Searching for Axino-Like Particle at Fixed Target Experiments

We investigate the detectability of axino-like particle, which is defined as a supersymmetric partner of axion-like particle and can be a good candidate for dark matter in our Universe. Especially, we consider the fixed target experiments to search for the light axino-like particle with a neutralino as the next-to-lightest supersymmetric particle. We calculate the production and decay rate of neutralinos and the consequent number of events (such as photons and charged leptons) that are produced when the neutralinos decay to the axino-like particles.Comment: 10 pages, 7 figures, Published in Physics of the Dark Univers

Hirota bilinear forms with 2-toroidal symmetry

In this note, we compute Hirota bilinear forms arising from both homogeneous and principal realization of vertex representations of 2-toroidal Lie algebras of type $A_l, D_l, E_l$.Comment: 11 pages, AMS-latex fil

Investigation by Imaging Mass Spectrometry of Biomarker Candidates for Aging in the Hair Cortex

BACKGROUND: Human hair is one of the essential components that define appearance and is a useful source of samples for non-invasive biomonitoring. We describe a novel application of imaging mass spectrometry (IMS) of hair biomolecules for advanced molecular characterization and a better understanding of hair aging. As a cosmetic and biomedical application, molecules whose levels in hair altered with aging were comprehensively investigated. METHODS: Human hair was collected from 15 young (20±5 years old) and 15 older (50±5 years old) volunteers. Matrix-free laser desorption/ionization IMS was used to visualize molecular distribution in the hair sections. Hair-specific ions displaying a significant difference in the intensities between the 2 age groups were extracted as candidate markers for aging. Tissue localization of the molecules and alterations in their levels in the cortex and medulla in the young and old groups were determined. RESULTS: Among the 31 molecules detected specifically in hair sections, 2--one at m/z 153.00, tentatively assigned to be dihydrouracil, and the other at m/z 207.04, identified to be 3,4-dihydroxymandelic acid (DHMA)--exhibited a higher signal intensity in the young group than in the old, and 1 molecule at m/z 164.00, presumed to be O-phosphoethanolamine, displayed a higher intensity in the old group. Among the 3, putative O-phosphoethanolamine showed a cortex-specific distribution. The 3 molecules in cortex presented the same pattern of alteration in signal intensity with aging, whereas those in medulla did not exhibit significant alteration. CONCLUSION: Three molecules whose levels in hair altered with age were extracted. While they are all possible markers for aging, putative dihydrouracil and DHMA, are also suspected to play a role in maintaining hair properties and could be targets for cosmetic supplementation. Mapping of ion localization in hair by IMS is a powerful method to extract biomolecules in specified regions and determine their tissue distribution

Observation of magnetic domains by means of non-resonant magnetic x-ray diffraction

There has been a strong demand for observing magnetic domains inside materials for a long time, because these magnetic microstructures are definitely responsible for superior magnetic properties in various functional magnetic materials, such as Nd-Fe-B permanent magnets and recent highly efficient electrical steel. However, major techniques for magnetic domain observation, such as mageto-optical Kerr effect (MOKE) microscopy and x-ray magnetic circular dichroism (XMCD) microscopy in the soft x-ray region, are sensitive to the surface magnetic microstructures and it is not easy to obtain information of magnetic domains well below the sample surface. Accordingly, the development of bulk sensitive magnetic microscopy is a very active research area recently. Non-resonant magnetic x-ray diffraction (NRMXRD) is a candidate for such three-dimensional magnetic microscopy. A small focus size less than 1 μm can be easily achieved by using synchrotron radiation. A long penetration length more than 100 μm is obtained by using high energy x-rays. A drawback is low magnetic contrast in the order of a few tenths of percent for high energy x-rays. In principle, the magnetic contrast in NRMXRD increases with increasing the total polarization of incident x-rays. In this study, we employ a channel-cut linear polarizer as a device that improves incident linear polarization and experimentally examine enhancement of the magnetic contrast. NRMXRD is a phenomenon that the intensity diffracted at the scattering angle 90° from ferromagnets depends on the helicity of the incident elliptically polarized x-rays. Literally, the process is non-resonant, hence arbitrary high-energy x-rays can be used. Experiments were carried out at the beamlines BL22XU and BL11XU in SPring-8. The energies of the incident x-rays were 8.7 keV, 13 keV, 17.3 keV and 26 keV. In order to increase the incident linear polarization, we used Si(110), Si(111), Ge(110) and Si(100) channel-cut linear polarizers. Elliptically polarized x-rays were generated by using a 500 μm-thick diamond phase plate. The sample was an iron single crystal and an electrical steel sheet. At 8.7 keV and 13 keV, we successfully observed enhancement of the magnetic contrast. However, at 17.3 keV and 26 keV, enhancement was very small. It seems that it is difficult to achieve high magnetic contrast in NRMXRD for high energy x-rays using channel-cut linear polarizers.4th QST International Symposium -Innovation from Quantum Materials Science

Feasibility Study of Magnetic-Domain Observation by Means of Non-Resonant Magnetic X-Ray Diffraction

Although the observation of magnetic domains well below the surface of a sample appears to be relatively easy, in reality, magnetic domains inside metallic samples have not been investigated in detail due to a lack of adequate techniques. Non-resonant magnetic X-ray diffraction (NRMXRD) is a candidate for such 3-D magnetic microscopy. A relatively small focus size of less than 100 nm and a relatively long attenuation length of more than 100 μm can be obtained by using high-energy synchrotron X-rays. However, NRMXRD has a disadvantage in that the magnetic contrast is low. It is known that the magnetic contrast in NRMXRD increases with increasing the total polarization of the incident X-rays. In this feasibility study, we carried out NRMXRD experiments on a metallic iron sample to examine whether the magnetic contrast can be sufficiently enhanced even for high-energy X-rays