Gravitational Higgs Mechanism

We discuss the gravitational Higgs mechanism in domain wall background solutions that arise in the theory of 5-dimensional Einstein-Hilbert gravity coupled to a scalar field with a non-trivial potential. The scalar fluctuations in such backgrounds can be completely gauged away, and so can be the graviphoton fluctuations. On the other hand, we show that the graviscalar fluctuations do not have normalizable modes. As to the 4-dimensional graviton fluctuations, in the case where the volume of the transverse dimension is finite the massive modes are plane-wave normalizable, while the zero mode is quadratically normalizable. We then discuss the coupling of domain wall gravity to localized 4-dimensional matter. In particular, we point out that this coupling is consistent only if the matter is conformal. This is different from the Randall-Sundrum case as there is a discontinuity in the delta-function-like limit of such a smooth domain wall - the latter breaks diffeomorphisms only spontaneously, while the Randall-Sundrum brane breaks diffeomorphisms explicitly. Finally, at the quantum level both the domain wall as well as the Randall-Sundrum setups suffer from inconsistencies in the coupling between gravity and localized matter, as well as the fact that gravity is generically expected to be delocalized in such backgrounds due to higher curvature terms.Comment: 16 pages, revtex; a minor correctio

Extracting New Physics from the CMB

We review how initial state effects generically yield an oscillatory component in the primordial power spectrum of inflationary density perturbations. These oscillatory corrections parametrize unknown new physics at a scale $M$ and are potentially observable if the ratio $H_{infl}/M$ is sufficiently large. We clarify to what extent present and future CMB data analysis can distinguish between the different proposals for initial state corrections.Comment: Invited talk by B. Greene at the XXII Texas Symposium on Relativistic Astrophysics, Stanford University, 13-17 December 2004, (TSRA04-0001), 8 pages, LaTeX, some references added, added paragraph at the end of section 2 and an extra note added after the conclusions regarding modifications to the large k power spectra deduced from galaxy survey

Observing the Geometry of Warped Compactification via Cosmic Inflation

Using DBI inflation as an example, we demonstrate that the detailed geometry of warped compactification can leave an imprint on the cosmic microwave background (CMB). We compute CMB observables for DBI inflation in a generic class of warped throats and find that the results (such as the sign of the tilt of the scalar perturbations and its running) depend sensitively on the precise shape of the warp factor. In particular, we analyze the warped deformed conifold and find that the results can differ from those of other warped geometries, even when these geometries approximate well the exact metric of the warped deformed conifold.Comment: 4 pages, 3 figures. v2: References and clarifications adde

Mathematics for Visual Guidance of Robots

Vision can be used to position a robot relative to a known object or a known environment in 3D. If the object has enough feature points, one view is sufficient for determining the relative position between the object and the camera, otherwise, multiple views are required. We discuss the mathematics of viewpoint determination, using a combination of calibration matrix decomposition and space resection. The combined method has low noise sensitivity and does not require knowledge of camera parameters. If the object does not have enough features, multiple views are required to determine its position and orientation; an example of this is be given. The formulation of homogeneous transform equations to drive the manipulator to the goal position is also be given

Similarity between Kaluza-Klein and Open-string amplitudes in Diphoton Production

We calculate the tree-level open-string amplitudes for the scattering of four massless particles with diphoton final states. These amplitudes are required to reproduce those of standard model at the tree level in the low energy limit. After low energy stringy corrections, we found that they have similar form to the same processes induced by exchange of the Kaluza-Klein(KK) excitations of graviton in ADD scenario. Using this similarity, we apply constraints on the KK mass scale $M_D$ to the string scale $M_S$. The results are consistent with constraints from the 4-fermion scattering, about $0.6-0.9$ TeV.Comment: 10 pages, modified reference

Non-Minimal and Non-Universal Supersymmetry

I motivate and discuss non-minimal and non-universal models of supersymmetry and supergravity consistent with string unification at $10^{16}$ GeV.Comment: 10 pages, Latex. Plenary talk given at 6th Workshop in High Energy Physics Phenomenology (WHEPP 6), Chennai (Madras), India, 3-15 Jan 200

"Self-tuning" and Conformality

We consider an infinite-volume brane world setup where a codimension one brane is coupled to bulk gravity plus a scalar field with vanishing potential. The latter is protected by bulk supersymmetry, which is intact even if brane supersymmetry is completely broken as the volume of the extra dimension is infinite. Within this setup we discuss a flat solution with a ``self-tuning'' property, that is, such a solution exists for a continuous range of values for the brane tension. This infinite-volume solution is free of any singularities, and has the property that the brane cosmological constant is protected by bulk supersymmetry. We, however, also point out that consistency of the coupling between bulk gravity and brane matter generically appears to require that the brane world-volume theory be conformal.Comment: 13 pages, revtex; minor misprints and references corrected, clarifying remarks added (to appear in Mod. Phys. Lett. A

Remote Infrared Thermography for In-Flight Flow Diagnostics

The feasibility of remote in-flight boundary layer visualization via infrared in incompressible flow was established in earlier flight experiments. The past year's efforts focused on refining and determining the extent and accuracy of this technique of remote in-flight flow visualization via infrared. Investigations were made into flow separation visualization, visualization at transonic conditions, shock visualization, post-processing to mitigate banding noise in the NITE Hawk's thermograms, and a numeric model to predict surface temperature distributions. Although further flight tests are recommended, this technique continues to be promising

A blog mining framework

Blogs have become increasingly popular, and new blogs are generated every day. Many of the contents are useful for applications in various domains, such as business, politics, research, social work, and linguistics. However, automatically collecting and analyzing blogs isn't straightforward due to the large size and dynamic nature of the blogosphere. In this article, the authors propose a framework for blog mining that includes spiders, parsers, analyzers, and visualizers. They present several examples of blog mining applications based on their framework. © 2006 IEEE.published_or_final_versio

Maximal Temperature in Flux Compactifications

Thermal corrections have an important effect on moduli stabilization leading to the existence of a maximal temperature, beyond which the compact dimensions decompactify. In this note, we discuss generality of our earlier analysis and apply it to the case of flux compactifications. The maximal temperature is again found to be controlled by the supersymmetry breaking scale, T_{crit} \sim \sqrt{m_{3/2} M_P}.Comment: 10 pages, 10 figures. v2:comment and references adde