Development of space stable thermal control coatings for use on large space vehicles

The development of a large scale manufacturing method for the production of a stable zinc orthotitanate pigment by means of an oxalate co-precipitation method is examined. Pigments were prepared at various temperatures, and major emphasis was placed on the determination of the important parameters of post-precipitation firing and treatment. A large-scale process for the modification of a glass resin binder was developed and paints were formulated using the binder

Spin solid phases of spin 1 and spin 3/2 antiferromagnets on a cubic lattice

We study spin S=1 and S=3/2 Heisenberg antiferromagnets on a cubic lattice focusing on spin solid states. Using Schwinger boson formulation for spins, we start in a U(1) spin liquid phase proximate to Neel phase and explore possible confining paramagnetic phases as we transition away from the spin liquid by the process of monopole condensation. Electromagnetic duality is used to rewrite the theory in terms of monopoles. For spin 1 we find several candidate phases of which the most natural one is a phase with spins organized into parallel Haldane chains. For spin 3/2 we find that the most natural phase has spins organized into parallel ladders. As a by-product, we also write a Landau theory of the ordering in two special classical frustrated XY models on the cubic lattice, one of which is the fully frustrated XY model. In a particular limit our approach maps to a dimer model with 2S dimers coming out of every site, and we find the same spin solid phases in this regime as well.Comment: 15 pages, 8 figure

Comment on ``Confirmation of the Sigma Meson''

We comment on the recent paper by N.A. Tornqvist and M. Roos published in Phys. Rev. Lett. 76, 1575 (1996).Comment: 3 pages (LaTeX), 1 PostScript Figur

A trapped surface in the higher-dimensional self-similar Vaidya spacetime

We investigate a trapped surface and naked singularity in a $D$-dimensional Vaidya spacetime with a self-similar mass function. A trapped surface is defined as a closed spacelike $(D-2)$-surface which has negative both null expansions. There is no trapped surface in the Minkowski spacetime. However, in a four-dimensional self-similar Vaidya spacetime, Bengtsson and Senovilla considered non-spherical trapped surfaces and showed that a trapped surface can penetrate into a flat region, if and only if the mass function rises fast enough [I. Bengtsson and J. M. M. Senovilla, Phys. Rev. D \textbf{79}, 024027 (2009).]. We apply this result to a $D$-dimensional spacetime motivated by the context of large extra dimensions or TeV-scale gravity. In this paper, similarly to Bengtsson and Senovilla's study, we match four types of $(D-2)$-surfaces and show that a trapped surface extended into the flat region can be constructed in the $D$-dimensional Vaidya spacetime, if the increasing rate of the mass function is greater than 0.4628. Moreover, we show that the maximum radius of the trapped surface constructed here approaches the Schwarzschild-Tangherlini radius in the large $D$ limit. Also, we show that there is no naked singularity, if the spacetime has the trapped surface constructed here.Comment: 13 pages, 5 figure

Stable White Coatings

In a previous research program for the Jet Propulsion- Laboratory, extensive studies led to the development and specifications of three zinc oxide-pigmented thermal-control coatings. The principal objectives of this program are: improvement of the three paints (as engineering materials), determination of the validity of our accelerated space-simulation testing, and continuation of the zinc oxide photolysis studies begun in the preceding program. Specific tasks that are discussed include: improvement of potassium silicate coatings as engineering materials and elucidation of their storage and handling problems; improvement of methyl silicone coatings as engineering materials; studies of zinc oxide photolysis to establish reasons for the observed stability of zinc oxide; and determination of space-simulation parameters such as long-term stability (to 8000 ESH), effect of coating surface temperature on the rate of degradation, and validity of accelerated testing (by reciprocity and wavelength dependency studies)

Development of space-stable thermal-control coatings /paints with low solar absorptance/ emittance ratios/ triannual report, 20 jun. - 20 oct. 1964

Development of space stable thermal control coating

Fate of Vector Dominance in the Effective Field Theory

We reveal the full phase structure of the effective field theory for QCD, based on the hidden local symmetry (HLS) through the one-loop renormalization group equation including quadratic divergences. We then show that vector dominance (VD) is not a sacred discipline of the effective field theory but rather an accidental phenomenon peculiar to three-flavored QCD. In particular, the chiral symmetry restoration in HLS model takes place in a wide phase boundary surface, on which the VD is realized nowhere. This suggests that VD may not be valid for chiral symmetry restoration in hot and/or dense QCD.Comment: 4 pages, 3 figures. One reference added. Minor modification to shorten the manuscript. This is the version to appear in Physical Review Letter

Holographic QCD Integrated back to Hidden Local Symmetry

We develop a previously proposed gauge-invariant method to integrate out infinite tower of Kaluza-Klein (KK) modes of vector and axialvector mesons in a class of models of holographic QCD (HQCD). The HQCD is reduced by our method to the chiral perturbation theory with the hidden local symmetry (HLS) having only the lowest KK mode identified as the HLS gauge boson. We take the Sakai-Sugimoto model as a concrete HQCD, and completely determine the ${\cal O} (p^4)$ terms as well as the ${\cal O}(p^2)$ terms from the DBI part and the anomaly-related (intrinsic parity odd) gauge-invariant terms from the CS part. Effects of higher KK modes are fully included in these terms. To demonstrate power of our method, we compute momentum-dependences of several form factors such as the pion electromagnetic form factors, the $\pi^0$-$\gamma$ and $\omega$-$\pi^0$ transition form factors compared with experiment, which was not achieved before due to complication to handle infinite sums. We also study other anomaly-related quantities like $\gamma^*$-$\pi^0$-$\pi^+$-$\pi^-$ and $\omega$-$\pi^0$-$\pi^+$-$\pi^-$ vertex functions.Comment: 4 eps figures, 37 pages, latex, typos fixed; some discussions and references added; fig.4 replace