Consistency Conditions of the Faddeev-Niemi-Periwal Ansatz for the SU(N) Gauge Field

The consistency condition of the Faddeev-Niemi ansatz for the gauge-fixed massless SU(2) gauge field is discussed. The generality of the ansatz is demonstrated by obtaining a sufficient condition for the existence of the three-component field introduced by Faddeev and Niemi. It is also shown that the consistency conditions determine this three-component field as a functional of two arbitrary functions. The consistency conditions corresponding to the Periwal ansatz for the SU(N) gauge field with N larger than 2 are also obtained. It is shown that the gauge field obeying the Periwal ansatz must satisfy extra (N-1)(N-2)/2 conditions.Comment: PTP Tex, 15 pages, Eq.(3.18) inserte

Non-Abelian Stokes Theorem for Loop Variables Associated with Nontrivial Loops

The non-Abelian Stokes theorem for loop variables associated with nontrivial loops (knots and links) is derived. It is shown that a loop variable is in general different from unity even if the field strength vanishes everywhere on the surface surrounded by the loop.Comment: 18 pages,10 Postscript figures, PTP Tex, Journal-ref adde

Renormalization-group and numerical analysis of a noisy Kuramoto-Sivashinsky equation in 1+1 dimensions

The long-wavelength properties of a noisy Kuramoto-Sivashinsky (KS) equation in 1+1 dimensions are investigated by use of the dynamic renormalization group (RG) and direct numerical simulations. It is shown that the noisy KS equation is in the same universality class as the Kardar-Parisi-Zhang (KPZ) equation in the sense that they have scale invariant solutions with the same scaling exponents in the long-wavelength limit. The RG analysis reveals that the RG flow for the parameters of the noisy KS equation rapidly approach the KPZ fixed point with increasing the strength of the noise. This is supplemented by the numerical simulations of the KS equation with a stochastic noise, in which the scaling behavior of the KPZ equation can be easily observed even in the moderate system size and time.Comment: 12pages, 7figure

Field-Effect Transistor on SrTiO3 with sputtered Al2O3 Gate Insulator

A field-effect transistor that employs a perovskite-type SrTiO3 single crystal as the semiconducting channel is revealed to function as n-type accumulation-mode device with characteristics similar to that of organic FET's. The device was fabricated at room temperature by sputter-deposition of amorphous Al2O3 films as a gate insulator on the SrTiO3 substrate. The field-effect(FE) mobility is 0.1cm2/Vs and on-off ratio exceeds 100 at room temperature. The temperature dependence of the FE mobility down to 2K shows a thermal-activation-type behavior with an activation energy of 0.6eV

On the nature of the X-ray absorption in the Seyfert 2 galaxy NGC 4507

We present results of the ASCA observation of the Seyfert 2 galaxy NGC 4507. The 0.5-10 keV spectrum is rather complex and consists of several components: (1) a hard X-ray power law heavily absorbed by a column density of about 3 10^23 cm^-2, (2) a narrow Fe Kalpha line at 6.4 keV, (3) soft continuum emission well above the extrapolation of the absorbed hard power law, (4) a narrow emission line at about 0.9 keV. The line energy, consistent with highly ionized Neon (NeIX), may indicate that the soft X-ray emission derives from a combination of resonant scattering and fluorescence in a photoionized gas. Some contribution to the soft X-ray spectrum from thermal emission, as a blend of Fe L lines, by a starburst component in the host galaxy cannot be ruled out with the present data.Comment: 8 pages, LateX, 5 figures (included). Uses mn.sty and epsfig.sty. To appear in MNRA

Self-dual Einstein Spaces, Heavenly Metrics and Twistors

Four-dimensional quaternion-Kahler metrics, or equivalently self-dual Einstein spaces M, are known to be encoded locally into one real function h subject to Przanowski's Heavenly equation. We elucidate the relation between this description and the usual twistor description for quaternion-Kahler spaces. In particular, we show that the same space M can be described by infinitely many different solutions h, associated to different complex (local) submanifolds on the twistor space, and therefore to different (local) integrable complex structures on M. We also study quaternion-Kahler deformations of M and, in the special case where M has a Killing vector field, show that the corresponding variations of h are related to eigenmodes of the conformal Laplacian on M. We exemplify our findings on the four-sphere S^4, the hyperbolic plane H^4 and on the "universal hypermultiplet", i.e. the hypermultiplet moduli space in type IIA string compactified on a rigid Calabi-Yau threefold.Comment: 44 pages, 1 figure; misprints correcte

Ground-state electric quadrupole moment of 31Al

Ground-state electric quadrupole moment of 31Al (I =5/2+, T_1/2 = 644(25) ms) has been measured by means of the beta-NMR spectroscopy using a spin-polarized 31Al beam produced in the projectile fragmentation reaction. The obtained Q moment, |Q_exp(31Al)| = 112(32)emb, are in agreement with conventional shell model calculations within the sd valence space. Previous result on the magnetic moment also supports the validity of the sd model in this isotope, and thus it is concluded that 31Al is located outside of the island of inversion.Comment: 5 page

Role of charge carriers for ferromagnetism in cobalt-doped rutile TiO2

Electric and magnetic properties of a high temperature ferromagnetic oxide semiconductor, cobalt-doped rutile TiO2, are summarized. The cobalt-doped rutile TiO2 epitaxial thin films with different electron densities and cobalt contents were grown on r-sapphire substrates with laser molecular beam epitaxy. Results of magnetization, magnetic circular dichroism, and anomalous Hall effect measurements were examined for samples with systematically varied electron densities and cobalt contents. The samples with high electron densities and cobalt contents show the high temperature ferromagnetism, suggesting that charge carriers induce the ferromagnetism.Comment: 14 pages, 12 figure

Coupled Nonlinear Schr\"{o}dinger equation and Toda equation (the Root of Integrability)

We consider the relation between the discrete coupled nonlinear Schr\"{o}dinger equation and Toda equation. Introducing complex times we can show the intergability of the discrete coupled nonlinear Schr\"{o}dinger equation. In the same way we can show the integrability in coupled case of dark and bright equations. Using this method we obtain several integrable equations.Comment: 11 pages, LateX, to apper in J. Phys. Soc. Jpn. Vol. 66, No