Momentum dependence of the energy gap in the superconducting state of optimally doped Bi2(Sr,R)2CuOy (R=La and Eu)

The energy gap of optimally doped Bi2(Sr,R)2CuOy (R=La and Eu) was probed by angle resolved photoemission spectroscopy (ARPES) using a vacuum ultraviolet laser (photon energy 6.994 eV) or He I resonance line (21.218 eV) as photon source. The results show that the gap around the node at sufficiently low temperatures can be well described by a monotonic d-wave gap function for both samples and the gap of the R=La sample is larger reflecting the higher Tc. However, an abrupt deviation from the d-wave gap function and an opposite R dependence for the gap size were observed around the antinode, which represent a clear disentanglement between the antinodal pseudogap and the nodal superconducting gap.Comment: Submitted as the proceedings of LT2

Coupling Unifications in Gauge-Higgs Unified Orbifold Models

Supersymmetric gauge theories, in higher dimensions compactified in an orbifold, give a natural framework to unify the gauge bosons, Higgs fields and even the matter fields in a single multiplet of the unifying gauge symmetry. The extra dimensions and the supersymmetry are the two key ingredients for such an unification. In this work, we investigate various scenarios for the unification of the three gauge couplings, and the Yukawa couplings in the Minimal Supersymmetric Standard Model (MSSM), as well as the trilinear Higgs couplings \lambda and \kappa of the Non-Minimal Supersymmetric Standard Model (NMSSM). We present an SU(8) model in six dimensions with N=2 supersymmetry, compactified in a T^2/Z_6 orbifold which unifies the three gauge couplings with \lambda and \kappa of NMSSM. Then, we present an SU(9) model in 6D, which, in addition, includes partial unification of Yukawa couplings, either for the up-type (top quark and Dirac tau-neutrino) or down-type (bottom quark and tau lepton). We also study the phenomenological implications of these various unification scenarios using the appropriate renormalization group equations, and show that such unification works very well with the measured low energy values of the couplings. The predicted upper bounds for the lightest neutral Higgs boson mass in our model is higher than those in MSSM, but lower that those in the general NMSSM (where the couplings \lambda and \kappa are arbitrary). Some of the predictions of our models can be tested in the upcoming Large Hadron Collider.Comment: 29 pages, 4 figure

Spatial Distributions of Cold and Warm Interstellar Dust in M101 Resolved with AKARI/Far-Infrared Surveyor (FIS)

The nearby face-on spiral galaxy M101 has been observed with the Far-Infrared Surveyor (FIS) onboard AKARI. The far-infrared four-band images reveal fine spatial structures of M101, which include global spiral patterns, giant HII regions embedded in outer spiral arms, and a bar-like feature crossing the center. The spectral energy distribution of the whole galaxy shows the presence of the cold dust component (18 K) in addition to the warm dust component (55 K). The distribution of the cold dust is mostly concentrated near the center, and exhibits smoothly distributed over the entire extent of the galaxy, whereas the distribution of the warm dust indicates some correlation with the spiral arms, and has spotty structures such as four distinctive bright spots in the outer disk in addition to a bar-like feature near the center tracing the CO intensity map. The star-formation activity of the giant HII regions that spatially correspond to the former bright spots is found to be significantly higher than that of the rest of the galaxy. The latter warm dust distribution implies that there are significant star-formation activities in the entire bar filled with molecular clouds. Unlike our Galaxy, M101 is a peculiar normal galaxy with extraordinary active star-forming regions.Comment: 18 pages, 9 figures, accepted for publication in PASJ AKARI special issu

Retrieval Properties of Hopfield and Correlated Attractors in an Associative Memory Model

We examine a previouly introduced attractor neural network model that explains the persistent activities of neurons in the anterior ventral temporal cortex of the brain. In this model, the coexistence of several attractors including correlated attractors was reported in the cases of finite and infinite loading. In this paper, by means of a statistical mechanical method, we study the statics and dynamics of the model in both finite and extensive loading, mainly focusing on the retrieval properties of the Hopfield and correlated attractors. In the extensive loading case, we derive the evolution equations by the dynamical replica theory. We found several characteristic temporal behaviours, both in the finite and extensive loading cases. The theoretical results were confirmed by numerical simulations.Comment: 12 pages, 7 figure

A new ultra high energy gamma ray telescope at Ohya mine

The search for ultra high energy gamma rays coming from point sources is one of the main experimental aims. A fast air shower timing system was constructed at ICRR for the study of the angular resolution of the system and operated approximately half a year. The characteristics of the surface array of Ohya air shower telescope is described