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Takubo, Y., Hodgkinson, R. N., Ikematsu, K., Fujii, K., Okada, N., & Yamamoto, H. (2013). Measuring anomalous couplings in H -> WW* decays at the International Linear Collider. Phys. Rev. D, 88(1), 013010–9pp.
Abstract: The measurement of the Higgs coupling to W bosons is an important test of our understanding of the electroweak symmetry-breaking mechanism. We study the sensitivity of the International Linear Collider (ILC) to the presence of anomalous HW+W- couplings using ZH -> nu(nu) over bar WW* -> nu(nu) over bar 4j events. Using an effective Lagrangian approach, we calculate the differential decay rates of the Higgs boson including the effects of new dimension-five operators. We present a Monte Carlo simulation of events at the ILC, using a full detector simulation based on GEANT4 and a real event reconstruction chain. Expected constraints on the anomalous couplings are given.
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Yamamoto, H. (2021). The International Linear Collider Project-Its Physics and Status. Symmetry-Basel, 13(4), 674–15pp.
Abstract: The discovery of Higgs particle has ushered in a new era of particle physics. Even though the list of members of the standard theory of particle physics is now complete, the shortcomings of the theory became ever more acute. It is generally considered that the best solution to the problems is an electron-positron collider that can study Higgs particle with high precision and high sensitivity; namely, a Higgs factory. Among a few candidates for Higgs factory, the International Linear Collider (ILC) is currently the most advanced in its program. In this article, we review the physics and the project status of the ILC including its energy expandability.
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Aparisi, J., Fuster, J., Irles, A., Rodrigo, G., Vos, M., Yamamoto, H., et al. (2022). m(b) at m(H): The Running Bottom Quark Mass and the Higgs Boson. Phys. Rev. Lett., 128(12), 122001–7pp.
Abstract: We present a new measurement of the bottom quark mass in the MS scheme at the renormalization scale of the Higgs boson mass from measurements of Higgs boson decay rates at the LHC: -0.31 GeV. The measurement has a negligible theory uncertainty and excellent prospects to improve at the HL-LHC and a future Higgs factory. Confronting this result and mb(mb) from low-energy measurements and mb(mZ) from Z-pole data, with the prediction of the scale evolution of the renormalization group equations, we find strong evidence for the “running” of the bottom quark mass.
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Irles, A., Marquez, J. P., Pöschl, R., Richard, F., Saibel, A., Yamamoto, H., et al. (2024). Probing gauge-Higgs unification models at the ILC with quark-antiquark forward-backward asymmetry at center-of-mass energies above the Z mass. Eur. Phys. J. C, 84(5), 537–17pp.
Abstract: The International Linear Collider (ILC) will allow the precise study of e(-)e(+)-> q (q) over bar interactions at different center-of-mass energies from the Z-pole to 1 TeV. In this paper, we discuss the experimental prospects for measuring differential observables in e(-)e(+)-> b (b) over bar and e(-)e(+) -> c (c) over bar at the ILC baseline energies, 250 and 500 GeV. The study is based on full simulation and reconstruction of the International Large Detector (ILD) concept. Two gauge-Higgs unification models predicting new high-mass resonances beyond the Standard Model are discussed. These models predict sizable deviations of the forward-backward observables at the ILC running above the Z mass and with longitudinally polarized electron and positron beams. The ability of the ILC to probe these models via high-precision measurements of the forward-backward asymmetry is discussed. Alternative scenarios at other energies and beam polarization schemes are also discussed, extrapolating the estimated uncertainties from the two baseline scenarios.
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