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NumberConferenceabstractsubmitted onStatus
9IEEE NSS/MIC 2017

ILD for the International Linear Collider (submitted by Kiyotomo Kawagoe and Karsten Buesser)

The International Large Detector (ILD) is a detector concept for the International Linear Collider (ILC), a 250-500 GeV (extendable to 1 TeV) center-of-mass high-luminosity linear electron-positron collider. The ILD is optimized with the concept of particle flow for overall event reconstruction so that it will deliver excellent performance for high-precision Higgs and top measurements, as well as high-sensitivities for possible new phenomena, utilizing the advantages of an electron-positron collider. Particle flow implies that all particles in an event, charged and neutral, are individually reconstructed. This requirement has a large impact on the design of the detector, and has played a central role in the optimisation of the system. Superb tracking capabilities and outstanding detection of secondary vertices are other important aspects. The overall layout, sub-detector technologies, expected performance, and recent progress of the ILD will be presented.

05.08.2017S
8EPS-HEP 2017

Sensitivity to anomalous VVH couplings at the ILC (submitted by Tomohisa Ogawa)

The discovery of the 125 GeV Higgs boson, which was the last missing element of the standard model (SM), provided us the insight that the electroweak symmetry breaking is done by a Higgs condensate in the vacuum, namely the Higgs mechanism. However the SM does not give the dynamics explaining why and how that Higgs condensate is formed. On the other hand, the SM can not provide candidate particles for the dark matter, and can not explain the baryon number asymmetry in our universe, etc. Therefore new physics beyond the SM is needed to answer all of those questions. Remarkably the effects of new physics will be inevitably imprinted in the properties of the Higgs boson, namely its couplings to other SM particles and its CP nature. At the future International Linear Collider (ILC), one of the most important goals is precise measurement those properties.

In this talk, we will focus on the measurement of the general Lorentz structure of couplings between Higgs and vector bosons (VVH, V=Z or W) at the ILC, based on an approach of the effective field theory. The sensitivities to both CP-even and CP-odd dimension-5 operators are evaluated by exploring various Higgs production and decay channels, in particular taking advantage of the sensitivities from differential cross sections measurements. The studies are performed based on full detector simulation of the International Large Detector (ILD), for ECM = 250 GeV and 500 GeV. Combined sensitivities are given for some realistic running scenarios of the ILC.

04.13.2017A (poster)
7EPS-HEP 2017

Prospects for electroweak precision measurements and triple gauge couplings at a staged ILC (submitted by Jenny List)

In absence of a direct discovery of new particles, precision measurements of the properties of known particles will provide the most powerful probe for phenomena beyond the Standard Model. Future electron positron linear colliders with polarised beams, like the International Linear Collider (ILC), will provide a unique laboratory for such measurements, complementary to hadron colliders. In this contribution, we will review in particular the prospects for electroweak precision measurements, like the mass of the W boson, or the weak mixing angle, as well as for measurements of charged triple gauge couplings based simulations of the ILD detector concept for the ILC. In all of these, the exact knowledge of the beam polarisation and the beam energy plays an important role. Therefore we will also discuss the precision determination of these accelerator parameters from collision data. We will pay special tribute to the most recent discussions concerning a possible first stage of the ILC operating at a center-of-mass energy of 250 or 350 GeV, but also comment of the full ILC running plan.

04.13.2017A (poster), presenter: Robert Karl
6EPS-HEP 2017

Full simulation study of the process $e^+ e^- \rightarrow b\bar{b}$ at \sqrt(s) = 250 GeV at the ILC (submitted by Roman Pöschl)

The heavy quark doublet plays a central role in the quest for new physics. The complementary between studies of electroweak top quark production and bottom quark production is therefore intuitively clear and pointed out in the literature. Let us remind that the tension between the LEP measurement and the Standard Model prediction of the forward-backward asymmetry $A_{fb}^b$ is still one of the unsolved questions in the field and may be interpreted as a first manifestation of new physics in the heavy quark sector. The process $e^+ e^- \rightarrow b\bar{b}$ at the ILC offers a unique opportunity for a final word on the tension. Polarised beams allow for a large disentangling of the coupling constants or form factors that govern the $\gamma/Z \,b\bar{b}$ vertex.

The contribution will present a detailed simulation study of the process $e^+ e^- \rightarrow b\bar{b}$ at 250\, GeV with the ILD Detector. Besides the phenomenological implications, the contribution will demonstrate that with a careful analysis of the final state the charge of the b-quarks can be determined on an event-by-event basis with the ILD Detector. Such a capability is unprecedented by past and present particle physics experiments.

