arXiv subjects

Taikan Suehara

Publications and source records attributed to Taikan Suehara.

At least 37 records · Page 2Linked to original sources

arXiv2020

Analysis of SiW-ECAL technological prototype beam test with electron beam

The beam test for the SiW-ECAL technological prototype was conducted using electron beam in June-July 2019 at DESY test beam facility in Hamburg, Germany. In the beam test, there were two main programs: MIP program (without tungsten) and shower program (with tungsten). The purposes of the MIP program are energy calibration, pedestal uniformity/stability assessment, TDC operation test, and retrigger verification. On the other hand, the shower program aims to evaluate energy resolution through beam energy measurement. In addition, several operation tests with FEV13 were also conducted such as individual threshold control and auto gain mode. This article presents the performance of the technological prototype of SiW-ECAL, mainly focusing on the version of FEV13-Jp.

physics.ins-det↗

arXiv2019

Tests of the Standard Model at the International Linear Collider

We present an overview of the capabilities that the International Linear Collider (ILC) offers for precision measurements that probe the Standard Model. First, we discuss the improvements that the ILC will make in precision electroweak observables, both from W boson production and radiative return to the Z at 250 GeV in the center of mass and from a dedicated GigaZ stage of running at the Z pole. We then present new results on precision measurements of fermion pair production, including the production of b and t quarks. We update the ILC projections for the determination of Higgs boson couplings through a Standard Model Effective Field Theory fit taking into account the new information on precision electroweak constraints. Finally, we review the capabilities of the ILC to measure the Higgs boson self-coupling.

hep-ex↗

arXiv2019

Study of fermion pair events at the 250 GeV ILC

Precise measurements of electroweak processes at the International Linear Collider (ILC) will provide unique opportunities to explore new physics beyond the Standard Model. Fermion pair production events are sensitive to new interactions involving a new heavy gauge boson or an electroweak interacting massive particle (EWIMP).We studied the mass reach of new particles at the ILC with $\sqrt{s}=250$ GeV by using $e^+ e^-\to e^+ e^-$and $e^+ e^-\to μ^+ μ^-$ events. We show that a mass reach for BSM particles can be determined with 90% confidence level using a toy Monte Carlo technique.

hep-ex↗

arXiv2018

Study of fermion pair productions at the ILC with center-of-mass energy of 250 GeV

Precise measurements of electroweak processes at the International Linear Collider (ILC) will provide unique opportunities to explore new physics beyond the Standard Model. Fermion pair productions are sensitive to a new contact interaction or a new heavy gauge boson by comparing cross section and angular distribution with expectations of the new physics models. In this proceedings we report a simulation study of fermion pair productions at a center-of-mass energy of 250 GeV, with a focus on lepton pairs, to demonstrate the potential of the first phase of the ILC.

hep-ex↗

arXiv2017

Performance evaluation of PSD for silicon ECAL

We are developing position sensitive silicon detectors (PSD) which have an electrode at each of four corners so that the incident position of a charged particle can be obtained using signals from the electrodes. It is expected that the position resolution the electromagnetic calorimeter (ECAL) of the ILD detector will be improved by introducing PSD into the detection layers. In this study, we irradiated collimated laser beams to the surface of the PSD, varying the incident position. We found that the incident position can be well reconstructed from the signals if high resistance is implemented in the p+ layer. We also tried to observe the signal of particles by placing a radiative source on the PSD sensor.

physics.ins-det↗

arXiv2016

Optimization of layer composition for ILD ECAL

International Large Detector (ILD) adopts Particle Flow Algorithm (PFA) for precise measurement of multiple jets. The electromagnetic calorimeter (ECAL) of ILD has two candidates sensor technologies for PFA, which are pixelized silicon sensors and scintillator-strips with silicon photomultipliers. Pixelized silicon sensors have higher granularity for PFA, however they have an issue of cost reduction. In contrast, scintillator-strips have an advantage of relatively low cost and a disadvantage of degradation of position resolution by ghost hits, which are generated by orthogonal arrangement. Hybrid ECAL using both candidates is proposed to supplement these disadvantages. In this paper, we report an optimization study of the hybrid ECAL using detector simulation.

physics.ins-det↗

arXiv2015

A study of the measurement precision of the Higgs boson decaying into tau pairs at the ILC

We evaluate the measurement precision of the production cross section times the branching ratio of the Higgs boson decaying into tau lepton pairs at the International Linear Collider (ILC). We analyze various final states associated with the main production mechanisms of the Higgs boson, the Higgs-strahlung and WW-fusion processes. The statistical precision of the production cross section times the branching ratio is estimated to be 2.6% and 6.9% for the Higgs-strahlung andWW-fusion processes, respectively, with the nominal integrated luminosities assumed in the ILC Technical Design Report; the precision improves to 1.0% and 3.4% with the running scenario including possible luminosity upgrades. The study provides a reference performance of the ILC for future phenomenological analyses.

