We briefly review a tension in current amplitudes of cosmological density fluctuations determined by CMB and LSS. Planck satellite recently measured CMB temperature and polarization fluctuations, and determined an amplitude of primordial density fluctuations very precisely. The current amplitude of the fluctuations can be inferred from the primordial one assuming standard ΛCDM cosmological model. On the other hand, LSS (galaxy distribution, weak lensing and cluster abundances) can directly measure the present density fluctuations. However, there is a discrepancy of the amplitudes determined by CMB and LSS. Planck predicts the larger amplitude than LSS. We will briefly report this discrepancy and introduce some possible solutions to this problem. We may need new physics or a modification of dark matter model to solve it.

Emergence of matrix models in the determination of low energy effective action in supersymmetric gauge theory is reviewed, highlighting the three stages of developments that took place in the last twenty some years. Concrete examples collected through this long lasting study tell us that the effective prepotential is to be identified as the suitably defined free energy of a matrix model: F=F.

About 25% of energy density of the universe today is in the form of non-baryonic cold dark matter, and Weakly Interacting Massive Particles (WIMPs) are one of the most promising candidates. Annihilation of WIMPs could produce detectable gamma-ray signal depending on their mass and number density. The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope is sensitive to GeV gamma rays and is suitable for indirect search of WIMP signals. Recent studies of gamma rays in the direction of Galactic center reveal an extended excess emission in 1–10 GeV energies over the standard Galactic diffuse gamma-ray emission. Although the excess can be explained by annihilation of WIMPs with the mass of a few 10s GeV, the spectrum is strongly affected by the uncertainty of the Galactic diffuse emission. No significant gamma-ray excess was found coincident with known dwarf spheroidal galaxies which are known to be dark matter rich and lack of non-thermal astrophysical processes. Instead, WIMP mass less than 100 GeV are excluded by 95% confidence. If the most of the Galactic center excess is not due to WIMP annihilation, more observations by Fermi-LAT with future observations in TeV gamma rays by Cherenkov Telescope Array, will enable us to search for WIMP signal of mass range from 10 GeV up to a few TeV.

The first observation of the light-dressing effect in the laser-assisted elastic electron scattering process, which was predicted more than 30 years ago, is reported. This phenomenon will be of use for probing the ultrafast evolution of the electron density distribution in atoms and molecules.

An electrostatic ion beam trap confines the keV energy ion beam in a finite space using only electrostatic force. This device has a simple structure in which the ions oscillate between the two electrostatic reflectors located on opposite sides. The space between the two reflectors is a field-free region so that the kinetic energy of the ions in this region is equal to their injection energy. Therefore, the device allows us to study interactions of mono-energetic ions with atoms, ions, electrons, and photons. An advantage of the electrostatic ion beam trap is that the electric field for the storage of the ions is independent of the ion mass at a given energy. This opens the possibility of experiments using ion beams of heavier molecular ions, such as cluster ions and biomolecular ions. In this article, we provide an overview of the design and operation of the electrostatic ion beam trap. After this we will present our recent experimental results briefly.