89,362 research outputs found
Micro-fabricated electromagnetic filters for millikelvin experiments
In this article we report on the design, fabrication and tests of
micro-fabricated broadband filters suitable for proper electromagnetic
thermalization of electrical lines connected to sensitive quantum electronics
experiments performed at dilution fridge temperatures. Compared to previous
such miniature filters, the new design improves on performance and reliability.
These filters can be packed in space-saving cases with either single or
multi-contact connectors. Measured performance in the accessible range compares
well to simulations. We use these simulations to discuss the effectiveness of
these filters for electromagnetic thermalization at 30 mK.Comment: Available at http://www-spht.cea.fr/articles/s06/03
Inattentive professional forecasters
We use the ECB Survey of Professional Forecasters to characterize the dynamics of expectations at the micro level. We find that forecasters (i) have predictable forecast errors; (ii) disagree; (iii) fail to systematically update their forecasts in the wake of new information; (iv) disagree even when updating; and (v) differ in their frequency of updating and forecast performances. We argue that these micro data facts are qualitatively in line with recent models in which expectations are formed by inattentive agents. However building and estimating an expectation model that features two types of inattention, namely sticky information à la Mankiw-Reis and noisy information à la Sims, we cannot quantitatively generate the error and disagreement that are observed in the SPF data. The rejection is mainly due to the fact that professionals relatively agree on very sluggish forecasts.imperfect information, inattention, forecast errors, disagreement, business cycle.
Progress on testing Lorentz symmetry with MICROSCOPE
The Weak Equivalence Principle (WEP) and the local Lorentz invariance (LLI)
are two major assumptions of General Relativity (GR). The MICROSCOPE mission,
currently operating, will perform a test of the WEP with a precision of
. The data will also be analysed at SYRTE for the purposes of a LLI
test realised in collaboration with J. Tasson (Carleton College, Minnesota) and
Q. Bailey (Embry-Riddle Aeronautical University, Arizona). This study will be
performed in a general framework, called the Standard Model Extension (SME),
describing Lorentz violations that could appear at Planck scale (
GeV). The SME allows us to derive a Lorentz violating observable designed for
the MICROSCOPE experiment and to search for possible deviations from LLI in the
differential acceleration of the test masses
Phase controlled superconducting proximity effect probed by tunneling spectroscopy
Using a dual-mode STM-AFM microscope operating below 50mK we measured the
Local Density of States (LDoS) along small normal wires connected at both ends
to superconductors with different phases. We observe that a uniform minigap can
develop in the whole normal wire and in the superconductors near the
interfaces. The minigap depends periodically on the phase difference. The
quasiclassical theory of superconductivity applied to a simplified 1D model
geometry accounts well for the data.Comment: Accepted for publication in Physical Review Letter
Probing New Physics using top quark polarization in the e+e- -> t \bar{t} process at future Linear Colliders
We investigate the sensitivity to new physics of the process e+e- -> t bar{t}
when the top polarization is analyzed using leptonic final states e+e- -> t
\bar{t} -> l+l- b \bar{b} nu_l \bar{nu}_l. We first show that the kinematical
reconstruction of the complete kinematics is experimentally tractable for this
process. Then we apply the matrix element method to study the sensitivity to
the Vt\bar{t} coupling (V being a vector gauge boson), at the tree level and in
the narrow width approximation. Assuming the ILC baseline configuration,
sqrt{S}=500 GeV, and a luminosity of 500 fb^{-1}, we conclude that this optimal
analysis allows to determine simultaneously the ten form factors that
parameterize the Vt\bar{t} coupling, below the percent level. We also discuss
the effects of the next leading order (NLO) electroweak corrections using the
GRACE program with polarized beams. It is found that the NLO corrections to
different beam polarization lead to significantly different patterns of
contributions.Comment: 14 pages, 4 figures, Proceedings for the TYL-FJPPL workshops on "Top
Physics at ILC
Shock statistics in higher-dimensional Burgers turbulence
We conjecture the exact shock statistics in the inviscid decaying Burgers
equation in D>1 dimensions, with a special class of correlated initial
velocities, which reduce to Brownian for D=1. The prediction is based on a
field-theory argument, and receives support from our numerical calculations. We
find that, along any given direction, shocks sizes and locations are
uncorrelated.Comment: 4 pages, 8 figure
Breakup of diminutive Rayleigh jets
Discharging a liquid from a nozzle at sufficient large velocity leads to a
continuous jet that due to capillary forces breaks up into droplets. Here we
investigate the formation of microdroplets from the breakup of micron-sized
jets with ultra high-speed imaging. The diminutive size of the jet implies a
fast breakup time scale of the
order of 100\,ns{}, and requires imaging at 14 million frames per second. We
directly compare these experiments with a numerical lubrication approximation
model that incorporates inertia, surface tension, and viscosity [Eggers and
Dupont, J. Fluid Mech. 262, 205 (1994); Shi, Brenner, and Nagel, Science 265,
219 (1994)]. The lubrication model allows to efficiently explore the parameter
space to investigate the effect of jet velocity and liquid viscosity on the
formation of satellite droplets. In the phase diagram we identify regions where
the formation of satellite droplets is suppressed. We compare the shape of the
droplet at pinch-off between the lubrication approximation model and a boundary
integral (BI) calculation, showing deviations at the final moment of the
pinch-off. Inspite of this discrepancy, the results on pinch-off times and
droplet and satellite droplet velocity obtained from the lubrication
approximation agree with the high-speed imaging results
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