hep-ex↗

arXiv2015

LCFIPlus: A Framework for Jet Analysis in Linear Collider Studies

We report on the progress in flavor identification tools developed for a future $e^+e^-$ linear collider such as the International Linear Collider (ILC) and Compact Linear Collider (CLIC). Building on the work carried out by the LCFIVertex collaboration, we employ new strategies in vertex finding and jet finding, and introduce new discriminating variables for jet flavor identification. We present the performance of the new algorithms in the conditions simulated using a detector concept designed for the ILC. The algorithms have been successfully used in ILC physics simulation studies, such as those presented in the ILC Technical Design Report.

physics.ins-det↗

arXiv2015

Characteristic study of silicon sensor for ILD ECAL

Excellent jet energy measurement is important at the International Linear Collider (ILC) because most of interesting physics processes decay into multi-jet final states. We employ a particle flow method to reconstruct particles, hence International Large Detector (ILD) needs high spatial resolution which can separate each particle in jets. We study pixelized silicon sensors as active material of ILD Silicon electro- magnetic calorimeter (SiECAL). This paper reports studies of temperature and humidity dependence on dark current and response of laser injection.

hep-ex↗

arXiv2015

Measuring BR($h \to τ^+ τ^-$) at the ILC: a full simulation study

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 multivariate analysis technique.

hep-ex↗

arXiv2014

Study of top quark pair production near threshold at the ILC

We report on a study of top pair production at the International Linear Collider (ILC) around center of mass energy (E$_{\rm CM}$) = 350 GeV using an ILD detector simulator based on the Detailed Baseline Design (DBD) configuration. Here we will report on a result of 6-Jet final state, $t\ bar{t} \rightarrow bWbW \rightarrow bqqbqq$. A result for the 4-Jet final state, $t\ bar{t} \rightarrow bWbW \rightarrow bqqblν$, which has almost the same statics as that of the 6-Jet final state will be included in the future. For an energy scan of 11 center of mass energy points (340 - 350GeV) and two beam polarization combinations (P($e^+,\ e^-$) = ($\pm$0.3, $\mp$0.8)) with 10 fb$^{-1}$ each, the statistical errors on the top quark Yukawa coupling, its mass and width are estimated. The results are $δy_t$ = 4.2%, $δm_t$ = 16 MeV in potential subtracted scheme (PS), and $δΓ_t$ = 21 MeV.

hep-ex↗

arXiv2014

A study of silicon sensor for ILD ECAL

The International Large Detector (ILD) is a proposed detector for the International Linear Collider (ILC). It has been designed to achieve an excellent jet energy resolution by using Particle Flow Algorithms (PFA), which rely on the ability to separate nearby particles within jets. PFA requires calorimeters with high granularity. The ILD Electromagnetic Calorimeter (ECAL) is a sampling calorimeter with thirty tungsten absorber layers. The total thickness of this ECAL is about 24 X$_0$, and it has between 10 and 100 million channels to make high granularity. Silicon sensors are a candidate technology for the sensitive layers of this ECAL. Present prototypes of these sensors have 256 5.5$\times$5.5 mm$^2$ pixels in an area of 9$\times$9 cm$^2$.We have measured various properties of these prototype sensors: the leakage current, capacitance, and full depletion voltage. We have also examined the response to an infrared laser to understand the sensor's response at its edge and between pixel readout pads, as well the effect of different guard ring designs. In this paper, we show results from these measurements and discuss future works.

physics.ins-det↗

arXiv2014

Full Simulation Study of the Higgs Branching Ratio into Tau Lepton Pairs at the ILC with $\sqrt{s} = 500$ GeV

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 $e^+ e^- \to ν\overlineν h$ are expected to be the most sensitive channels at $\sqrt{s} = 500$ GeV. Using a multivariate analysis technique, we estimate the expected relative measurement accuracy of the branching ratio $Δ(σ\cdot \mathrm{BR}) / (σ\cdot \mathrm{BR})$ to be 4.7% and 7.4% for the $q \overline{q} h$ and $ν\overlineν h$ final states, respectively. The results are cross-checked using a cut-based analysis.

