46,905 research outputs found
Supersymmetric lepton flavour violation in a linear collider: the role of charginos
The occurrence of a significant amount of supersymmetric lepton flavour
violation at laboratory energies, through
mixing, has become a realistic possibility in the wake of the super-Kamiokande
atmospheric neutrino result. This effect can be observed in an e+e- linear
collider with the distinct final state tau+mu+ jets+E_T. We show that the pair
production of charginos can make an important contribution to this process and
has to be taken into account in addition to that of sneutrinos or charged
sleptons. Some case studies are presented with CM energies of 500 and 800 GeV
and integrated luminosities of 50, 500 and 1000 fb-1.Comment: 15 pages, latex, including 2 figure
Design and fabrication of a boron reinforced intertank skirt
Analytical and experimental studies were performed to evaluate the structural efficiency of a boron reinforced shell, where the medium of reinforcement consists of hollow aluminum extrusions infiltrated with boron epoxy. Studies were completed for the design of a one-half scale minimum weight shell using boron reinforced stringers and boron reinforced rings. Parametric and iterative studies were completed for the design of minimum weight stringers, rings, shells without rings and shells with rings. Computer studies were completed for the final evaluation of a minimum weight shell using highly buckled minimum gage skin. The detail design is described of a practical minimum weight test shell which demonstrates a weight savings of 30% as compared to an all aluminum longitudinal stiffened shell. Sub-element tests were conducted on representative segments of the compression surface at maximum stress and also on segments of the load transfer joint. A 10 foot long, 77 inch diameter shell was fabricated from the design and delivered for further testing
Deconvolution of Images from BLAST 2005: Insight into the K3-50 and IC 5146 Star-forming Regions
We present an implementation of the iterative flux-conserving Lucy-Richardson (L-R) deconvolution method of image restoration for maps produced by the Balloon-borne Large Aperture Submillimeter Telescope (BLAST). Compared to the direct Fourier transform method of deconvolution, the L-R operation restores images with better-controlled background noise and increases source detectability. Intermediate iterated images are useful for studying extended diffuse structures, while the later iterations truly enhance point sources to near the designed diffraction limit of the telescope. The L-R method of deconvolution is efficient in resolving compact sources in crowded regions while simultaneously conserving their respective flux densities. We have analyzed its performance and convergence extensively through simulations and cross-correlations of the deconvolved images with available high-resolution maps. We present new science results from two BLAST surveys, in the Galactic regions K3-50 and IC 5146, further demonstrating the benefits of performing this deconvolution. We have resolved three clumps within a radius of 4'.5 inside the star-forming molecular cloud containing K3-50. Combining the well-resolved dust emission map with available multi-wavelength data, we have constrained the spectral energy distributions (SEDs) of five clumps to obtain masses (M), bolometric luminosities (L), and dust temperatures (T). The L-M diagram has been used as a diagnostic tool to estimate the evolutionary stages of the clumps. There are close relationships between dust continuum emission and both 21 cm radio continuum and ^(12)CO molecular line emission. The restored extended large-scale structures in the Northern Streamer of IC 5146 have a strong spatial correlation with both SCUBA and high-resolution extinction images. A dust temperature of 12 K has been obtained for the central filament. We report physical properties of ten compact sources, including six associated protostars, by fitting SEDs to multi-wavelength data. All of these compact sources are still quite cold (typical temperature below ~ 16 K) and are above the critical Bonner-Ebert mass. They have associated low-power young stellar objects. Further evidence for starless clumps has also been found in the IC 5146 region
Group theoretic dimension of stationary symmetric \alpha-stable random fields
The growth rate of the partial maximum of a stationary stable process was
first studied in the works of Samorodnitsky (2004a,b), where it was
established, based on the seminal works of Rosi\'nski (1995,2000), that the
growth rate is connected to the ergodic theoretic properties of the flow that
generates the process. The results were generalized to the case of stable
random fields indexed by Z^d in Roy and Samorodnitsky (2008), where properties
of the group of nonsingular transformations generating the stable process were
studied as an attempt to understand the growth rate of the partial maximum
process. This work generalizes this connection between stable random fields and
group theory to the continuous parameter case, that is, to the fields indexed
by R^d.Comment: To appear in Journal of Theoretical Probability. Affiliation of the
authors are update
Time Dependent Effects and Transport Evidence for Phase Separation in La_{0.5}Ca_{0.5}MnO_{3}
The ground state of La_{1-x}Ca_{x}MnO_{3} changes from a ferromagnetic
metallic to an antiferromagnetic charge-ordered state as a function of Ca
concentration at x ~ 0.50. We present evidence from transport measurements on a
sample with x = 0.50 that the two phases can coexist, in agreement with other
observations of phase separation in these materials. We also observe that, by
applying and then removing a magnetic field to the mainly charge-ordered state
at some temperatures, we can "magnetically anneal" the charge order, resulting
in a higher zero-field resistivity. We also observe logarithmic time dependence
in both resistivity and magnetization after a field sweep at low temperatures.Comment: 9 pages, LATEX, 3 postscript figure
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