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.Comment: 10 pages, 6 figures, 9 tables, revised from v

Naturalness and light Higgsinos: why ILC is the right machine for SUSY discovery

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 $m_Z$). The small mass splittings amongst the higgsinos, typically 4-20 GeV, results in very little visible energy arising from decays of the 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 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 can be precisely measured to approximately 1\% precision or better. These precise measurements allow for extracting the underlying weak scale SUSY parameters, giving predictions for the masses of heavier SUSY states. These 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 testing the hypothesis of gaugino mass unification.Comment: 6 pages, 4 figures; to appear in the proceedings for EPS-HEP2017, 5-12 July 2017, Venice, Ital

Electrophoretic deposition of cellulose nanofibers in aqueous suspensions

Cellulose is one of the most abundant organic polymers in nature and a promising biomass. Since cellulose nanofibers (CNF) have attractive features such as a low thermal expansion coefficient, a high elastic modulus, high mechanical strength, and high eco-friendliness, CNFs are envisaged to be applied for biomaterials, tissue engineering scaffolds, filtration media, and reinforcement in nanocomposites. In this study, in order to develop a coating technology with nanofibers for biomedical applications, CNFs in aqueous suspensions were deposited on titanium and aluminum substrates by an electrophoretic deposition (EPD) technique. CNFs used were obtained from Sugino Machine Ltd. (Japan). Aqueous suspensions of the CNFs were prepared using a wet pulverizing and dispersing device. The obtained 0.2wt% aqueous suspensions of the CNFs were stable and not observed the aggregation of the nanofibers. EPD was conducted in a two-electrode system, where titanium or aluminum sheets were used as anode and a platinum sheet as cathode. The constant voltages of 10-30 V were applied to the system for 10-60 seconds. After the process, it was observed that the CNFs were successfully deposited on the anodes. The deposition amount of CNFs on either anode increased linearly with an increase of the applied time at the constant voltage of 20 V. Moreover, the amount also increased as a function of the applied voltages between 10 to 30 V at the constant applied time of 30 seconds. These results indicated that negatively charged CNFs in the aqueous suspension moved to the anodes by the electrophoresis. The adhesiveness of the deposited CNFs was superior on the aluminum anode compared with the titanium anode, indicating that the interaction between them depended on the kind of metal. In conclusion, EPD of the CNFs paves the way for the development of a coating technology with nanofibers for biomedical applications

High Signal Intensity of the Cochlear Modiolus on Unenhanced T1-Weighted Images in Classical Infratentorial Superficial Siderosis

Background: Superficial siderosis (SS) results from chronic bleeding in the subarachnoid space. SS can be classified as infratentorial SS (i-SS) and supratentorial SS (s-SS). The cochlear modiolus (CM) normally shows low signal intensity (SI) on Tl-weighted images (T1WI). We noticed persistently high SI of the CM on unenhanced thin-sliced T1WI in patients with i-SS. The purpose of this study was to evaluate the correlation between SS and high SI of the CM on unenhanced T1WI. Methods: This retrospective study analyzed three cases with i-SS, eight cases with s-SS, and 23 normal controls (NC) evaluated on unenhanced thin-sliced T1WI with a three-dimensional spoiled gradient-recalled echo sequence. CM-T1SI scores of 0, 1, and 2 indicated low, iso, and high SI, respectively. In cases with scores of 2 evaluated several times, all scores were reviewed for each case. The CM-T1SI ratio was defined as the contrast ratio between the CM and the cerebellum. Differences between the three groups were statistically analyzed based on the CM-T1SI score and ratio. Receiver operative curve (ROC) analysis was used to determine the cut-off values for differentiating the i-SS group from the NC group based on the CM-T1SI ratio. Results: Two patients with i-SS had a score of 2 on all evaluations. The CM-T1SI score and ratio differed significantly between the i-SS and NC groups. The accuracy of the CM-T1SI ratio for discriminating i-SS from NC was 98.9% at a cutoff value of 0.628. Conclusion: High SI of the CM on unenhanced TIWI can be an additional characteristic finding of i-SS

Formation of ZnO thin films by photocatalytic reaction

Zinc oxide and layered zinc hydroxides were deposited from an aqueous solution of zinc nitrate at 323–358 K on a substrate plate with a very thin titanium dioxide film by a photocatalytic reaction. The amorphous or low crystalline zinc hydroxide aggregates were deposited at a low temperature. The zinc oxide crystals with about 1–2 μm-sized hexagonal columns and 10 nm-sized spheres were formed at 338–358 K. Nitrate ions in the solution were reduced to nitrite ions, and water was transformed into hydroxide ions by a photocatalytic reaction on the titanium dioxide film. The pH value increased on the substrate surface with the titanium dioxide film, which caused the zinc hydroxide formation on the film. The zinc hydroxides were then dehydrated and transformed into zinc oxide. The average crystallite size of the zinc oxide decreased with an increase in the reaction temperature because the reaction rates of the formation and dehydration of the zinc hydroxides increased which resulted in an increase in the formation rate of the crystal zinc oxide nuclei.ArticleAPPLIED CATALYSIS B-ENVIRONMENTAL. 160:651-657 (2014)journal articl

A novel technique for the measurement of the avalanche fluctuation of gaseous detectors

We have developed a novel technique for the measurement of the avalanche fluctuation of gaseous detectors using a UV laser. The technique is simple and requires a short data-taking time of about ten minutes. Furthermore, it is applicable for relatively low gas gains. Our experimental setup as well as the measurement principle, and the results obtained with a stack of Gas Electron Multipliers (GEMs) operated in several gas mixtures are presented.Comment: 7 pages, 7 figures. For the proceedings of VCI2016, to be published in Nucl. Instrum. Methods Phys. Res.

Measuring the top Yukawa coupling at the ILC at sqrt(s) = 500 GeV

We report on the feasibility of the direct measurement of the top Yukawa coupling g_t at the International Linear Collider (ILC) during its first phase of operation with a center-of-mass energy of 500 GeV. The signal and background models incorporate the non-relativistic QCD corrections which enhance the production cross section near the t-tbar threshold. The e+e- -> t tbar H signal is reconstructed in the 6-jet + lepton and the 8-jet modes. The results from the two channels are combined. The background processes considered are e+e- -> t bbar W- / tbar b W+ (which includes e+e- -> t tbar), e+e- -> t tbar Z, and e+e- -> t tbar g* -> t tbar b bar. We use a realistic fast Monte-Carlo detector simulation. Signal events are selected using event shape variables, through jet clustering, and by identifying heavy flavor jets. Assuming a Higgs mass of 120 GeV, polarized electron and positron beams with (Pe-,Pe+) = (-0.8,+0.3), and an integrated luminosity of 1 ab-1, we estimate that the e+e- -> t tbar H events can be seen with a statistical significance of 5.2 sigma, corresponding to the relative top Yukawa coupling measurement accuracy of |Delta g_t / g_t| = 10%.Comment: 9 pages, 6 figures, to be submitted to Phys. Rev.

Physics Case for the International Linear Collider

We summarize the physics case for the International Linear Collider (ILC). We review the key motivations for the ILC presented in the literature, updating the projected measurement uncertainties for the ILC experiments in accord with the expected schedule of operation of the accelerator and the results of the most recent simulation studies.Comment: 37 pages, 12 figures, 2 tables; v2 - updates of reference