Invariances and Equations of Motion in Double Field Theory

We investigate the full set of equations of motion in double field theory and discuss their O(D,D) symmetry and gauge transformation properties. We obtain a Ricci-like tensor, its associated Bianchi identities, and relate our results to those with a generalized metric formulation.Comment: 24 page

Green-Schwarz Formulation of Self-Dual Superstring

The self-dual superstring has been described previously in a Neveu-Schwarz-Ramond formulation with local N=2 or 4 world-sheet supersymmetry. We present a Green-Schwarz-type formulation, with manifest spacetime supersymmetry.Comment: 11 pg., (uuencoded dvi file) ITP-SB-92-5

Thermalization via Heat Radiation of an Individual Object Thinner than the Thermal Wavelength

Modeling and investigating the thermalization of microscopic objects with arbitrary shape from first principles is of fundamental interest and may lead to technical applications. Here, we study, over a large temperature range, the thermalization dynamics due to far-field heat radiation of an individual, deterministically produced silica fiber with a predetermined shape and a diameter smaller than the thermal wavelength. The temperature change of the subwavelength-diameter fiber is determined through a measurement of its optical path length in conjunction with an ab initio thermodynamic model of the fiber structure. Our results show excellent agreement with a theoretical model that considers heat radiation as a volumetric effect and takes the emitter shape and size relative to the emission wavelength into account

Broadband electromagnetic response and ultrafast dynamics of few-layer epitaxial graphene

We study the broadband optical conductivity and ultrafast carrier dynamics of epitaxial graphene in the few-layer limit. Equilibrium spectra of nominally buffer, monolayer, and multilayer graphene exhibit significant terahertz and near-infrared absorption, consistent with a model of intra- and interband transitions in a dense Dirac electron plasma. Non-equilibrium terahertz transmission changes after photoexcitation are shown to be dominated by excess hole carriers, with a 1.2-ps mono-exponential decay that reflects the minority-carrier recombination time.Comment: 4 pages, 3 figures, final versio

Mass Upper Bounds for Over 50 Kepler Planets Using Low-S/N Transit Timing Variations

Prospects for expanding the available mass measurements of the Kepler sample are limited. Planet masses have typically been inferred via radial velocity (RV) measurements of the host star or time-series modeling of transit timing variations (TTVs) in multiplanet systems; however, the majority of Kepler hosts are too dim for RV follow-up, and only a select number of systems have strong enough TTVs for time-series modeling. Here, we develop a method of constraining planet mass in multiplanet systems using low signal-to-noise ratio (S/N) TTVs. For a sample of 175 planets in 79 multiplanet systems from the California-Kepler Survey, we infer posteriors on planet mass using publicly available TTV time-series from Kepler. For 53 planets ($>30\%$ of our sample), low-S/N TTVs yield informative upper bounds on planet mass, i.e., the mass constraint strongly deviates from the prior on mass and yields a physically reasonable bulk composition. For 25 small planets, low-S/N TTVs favor volatile-rich compositions. Where available, low-S/N TTV-based mass constraints are consistent with RV-derived masses. TTV time-series are publicly available for each Kepler planet, and the compactness of Kepler systems makes TTV-based constraints informative for a substantial fraction of multiplanet systems. Leveraging low-S/N TTVs offers a valuable path toward increasing the available mass constraints of the Kepler sample.Comment: 18 pages, accepted to A

Model for SU(3) vacuum degeneracy using light-cone coordinates

Working in light-cone coordinates, we study the zero-modes and the vacuum in a 2+1 dimensional SU(3) gauge model. Considering the fields as independent of the tranverse variables, we dimensionally reduce this model to 1+1 dimensions. After introducing an appropriate su(3) basis and gauge conditions, we extract an adjoint field from the model. Quantization of this adjoint field and field equations lead to two constrained and two dynamical zero-modes. We link the dynamical zero-modes to the vacuum by writing down a Schrodinger equation and prove the non-degeneracy of the SU(3) vacuum provided that we neglect the contribution of constrained zero-modes.Comment: 22 pages, 5 figure

Commensurability effects in superconducting Nb films with quasiperiodic pinning arrays

We study experimentally the critical depinning current Ic versus applied magnetic field B in Nb thin films which contain 2D arrays of circular antidots placed on the nodes of quasiperiodic (QP) fivefold Penrose lattices. Close to the transition temperature Tc we observe matching of the vortex lattice with the QP pinning array, confirming essential features in the Ic(B) patterns as predicted by Misko et al. [Phys. Rev. Lett, vol.95, 177007 (2005)]. We find a significant enhancement in Ic(B) for QP pinning arrays in comparison to Ic in samples with randomly distributed antidots or no antidots.Comment: 4 pages, 3 figure

More Discriminants with the Brezing-Weng Method

The Brezing-Weng method is a general framework to generate families of pairing-friendly elliptic curves. Here, we introduce an improvement which can be used to generate more curves with larger discriminants. Apart from the number of curves this yields, it provides an easy way to avoid endomorphism rings with small class number