195 research outputs found
SIMP Spectroscopy
We study the interactions between strongly interacting massive particle dark
matter and the Standard Model via a massive vector boson that is kinetically
mixed with the hypercharge gauge boson. The relic abundance is set by 3-to-2
self-interactions of the dark matter, while the interactions with the vector
mediator enable kinetic equilibrium between the dark and visible sectors. We
show that a wide range of parameters is phenomenologically viable and can be
probed in various ways. Astrophysical and cosmological constraints are evaded
due to the p-wave nature of dark matter annihilation into visible particles,
while direct detection methods using electron recoils can be sensitive to parts
of the parameter space. In addition, we propose performing spectroscopy of the
strongly coupled dark sector at e+e- colliders, where the energy of a
mono-photon can track the resonance structure of the dark sector.
Alternatively, some resonances may decay back into Standard Model leptons or
jets, realizing `hidden valley' phenomenology at the LHC and ILC in a concrete
fashion.Comment: 35 pages, 8 figures; v2: matches published version; v3: fixed typos
in Eqs. (4.15), (6.7) and (6.9), results unchange
Method for extracting long-equivalent wavelength interferometric information
A process for extracting long-equivalent wavelength interferometric information from a two-wavelength polychromatic or achromatic interferometer. The process comprises the steps of simultaneously recording a non-linear sum of two different frequency visible light interferograms on a high resolution film and then placing the developed film in an optical train for Fourier transformation, low pass spatial filtering and inverse transformation of the film image to produce low spatial frequency fringes corresponding to a long-equivalent wavelength interferogram. The recorded non-linear sum irradiance derived from the two-wavelength interferometer is obtained by controlling the exposure so that the average interferogram irradiance is set at either the noise level threshold or the saturation level threshold of the film
Wavelength independent interferometer
A polychromatic interferometer utilizing a plurality of parabolic reflective surfaces to properly preserve the fidelity of light wavefronts irrespective of their wavelengths as they pass through the instrument is disclosed. A preferred embodiment of the invention utilizes an optical train which comprises three off-axis parabolas arranged in conjunction with a beam-splitter and a reference mirror to form a Twyman-Green interferometer. An illumination subsystem is provided and comprises a pair of lasers at different preselected wavelengths in the visible spectrum. The output light of the two lasers is coaxially combined by means of a plurality of reflectors and a grating beam combiner to form a single light source at the focal point of the first parabolic reflection surface which acts as a beam collimator for the rest of the optical train. By using visible light having two distinct wavelengths, the present invention provides a long equivalent wavelength interferogram which operates at visible light wherein the effective wavelength is equal to the product of the wavelengths of the two laser sources divided by their difference in wavelength. As a result, the invention provides the advantages of what amounts to long wavelength interferometry but without incurring the disadvantage of the negligible reflection coefficient of the human eye to long wavelength frequencies which would otherwise defeat any attempt to form an interferogram at that low frequency using only one light source
Lightweight, low-cost solar energy collector
A lightweight solar concentrator of the reflecting parabolic or trough type is realized via a thin reflecting film, an inflatable structural housing and tensioned fibers. The reflector element itself is a thin, flexible, specularly-reflecting sheet or film. The film is maintained in the parabolic trough shape by means of a plurality of identical tensioned fibers arranged to be parallel to the longitudinal axis of the parabola. Fiber ends are terminated in two identical spaced anchorplates, each containing a plurality of holes which lie on the desired parabolic contour. In a preferred embodiment, these fibers are arrayed in pairs with one fiber contacting the front side of the reflecting film and the other contacting the back side of the reflecting film. The reflective surface is thereby slidably captured between arrays of fibers which control the shape and position of the reflective film. Gas pressure in the inflatable housing generates fiber tension to achieve a truer parabolic shape
Method and apparatus for white-light dispersed-fringe interferometric measurement of corneal topography
An novel interferometric apparatus and method for measuring the topography of aspheric surfaces, without requiring any form of scanning or phase shifting. The apparatus and method of the present invention utilize a white-light interferometer, such as a white-light Twyman-Green interferometer, combined with a means for dispersing a polychromatic interference pattern, using a fiber-optic bundle and a disperser such as a prism for determining the monochromatic spectral intensities of the polychromatic interference pattern which intensities uniquely define the optical path differences or OPD between the surface under test and a reference surface such as a reference sphere. Consequently, the present invention comprises a snapshot approach to measuring aspheric surface topographies such as the human cornea, thereby obviating vibration sensitive scanning which would otherwise reduce the accuracy of the measurement. The invention utilizes a polychromatic interference pattern in the pupil image plane, which is dispersed on a point-wise basis, by using a special area-to-line fiber-optic manifold, onto a CCD or other type detector comprising a plurality of columns of pixels. Each such column is dedicated to a single point of the fringe pattern for enabling determination of the spectral content of the pattern. The auto-correlation of the dispersed spectrum of the fringe pattern is uniquely characteristic of a particular optical path difference between the surface under test and a reference surface
Analysis of the Tuning Sensitivity of Silicon-on-Insulator Optical Ring Resonators
High-quality-factor optical ring resonators have recently been fabricated in thin silicon-on-insulator (SOI). Practical applications of such devices will require careful tuning of the precise location of the resonance peaks. In particular, one often wants to maximize the resonance shift due to the presence of an active component and minimize the resonance shift due to temperature changes. This paper presents a semianalytic formalism that allows the prediction of such resonance shifts from the waveguide geometry. This paper also presents the results of experiments that show the tuning behavior of several ring resonators and find that the proposed semianalytic formalism agrees with the observed behavior
Vector SIMP dark matter
Strongly Interacting Massive Particles (SIMPs) have recently been proposed as
light thermal dark matter relics. Here we consider an explicit realization of
the SIMP mechanism in the form of vector SIMPs arising from an hidden
gauge theory, where the accidental custodial symmetry protects the stability of
the dark matter. We propose several ways of equilibrating the dark and visible
sectors in this setup. In particular, we show that a light dark Higgs portal
can maintain thermal equilibrium between the two sectors, as can a massive dark
vector portal with its generalized Chern-Simons couplings to the vector SIMPs,
all while remaining consistent with experimental constraints.Comment: 27 pages, 5 figures, Published versio
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