arXiv subjects

T. Tada

Publications and source records attributed to T. Tada.

9 recordsLinked to original sources

arXiv2026

Transient fluid removal at soft interfaces: Stationary squeeze-out and dynamic scraping in a block-on-flat contact

Fluid removal from rubber-substrate interfaces is crucial for maintaining friction during walking and vehicle braking on contaminated surfaces. We study the transient friction of rectangular rubber blocks sliding against tile and glass surfaces lubricated with water, glycerol, mud, or silicone grease. Two block configurations with different lengths in the sliding direction were tested after different stationary waiting times. For water, stationary squeeze-out is nearly complete before sliding begins. For glycerol, both stationary squeeze-out and sliding-induced fluid removal are important. For mud and grease, the steady-sliding state is reached after a sliding distance of the order of the block length, with little dependence on the preceding waiting time, showing that sliding-induced scraping dominates fluid removal for highly viscous substances. Dividing the contact into shorter blocks accelerates fluid removal by reducing the drainage distance and increasing the number of leading edges. Stationary squeeze-out calculations based on the measured surface roughness are in reasonably good agreement with the glycerol experiments. The results provide design guidelines for rubber tread blocks with multiscale drainage channels and sufficient compliance to promote transient fluid removal.

cond-mat.soft↗

arXiv2025

Development of the Beam Monitor Detectors for the Low-E Beamline at the CERN SPS H2 Line

A series of beam tests were conducted at the KEK AR test beamline in ordet to investigate the performance of a prototype detector for instrumentation in the low-E beamline at the CERN H2 line. For the silicon strip detector, the simultaneous readout of all strips of the X-Y detector was evaluated, in addition to the detection efficiency being assessed through coincidences with the trigger scintillators. The results demonstrated the successful acquisition of data with full strip readout and the reconstruction of the two-dimensional beam profile. Furthermore, we are contemplating the incorporation of GAGG crystals, an inorganic scintillator characterized by a high light yield ($\sim$$5 \times 10^{4}$ photons/MeV) and a brief time constant ($\sim$60 ns), within the newly developed time-of-flight detector. We assessed the resolution of time-of-flight based on the data, with the objective of achieving the required performance benchmarks through future improvements to the time-of-tlight detector.

physics.ins-det↗

arXiv2024

Measurements of the charge ratio and polarization of cosmic-ray muons with the Super-Kamiokande detector

We present the results of the charge ratio ($R$) and polarization ($P^{\mu}_{0}$) measurements using the decay electron events collected from 2008 September to 2022 June by the Super-Kamiokande detector. Because of its underground location and long operation, we performed high precision measurements by accumulating cosmic-ray muons. We measured the muon charge ratio to be $R=1.32 \pm 0.02$ $(\mathrm{stat.}{+}\mathrm{syst.})$ at $E_{\mu}\cos \theta_{\mathrm{Zenith}}=0.7^{+0.3}_{-0.2}$ $\mathrm{TeV}$, where $E_{\mu}$ is the muon energy and $\theta_{\mathrm{Zenith}}$ is the zenith angle of incoming cosmic-ray muons. This result is consistent with the Honda flux model while this suggests a tension with the $\pi K$ model of $1.9\sigma$. We also measured the muon polarization at the production location to be $P^{\mu}_{0}=0.52 \pm 0.02$ $(\mathrm{stat.}{+}\mathrm{syst.})$ at the muon momentum of $0.9^{+0.6}_{-0.1}$ $\mathrm{TeV}/c$ at the surface of the mountain; this also suggests a tension with the Honda flux model of $1.5\sigma$. This is the most precise measurement ever to experimentally determine the cosmic-ray muon polarization near $1~\mathrm{TeV}/c$. These measurement results are useful to improve the atmospheric neutrino simulations.

hep-ex↗

arXiv2024

Some comments on the fracture of viscoelastic solids

Crack propagation in viscoelastic solids like rubber is of great practical importance. Shrimali and Lopez-Pamies have proposed a new interesting approach for the crack propagation in viscoelastic solids. We give comments on the validity of the theory and point out some effects not included in the theory.

cond-mat.soft↗

arXiv2018

Real-time evolution method and its application to 3$\alpha$ cluster system

A new theoretical method is proposed to describe the ground and excited cluster states of atomic nuclei. The method utilizes the equation-of-motion of the Gaussian wave packets to generate the basis wave functions having various cluster configurations. The generated basis wave functions are superposed to diagonalize the Hamiltonian. In other words, this method uses the real time as the generator coordinate. The application to the $3\alpha$ system as a benchmark shows that the new method works efficiently and yields the result consistent with or better than the other cluster models. Brief discussion on the structure of the excited $0^+$ and $1^-$ states is also made.

nucl-th↗

arXiv2004

Loops versus Matrices - The nonperturbative aspects of noncritical string

The nonperturbative aspects of string theory are explored for non-critical string in two distinct formulations: loop equations and matrix models. The effects corresponding to D-brane in these formulations are especially investigated in detail. It is shown that matrix models can universally yield a definite value of the chemical potential for an instanton while loop equations can not. This implies that string theory may not be nonperturbatively formulated solely in terms of closed strings.

hep-th↗

arXiv1999

Noncommutative Yang-Mills in IIB Matrix Model

We show that twisted reduced models can be interpreted as noncommutative Yang-Mills theory. Based upon this correspondence, we obtain noncommutative Yang-Mills theory with D-brane backgrounds in IIB matrix model. We propose that IIB matrix model with D-brane backgrounds serve as a concrete definition of noncommutative Yang-Mills. We investigate D-instanton solutions as local excitations on D3-branes. When instantons overlap, their interaction can be well described in gauge theory and AdS/CFT correspondence. We show that IIB matrix model gives us the consistent potential with IIB supergravity when they are well separated.

hep-th↗

arXiv1999

IIB Matrix Model

We review our proposal for a constructive definition of superstring, type IIB matrix model. The IIB matrix model is a manifestly covariant model for space-time and matter which possesses N=2 supersymmetry in ten dimensions. We refine our arguments to reproduce string perturbation theory based on the loop equations. We emphasize that the space-time is dynamically determined from the eigenvalue distributions of the matrices. We also explain how matter, gauge fields and gravitation appear as fluctuations around dynamically determined space-time.

hep-th↗

arXiv1998

Space-Time Structures from IIB Matrix Model

We derive a long distance effective action for space-time coordinates from a IIB matrix model. It provides us an effective tool to study the structures of space-time. We prove the finiteness of the theory for finite $N$ to all orders of the perturbation theory. Space-time is shown to be inseparable and its dimensionality is dynamically determined. The IIB matrix model contains a mechanism to ensure the vanishing cosmological constant which does not rely on the manifest supersymmetry. We discuss possible mechanisms to obtain realistic dimensionality and gauge groups from the IIB matrix model.

hep-th↗