hep-ex↗

arXiv2014

Study of Tracking and Flavor Tagging with FPCCD Vertex Detector

One of the major physics goals at the ILC is the precise measurement of the Higgs coupling constants to b-quarks and c-quarks. To achieve this measurement, we need a high-performance vertex detector leading to precise flavor tagging. For this purpose, we are developing the Fine Pixel CCD (FPCCD) vertex detector. In this paper, we will report on the development status of FPCCDTrackFinder, a new track finder improving tracking efficiency, especially in the low $p_t$ region, and an evaluation result of the flavor tagging performance with FPCCDTrackFinder in the FPCCD vertex detector.

physics.ins-det↗

arXiv2013

Physics at the CLIC e+e- Linear Collider -- Input to the Snowmass process 2013

This paper summarizes the physics potential of the CLIC high-energy e+e- linear collider. It provides input to the Snowmass 2013 process for the energy-frontier working groups on The Higgs Boson (HE1), Precision Study of Electroweak Interactions (HE2), Fully Understanding the Top Quark (HE3), as well as The Path Beyond the Standard Model -- New Particles, Forces, and Dimensions (HE4). It is accompanied by a paper describing the CLIC accelerator study, submitted to the Frontier Capabilities group of the Snowmass process.

hep-ex↗

arXiv2013

Evaluation of measurement accuracy of $h \to τ^+ τ^-$ branching ratio at the ILC with $\sqrt{s} = 250$ GeV and 500 GeV

We evaluate the measurement accuracy of the branching ratio of $h \to τ^+ τ^-$ at $\sqrt{s} = 250$ GeV and 500 GeV at the ILC with the ILD detector simulation. For the $\sqrt{s} = 250$ GeV, we assume the Higgs mass of $M_h = 120$ GeV, branching ratio of $\mathrm{Br}(h \to τ^+ τ^-) = 8.0 \ %$, beam polarization of $P(e^-, e^+) = (-0.8, +0.3)$, and integrated luminosity of $\int L \ dt = 250 \ \mathrm{fb ^{-1}}$. The Higgs-strahlung process $e^+ e^- \to Zh$ with $Z \to e^+ e^-$, $Z \to μ^+ μ^-$, $Z \to q\bar{q}$ mode are analyzed. The measurement accuracy is calculated to be $Δ(σ\cdot \mathrm{Br}) / (σ\cdot \mathrm{Br}) = 3.5 \ %$. The scaled result to $M_h = 125$ GeV is estimated to be $4.2 \ %$. For the $\sqrt{s} = 500$ GeV, we assume the Higgs mass of $M_h = 125$ GeV, branching ratio of $\mathrm{Br}(h \to τ^+ τ^-) = 6.32 \ %$, beam polarization of $P(e^-, e^+) = (-0.8, +0.3)$, and integrated luminosity of $\int L \ dt = 500 \ \mathrm{fb ^{-1}}$. The Higgs-strahlung process $e^+ e^- \to Zh$ with $Z \to q\bar{q}$ mode and $WW$-fusion process $e^+ e^- \to ν_e \bar{ν_e} h$ are analyzed. The measurement accuracy is calculated to be $Δ(σ\cdot \mathrm{Br}) / (σ\cdot \mathrm{Br}) = 5.7 \ %$ for Higgs-strahlung with $Z \to q\bar{q}$ and $7.5 \ %$ for $WW$-fusion.

hep-ex↗

arXiv2011

Improved jet clustering algorithm with vertex information for multi-bottom final states

In collider physics at the TeV scale, there are many important processes which involve six or more jets. The sensitivity of the physics analysis depends critically on the performance of the jet clustering algorithm. We present a full detector simulation study for the ILC of our new algorithm which makes use of secondary vertices which improves the reconstruction of b jets. This algorithm will have many useful applications, such as in measurements involving a light Higgs which decays predominantly into two b quarks. We focus on the measurement of the Higgs self-coupling, which has so far proven to be challenging but is one of the most important measurements at the ILC.

hep-ex↗

arXiv2011

Discrimination of New Physics Models with the International Linear Collider

The large hadron collider (LHC) is anticipated to provide signals of new physics at the TeV scale, which are likely to involve production of a WIMP dark matter candidate. The international linear collider (ILC) is to sort out these signals and lead us to some viable model of the new physics at the TeV scale. In this article, we discuss how the ILC can discriminate new physics models, taking the following three examples: the inert Higgs model, the supersymmetric model, and the littlest Higgs model with T-parity. These models predict dark matter particles with different spins, 0, 1/2, and 1, respectively, and hence comprise representative scenarios. Specifically, we focus on the pair production process, e+e- -> chi+chi- -> chi0chi0W+W-, where chi0 and chi+- are the WIMP dark matter and a new charged particle predicted in each of these models. We then evaluate how accurately the properties of these new particles can be determined at the ILC and demonstrate that the ILC is capable of identifying the spin of the new charged particle and discriminating these models.

hep-ph↗