A Novel Photonic Material for Designing Arbitrarily Shaped Waveguides in Two Dimensions

We investigate numerically optical properties of novel two-dimensional photonic materials where parallel dielectric rods are randomly placed with the restriction that the distance between rods is larger than a certain value. A large complete photonic gap (PG) is found when rods have sufficient density and dielectric contrast. Our result shows that neither long-range nor short-range order is an essential prerequisite to the formation of PGs. A universal principle is proposed for designing arbitrarily shaped waveguides, where waveguides are fenced with side walls of periodic rods and surrounded by the novel photonic materials. We observe highly efficient transmission of light for various waveguides. Due to structural uniformity, the novel photonic materials are best suited for filling up the outer region of waveguides of arbitrary shape and dimension comparable with the wavelength.Comment: 4 figure

Off-diagonal Gluon Mass Generation and Infrared Abelian Dominance in Maximally Abelian Gauge in SU(3) Lattice QCD

In SU(3) lattice QCD formalism, we propose a method to extract gauge fields from link-variables analytically. With this method, we perform the first study on effective mass generation of off-diagonal gluons and infrared Abelian dominance in the maximally Abelian (MA) gauge in the SU(3) case. Using SU(3) lattice QCD, we investigate the propagator and the effective mass of the gluon fields in the MA gauge with U(1)_3 \timesU(1)_8 Landau gauge fixing. The Monte Carlo simulation is performed on $16^4$ at $\beta$=5.7, 5.8 and 6.0 at the quenched level. The off-diagonal gluons behave as massive vector bosons with the approximate effective mass $M_{\mathrm{off}} \simeq 1.1-1.2\mathrm{GeV}$ in the region of $r =0.3-0.8$fm, and the propagation is limited within a short range, while the propagation of diagonal gluons remains even in a large range. In this way, infrared Abelian dominance is shown in terms of short-range propagation of off-diagonal gluons. Furthermore, we investigate the functional form of the off-diagonal gluon propagator. The functional form is well described by the four-dimensional Euclidean Yukawa-type function $e^{-m_{\rm off}r}/r$ with $m_{\rm off} \simeq 1.3-1.4\mathrm{GeV}$ for $r = 0.1- 0.8$ fm. This also indicates that the spectral function of off-diagonal gluons has the negative-value region

Collisional stability of localized Yb(3P2{}^3\mathrm{P}_2) atoms immersed in a Fermi sea of Li

We establish an experimental method for a detailed investigation of inelastic collisional properties between ytterbium (Yb) in the metastable ${}^3\mathrm{P}_2$ state and ground state lithium (Li). By combining an optical lattice and a direct excitation to the ${}^3\mathrm{P}_2$ state we achieve high selectivity on the collisional partners. Using this method we determine inelastic loss coefficients in collisions between $^{174}$Yb(${}^3\mathrm{P}_2$) with magnetic sublevels of $m_J=0$ and $-2$ and ground state $^6$Li to be $(4.4\pm0.3)\times10^{-11}~\mathrm{cm}^3/\mathrm{s}$ and $(4.7\pm0.8)\times10^{-11}~\mathrm{cm}^3/\mathrm{s}$, respectively. Absence of spin changing processes in Yb(${}^3\mathrm{P}_2$)-Li inelastic collisions at low magnetic fields is confirmed by inelastic loss measurements on the $m_J=0$ state. We also demonstrate that our method allows us to look into loss processes in few-body systems separately.Comment: 12 pages, 7 figure

Morphological and Structural Changes in Microcrystalline Cellulose from OPEFB by Mechanical Grinding

Microcrystalline cellulose derived from oil palm empty fruit bunch (OPEFB) was grinded in planetary ball mill with dry state (without solvent) and solvent-assisted (ethanol and acetone). The effect of dry state and solvent-assisted on morphological and structural changes of microcrystalline cellulose were investigated. The structure changes, including particle size, powder morphology, crystalline structure, and molecular structure during the mechanical grinding were investigated by Laser Diffraction Particle Size Analyzer, SEM, XRD and FT-IR, respectively. The original fibrous microcrystalline cellulose was changed into irregular shape with finer micronized particles by dry state and solvent-assisted. SEM results showed that solvent-assisted significantly prevented the agglomeration phenomena during the grinding process, compared to dry state. The crystallinity after 4h solvent-assisted grinding showed fairly low crystallinity, while amorphous characteristic was observed with dry state grinding. The solvent-assisted led the hydrophilic parts of microcrystalline cellulose become stiff during the grinding that might be less deformed, leading to a fairly retain in crystallinity. The finer micronized particles were obtained under acetone-assisted and its crystallinity was fairly kept. XRD results indicated that crystalline form of origin microcrystalline was not changed by mechanical grinding

