such analysis is shown here, bas…
Experimental prospects for precision observables in $e^{-}e^{+}\rightarrow q\bar{q}$ with $q=b,c$ processes at the ILC operating at 250 and 500 GeV of center of mass
The Higgs boson decay modes to $b$ and $c$ quarks are crucial for many Higgs precision measurements. The presence of semileptonic decays in the jets originating from $b$ and $c$ quarks causes missing energy due to the undetectable neutrinos. A correction for the missing neutrino momenta can be derived from the kinematics of the decay up to a two-fold ambiguity. The correct solution can be identified by a kinematic fit, which exploits the well-known initial state at an $e^{+}e^{-}$ collider by adjusting the measured quantities within their uncertainties to fulfill the kinematic constraints. The…
We evaluate the expected measurement accuracy of the branching ratio of the Standard Model Higgs boson decaying into tau lepton pairs $h \to τ^+ τ^-$ at the ILC with a center-of-mass energy of $\sqrt{s} = 500$ GeV with a full simulation of the ILD detector. We assume a Higgs mass of $M_h = 125$ GeV, a branching ratio of $\mathrm{BR}(h \to τ^+ τ^-) = 6.32 \%$, beam polarizations of $P(e^+, e^-) = (-0.8,+0.3)$, and an integrated luminosity of $\int L dt = 500 \mathrm{fb^{-1}}$. The Higgs-strahlung process $e^+ e^- \to Zh$ with $Z \to q \overline{q}$ and the $WW$-fusion process $e^+ e^- \to ν\ove…
The model independent measurement of the absolute ZH cross section of the Higgsstrahlung process e+e- -> ZH is an unique measurement at the ILC indispensable for measuring the Higgs couplings and their deviations from the Standard Model in order to identify new physics models. The performance in measuring the ZH cross section using events in which the Higgs boson recoils against a Z boson which decays into a pair of muons or electrons has been demonstrated based on full simulation of the ILD detector for three center of mass energies 250, 350, and 500 GeV, and two beam polarizations (Pe-,Pe+) …
A search for dark matter produced in association with a Higgs boson decaying to a pair of bottom quarks is performed in proton-proton collisions at a center-of-mass energy of 13 TeV collected with the CMS detector at the LHC. The analyzed data sample corresponds to an integrated luminosity of 35.9 fb$^{-1}$. The signal is characterized by a large missing transverse momentum recoiling against a bottom quark-antiquark system that has a large Lorentz boost. The number of events observed in the data is consistent with the standard model background prediction. Results are interpreted in terms of li…
Both the ATLAS and CMS collaborations have reported a Standard Model Higgs-like excess at around $m_h = 125$ GeV. If an SM-like Higgs particle is discovered in this particular mass range, an important additional test of the SM electroweak symmetry breaking sector is the measurement of the Higgs self-interactions. We investigate the prospects of measuring the Higgs self-coupling for $m_h=125 \gev$ in the dominant SM decay channels in boosted and unboosted kinematical regimes. We further enhance sensitivity by considering dihiggs systems recoiling against a hard jet. This configuration exhibits …
We explore the possibility of discovering the mirror baryons and electrons of the Mirror Twin Higgs model in direct detection experiments, in a scenario in which these particles constitute a subcomponent of the observed DM. We consider a framework in which the mirror fermions are sub-nano-charged, as a consequence of kinetic mixing between the photon and its mirror counterpart. We consider both nuclear recoil and electron recoil experiments. The event rates depend on the fraction of mirror DM that is ionized, and also on its distribution in the galaxy. Since mirror DM is dissipative, at the lo…
Jet flavor tagging with Particle Transformer for Higgs factories
International Center for Elementary Particle Physics, The University of Tokyo（东京大学基础粒子物理国际中心）；Department of Physics, Graduate School of Science, The University of Tokyo（东京大学理学研究科物理学系）；MI-6 Ltd.（MI-6有限公司）
