Time variation of proton-electron mass ratio and fine structure constant with runaway dilaton

Recent astrophysical observations indicate that the proton-electron mass ratio and the fine structure constant have gone through nontrivial time evolution. We discuss their time variation in the context of a dilaton runaway scenario with gauge coupling unification at the string scale $M_{\rm s}$. We show that the choice of adjustable parameters allows them to fit the same order magnitude of both variations and their (opposite) signs in such a scenario.Comment: 16 pages, 1 figure, to appear in Phys. Rev.

Nanorod Size Dependence of Coherent Coupling between Individual and Collective Excitations via Transverse Electromagnetic Field

Plasmon is a collective excitation in metals formed through the Coulomb interaction between individual excitations of electron-hole pairs. In many previous studies on the plasmonic response, the role of the longitudinal field has been focused almost exclusively on the light-induced plasmonic phenomena, e.g., hot-carrier generation. In our previous study [Phys. Rev. B 105, 165408 (2022)], we have revealed the significant contribution of the transverse electromagnetic field to connect plasmons and electron-hole pairs in nanostructures based on the self-consistent and nonlocal response theory. In this study, we examine how this contribution appears depending on the system parameters, e.g., length and refractive index. The elucidation of roles of coherent coupling between the collective and individual excitations by the transverse field will lead to the principle of controlling bidirectional energy transfer between the plasmons and electron-hole pairs, which could significantly enhance hot-carrier generation efficiency.Comment: 17 pages, 4 figures, accepted in J. Phys. Soc. Jp

Effects of Radial Inertia and End Friction in Specimen Geometry in Split Hopkinson Pressure Bar Tests : A Computational Study

The split Hopkinson pressure bar (SHPB) technique has been used widely for the impact testing of materials in the strain-rate range from 10(2) to 10(4) s(-1). However, some specific problems still remain mainly concerning the effects of radial inertia and end friction in a cylindrical specimen on the accurate determination of dynamic stress-strain curves of materials. In this study, the basic principle of the SHPB technique is revisited based on energy conservation and some modifications are made considering radial momentum conservation. It is pointed out that the radial inertia and end friction effects are coupled to each other in the SHPB specimen. Computational simulations using the commercial finite element (FE) code ABAQUS/Explicit ver. 6.8 are conducted to check the validity of the modifications for ductile pure aluminum specimens. Both rate-independent and rate-dependent models are adopted for the test material. Simulations are performed by varying two different control parameters: a friction coefficient between the specimen and the pressure bars and a slenderness ratio of the specimen (or thickness to diameter ratio)

Development of an Analyzing System for Student’s Learning Characteristics by Visualization of Learning History

We have developed a system for visualizing students’ learning characteristics within a small learning group based on the learning data accumulated in the individual learning support system In this paper, we developed a program with both a server side and a client side in order to implement it as a Web application This makes it possible for the teachers to display a list of learning histories for all students in the class, analyze and understand the learning characteristics of any student in the classArticleE-Learn: World Conference on E-Learning in Corporate, Government, Healthcare, and Higher Education.2017(1):818-821(2017)conference pape