04.13.2017A (poster), presenter: Sviatoslav Bilokin
5EPS-HEP 2017

Naturalness and light Higgsinos: why ILC is the right machine for SUSY discovery (submitted by Jacqueline Yan)

Radiatively-driven natural Supersymmetry, a theoretically and experimentally well-motivated framework, centers around the predicted existence of four  light, nearly mass-degenerate Higgsinos with mass $\sim 100-200$ GeV (not too far above $m_Z$). Their small mass splittings of at most 20 GeV implies very little visible energy of accompanying Standard Model particles decayed from heavier Higgsinos. Given that other SUSY particles are considerably heavy, this makes detection challenging at hadron colliders. On the other hand, the clean environment of an electron-positron collider with  $\sqrt{s}>2m_{Higgsino}$ would enable a decisive search of these required Higgsinos, and thus either the discovery or exclusion of natural SUSY.  We present a detailed simulation study of precision measurements of Higgsino masses and production cross sections at  $\sqrt{s}$ = 500 GeV of the proposed International Linear Collider currently under consideration for construction in Japan. The study is  based on a Geant4 simulation of the International Large Detector concept. We examine several benchmark points  just beyond the HL-LHC reach, with a mass spectrum containing four light Higgsinos directly accessible by the ILC, and the mass differences between the lightest SUSY particle and the heavier states ranging from about 4 to 20 GeV. It can be shown that their masses and production cross sections are able to be precisely measured to approximately 1% precision or better. These precise measurements allow for extracting the underlying weak scale SUSY parameters. The fitted parameters give predictions for the masses of heavier SUSY states, which provide motivation for future high-energy colliders. Additionally, dark matter properties may be derived. Evolution of the measured gaugino masses to high energies should allow one to distinguish the hypothesis of gaugino mass unification from other compelling possibilities such as mirage mediation.

03.31.2017A
4ALPS2017

Natural SUSY at the ILC: from MZ to the GUT scale (submitted by Mikael Berggren)

The most basic requirement for naturalness in supersymmetric models is the existence of rather light partners of the Higgs boson, the Higgsinos, at masses not too far above M_Z. Despite the pressure from LHC data on the simplest high-scale models (like the cMSSM), such light Higgsinos can still be realised in different types of GUT-scale models from NUHM2 to mirage unification models. The ILC will offer the unique discovery potential for the elusive higgsino particles and allow for precision measurements of their properties. In this contribution, prospects for the achievable precisions for masses, the very small mass splittings and polarised production cross sections will be presented. Based on these, we studied the possibilities to determine the SUSY parameters at the weak scale, and to extrapolate their running to the GUT scale. We will discuss the prospects to thereby differentiate between various GUT-scale models and SUSY breaking schemes and to predict the masses of the remaining SUSY particles. In particular the latter could provide important guidance for the energy scale of the next hadron collider after the LHC.

02.13.2017A
3ALPS2017

Scalar sector at future e+e- colliders (submitted by Ivanka Bozovic-Jelisavcic)

Future e+e- colliders offer excellent possibilities for precision studies in the Higgs sector due to the clean experimental conditions and low backgrounds compared to hadron colliders. At lower energies i.e. below 500 GeV, the Higgstrahlung is the dominant Higgs production mechanism. With the recoil mass analysis technique being the unique feature of e+e- colliders, the Higgstrahlung allows model-independent studies of the Higgs couplings as well as the access to the invisible Higgs decays. If considered simultaneously with WW-fusion dominating Higgs production at higher energies, determination of the Higgs total width is possible at a percent level. Scalar sector searches are reviewed for ILC and CEPC using recent research updates obtained with the fully simulated ILD and CEPC detectors.

02.01.2017A (, speaker: Junping Tian)
2ALPS2017

ILD for the International Linear Collider (submitted by Kiyotomo Kawagoe)

 The International Large Detector (ILD) is a detector concept for the International Linear Collider (ILC), a 250-500 GeV (extendable to 1 TeV) center-of-mass high-luminosity linear electron-positron collider. The ILD is optimized with the concept of particle flow for overall event reconstruction so that it will deliver excellent performance for high-precision Higgs and top measurements, as well as high-sensitivities for possible new phenomena, utilizing the advantages of an electron-positron collider. Particle flow implies that all particles in an event, charged and neutral, are individually reconstructed. This requirement has a large impact on the design of the detector, and has played a central role in the optimisation of the system. Superb tracking capabilities and outstanding detection of secondary vertices are other important aspects. The overall layout, sub-detector technologies, expected performance, and recent progress of the ILD will be presented.

01.17.2017R (Our abstract is merged with that of CLICdp for a more general talk.)
1Instrumentation 2017

ILD for the International Linear Collider (submitted by Kiyotomo Kawagoe)

 The International Large Detector (ILD) is a detector concept for the International Linear Collider (ILC), a 250-500 GeV (extendable to 1 TeV) center-of-mass high-luminosity linear electron-positron collider. The ILD is optimized with the concept of particle flow for overall event reconstruction so that it will deliver excellent performance for high-precision Higgs and top measurements, as well as high-sensitivities for possible new phenomena, utilizing the advantages of an electron-positron collider. Particle flow implies that all particles in an event, charged and neutral, are individually reconstructed. This requirement has a large impact on the design of the detector, and has played a central role in the optimisation of the system. Superb tracking capabilities and outstanding detection of secondary vertices are other important aspects. The overall layout, sub-detector technologies, expected performance, and recent progress of the ILD will be presented.

12.12.2016R (T. Omori gives a more general talk on behalf of LCC: "Status and Future Perspectives of the ILC Project: Accelerator / Detector R&D".)

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