Prospect for Future MeV Gamma-ray Active Galactic Nuclei Population Studies

While the X-ray, GeV gamma-ray, and TeV gamma-ray skies have been extensively studied, the MeV gamma-ray sky is not well investigated after the Imaging Compton Telescope (COMPTEL) scanned the sky about two decades ago. In this paper, we investigate prospects for active galactic nuclei population studies with future MeV gamma-ray missions using recent spectral models and luminosity functions of Seyfert and flat spectrum radio quasars (FSRQs). Both of them are plausible candidates as the origins of the cosmic MeV gamma-ray background. If the cosmic MeV gamma-ray background radiation is dominated by non-thermal emission from Seyferts, the sensitivity of 10^-12 erg cm^-2 s^-1 is required to detect several hundred Seyferts in the entire sky. If FSRQs make up the cosmic MeV gamma-ray background, the sensitivity of ~4 x 10^-12 erg cm^-2 s^-1 is required to detect several hundred FSRQs following the recent FSRQ X-ray luminosity function. However, based on the latest FSRQ gamma-ray luminosity function, with which FSRQs can explain up to ~30% of the MeV background, we can expect several hundred FSRQs even with the sensitivity of 10^-11 erg cm^-2 s^-1 which is almost the same as the sensitivity goal of the next generation MeV telescopes.Comment: 9 pages, 5 figures, accepted for publication in PAS

Fermi surface with Dirac fermions in CaFeAsF determined via quantum oscillation measurements

Despite the fact that 1111-type iron arsenides hold the record transition temperature of iron-based superconductors, their electronic structures have not been studied much because of the lack of high-quality single crystals. In this study, we completely determine the Fermi surface in the antiferromagnetic state of CaFeAsF, a 1111 iron-arsenide parent compound, by performing quantum oscillation measurements and band-structure calculations. The determined Fermi surface consists of a symmetry-related pair of Dirac electron cylinders and a normal hole cylinder. From analyses of quantum-oscillation phases, we demonstrate that the electron cylinders carry a nontrivial Berry phase $\pi$. The carrier density is of the order of 10$^{-3}$ per Fe. This unusual metallic state with the extremely small carrier density is a consequence of the previously discussed topological feature of the band structure which prevents the antiferromagnetic gap from being a full gap. We also report a nearly linear-in-$B$ magnetoresistance and an anomalous resistivity increase above about 30 T for $B \parallel c$, the latter of which is likely related to the quantum limit of the electron orbit. Intriguingly, the electrical resistivity exhibits a nonmetallic temperature dependence in the paramagnetic tetragonal phase ($T >$ 118 K), which may suggest an incoherent state. Our study provides a detailed knowledge of the Fermi surface in the antiferromagnetic state of 1111 parent compounds and moreover opens up a new possibility to explore Dirac-fermion physics in those compounds.Comment: 11 pages, 7 figures, 1 tabl

Fabrication of submicron La2−x_{2-x}Srx_{x}CuO4_{4} intrinsic Josephson junction stacks

Intrinsic Josephson junction (IJJ) stacks of cuprate superconductors have potential to be implemented as intrinsic phase qubits working at relatively high temperatures. We report success in fabricating submicron La$_{2-x}$Sr$_{x}$CuO$_{4}$ (LSCO) IJJ stacks carved out of single crystals. We also show a new fabrication method in which argon ion etching is performed after focused ion beam etching. As a result, we obtained an LSCO IJJ stack in which resistive multi-branches appeared. It may be possible to control the number of stacked IJJs with an accuracy of a single IJJ by developing this method.Comment: 5 pages, 6 figure

Phase effects from the general neutrino Yukawa matrix on lepton flavor violation

We examine contributions from Majorana phases to lepton flavor violating processes in the framework of the minimal supersymmetric standard model with heavy right-handed neutrinos. All phases in the complex neutrino Yukawa matrix are taken into account in our study. We find that in the scenario with universal soft-breaking terms sizable phase effects can appear on the lepton flavor violating processes such as $\mu \to e \gamma$, $\tau \to e \gamma$, and $\tau \to \mu \gamma$. In particular, the branching ratio of $\mu \to e \gamma$ can be considerably enhanced due to the Majorana phases, so that it can be much greater than that of $\tau \to \mu \gamma$.Comment: 14 pages, 4 eps figures, revtex

One-Loop Corrections to the S and T Parameters in a Three Site Higgsless Model

In this paper we compute the the one-loop chiral logarithmic corrections to the S and T parameters in a highly deconstructed Higgsless model with only three sites. In addition to the electroweak gauge bosons, this model contains a single extra triplet of vector states (which we denote \rho^{\pm} and \rho^0), rather than an infinite tower of "KK" modes. We compute the corrections to S and T in 'tHooft-Feynman gauge, including the ghost, unphysical Goldstone-boson, and appropriate "pinch" contributions required to obtain gauge-invariant results for the one-loop self-energy functions. We demonstrate that the chiral-logarithmic corrections naturally separate into two parts, a model-independent part arising from scaling below the \rho mass, which has the same form as the large Higgs-mass dependence of the S or T parameter in the standard model, and a second model-dependent contribution arising from scaling between the \rho mass and the cutoff of the model. The form of the universal part of the one-loop result allows us to correctly interpret the phenomenologically derived limits on the S and T parameters (which depend on a "reference" Higgs-boson mass) in this three-site Higgsless model. Higgsless models may be viewed as dual to models of dynamical symmetry breaking akin to "walking technicolor", and in these terms our calculation is the first to compute the subleading 1/N corrections to the S and T parameters. We also discuss the reduction of the model to the ``two-site'' model, which is the usual electroweak chiral lagrangian, noting the ``non-decoupling'' contributions present in the limit as M_\rho goes to infinity.Comment: 58 pages; uses JHEP and axodraw. Extensively corrected to incorporate consistent perturbative expansion, additional pinch contributions, and running of delocalization parameter. Footnotes adde