Superembeddings, Non-Linear Supersymmetry and 5-branes

We examine general properties of superembeddings, i.e., embeddings of supermanifolds into supermanifolds. The connection between an embedding procedure and the method of non-linearly realised supersymmetry is clarified, and we demonstrate how the latter arises as a special case of the former. As an illustration, the super-5-brane in 7 dimensions, containing a self-dual 3-form world-volume field strength, is formulated in both languages, and provides an example of a model where the embedding condition does not suffice to put the theory on-shell.Comment: plain tex, 28 p

The Self-Dual String and Anomalies in the M5-brane

We study the anomalies of a charge $Q_2$ self-dual string solution in the Coulomb branch of $Q_5$ M5-branes. Cancellation of these anomalies allows us to determine the anomaly of the zero-modes on the self-dual string and their scaling with $Q_2$ and $Q_5$. The dimensional reduction of the five-brane anomalous couplings then lead to certain anomalous couplings for D-branes.Comment: 13 pages, Harvmac, refs adde

On the equivalence of bound state solutions

In this paper we show the equivalence of various (non-threshold) bound state solutions of branes, or equivalently branes in background potentials, in ten- and eleven-dimensional supergravity. We compare solutions obtained in two very different ways. One method uses a zero mode analysis to make an Ansatz which makes it possible to solve the full non-linear supergravity equations. The other method utilises T-duality techniques to turn on the fields on the brane. To be specific, in eleven dimensions we show the equivalence for the (M2,M5) bound state, or equivalently an M5-brane in a C_3 field, where we also consider the (MW,M2,M2',M5) solution, which can be obtained from the (M2,M5) bound state by a boost. In ten dimensions we show the equivalence for the ((F,D1),D3) bound state as well as the bound states of (p,q) 5-branes with lower dimensional branes in type IIB, corresponding to D3-branes in B_2 and C_2 fields and (p,q) 5-branes in B_2, C_2 and C_4 fields. We also comment on the recently proposed V-duality related to infinitesimally boosted solutions.Comment: 19 pages, LaTe

Dirac equation for the supermembrane in a background with fluxes from a component description of the D=11 supergravity-supermembrane interacting system

We present a simple derivation of the 'Dirac' equation for the supermembrane fermionic field in a D=11 supergravity background with fluxes by using a complete but gauge-fixed description of the supergravity-supermembrane interacting system previously developed. We also discuss the contributions linear in the supermembrane fermions -the Goldstone fields for the local supersymmetry spontaneously broken by the superbrane- to the field equations of the supergravity-supermembrane interacting system. The approach could also be applied to more complicated dynamical systems such as those involving the M5-brane and the D=10 Dirichlet branes.Comment: 1+22 pages, JHEP style. v2: cosmetic changes and references added to conform to the JHEP published versio

Efficient out-coupling and beaming of Tamm optical states via surface plasmon polariton excitation

We present evidence of optical Tamm states to surface plasmon polariton (SPP) coupling. We experimentally demonstrate that for a Bragg stack with a thin metal layer on the surface, hybrid Tamm-SPP modes may be excited when a grating on the air-metal interface is introduced. Out-coupling via the grating to free space propagation is shown to enhance the transmission as well as the directionality and polarization selection for the transmitted beam. We suggest that this system will be useful on those devices, where a metallic electrical contact as well as beaming and polarization control is needed

D-branes in Generalized Geometry and Dirac-Born-Infeld Action

The purpose of this paper is to formulate the Dirac-Born-Infeld (DBI) action in a framework of generalized geometry and clarify its symmetry. A D-brane is defined as a Dirac structure where scalar fields and gauge field are treated on an equal footing in a static gauge. We derive generalized Lie derivatives corresponding to the diffeomorphism and B-field gauge transformations and show that the DBI action is invariant under non-linearly realized symmetries for all types of diffeomorphisms and B-field gauge transformations. Consequently, we can interpret not only the scalar field but also the gauge field on the D-brane as the generalized Nambu-Goldstone boson.Comment: 32 pages, 4 figures, ver2:typos corrected, references adde

Time-Dependent Warping, Fluxes, and NCYM

We describe the supergravity solutions dual to D6-branes with both time-dependent and time-independent B-fields. These backgrounds generalize the Taub-NUT metric in two key ways: they have asymmetric warp factors and background fluxes. In the time-dependent case, the warping takes a novel form. Kaluza-Klein reduction in these backgrounds is unusual, and we explore some of the new features. In particular, we describe how a localized gauge-field emerges with an analogue of the open string metric and coupling. We also describe a gravitational analogue of the Seiberg-Witten map. This provides a framework in supergravity both for studying non-commutative gauge theories, and for constructing novel warped backgrounds.Comment: 32 pages, LaTeX, references adde

Crossover between liquid-like and gas-like behaviour in CH4 at 400 K

We report experimental evidence for a crossover between a liquid-like state and a gas-like state in fluid methane (CH4). This crossover is observed in all of our experiments, up to 397 K temperature; 2.1 times the critical temperature of methane. The crossover has been characterized with both Raman spectroscopy and X-ray diffraction in a number of separate experiments, and confirmed to be reversible. We associate this crossover with the Frenkel line - a recently hypothesized crossover in dynamic properties of fluids extending to arbitrarily high pressure and temperature, dividing the phase diagram into separate regions where the fluid possesses liquid-like and gas-like properties. On the liquid-like side the Raman-active vibration increases in frequency linearly as pressure is increased, as expected due to the repulsive interaction between adjacent molecules. On the gas-like side this competes with the attractive Van der Waal’s potential leading the vibration frequency to decrease as pressure is increased

The Pioneer anomaly in the context of the braneworld scenario

We examine the Pioneer anomaly - a reported anomalous acceleration affecting the Pioneer 10/11, Galileo and Ulysses spacecrafts - in the context of a braneworld scenario. We show that effects due to the radion field cannot account for the anomaly, but that a scalar field with an appropriate potential is able to explain the phenomena. Implications and features of our solution are analyzed.Comment: Final version to appear at Classical & Quantum Gravity. Plainlatex 19 page

Optical properties of nanowires based on a blend of poly (9,9-dioctylfluorene) [PFO] and poly(9,9-dioctyl fluorene-alt-benzothiadiazole) [F8BT]

Near-field and far-field optical microscopy are used to study the optical properties of nanowires based on a blend of 95% poly (9,9-dioctylfluorene) [PFO] doped with 5% poly (9,9-dioctylfluorene-alt-benzothiadiazole) [F8BT]. Single nanowires were imaged and optical investigations revealed that they act as nanoscale optical waveguides. Investigation using polarization-resolved far-field PL spectroscopy revealed emission from the nanowires was strongly anisotropic having preferred axial polarization. This suggests that a significant number of the polymer chains are oriented along the nanowire axis