266 research outputs found
Using privileged information to manipulate markets: insiders, gurus, and credibility
Access to private information is shown to generate both the incentives and the ability to manipulate asset markets through strategically distorted announcements. The fact that privileged information is noisy interferes with the public's attempts to learn whether such announcements are honest; it allows opportunistic individuals to manipulate prices repeatedly, without ever being fully found out. This leads us to extend Sobel's [1985] model of strategic communication to the case of noisy private signals. Our results show that when truthfulness is not easily verifiable, restrictions on trading by insiders may be needed to preserve the integrity of information embodied in prices
On the redistributive power of pensions
We study the tradeoff between efficiency and redistribution in a model with overlapping generations, extensive labor supply, and perfect financial markets. The government instruments are a pension scheme and a age-independent nonlinear income tax schedule. At the second-best optimum, the pension system constrains the agents’ labor supply behavior, forcing them to work to achieve a required lifetime performance. Income taxes affect labor supply directly, but also indirectly through pension incentives. The indirect effect of taxes counteracts the usual forces in the efficiency-redistribution tradeoff: through the interplay with the pension system, decreasing taxes induces redistribution and reduces productive efficiency
Fast-Neutron Activation of Long-Lived Isotopes in Enriched Ge
We measured the production of \nuc{57}{Co}, \nuc{54}{Mn}, \nuc{68}{Ge},
\nuc{65}{Zn}, and \nuc{60}{Co} in a sample of Ge enriched in isotope 76 due to
high-energy neutron interactions. These isotopes, especially \nuc{68}{Ge}, are
critical in understanding background in Ge detectors used for double-beta decay
experiments. They are produced by cosmogenic-neutron interactions in the
detectors while they reside on the Earth's surface. These production rates were
measured at neutron energies of a few hundred MeV. We compared the measured
production to that predicted by cross-section calculations based on CEM03.02.
The cross section calculations over-predict our measurements by approximately a
factor of three depending on isotope. We then use the measured cosmic-ray
neutron flux, our measurements, and the CEM03.02 cross sections to predict the
cosmogenic production rate of these isotopes. The uncertainty in extrapolating
the cross section model to higher energies dominates the total uncertainty in
the cosmogenic production rate.Comment: Revised after feedback and further work on extrapolating cross
sections to higher energies in order to estimate cosmic production rates.
Also a numerical error was found and fixed in the estimate of the Co-57
production rat
Determination of the Cosmic Distance Scale from Sunyaev-Zel'dovich Effect and Chandra X-ray Measurements of High Redshift Galaxy Clusters
We determine the distance to 38 clusters of galaxies in the redshift range
0.14 < z < 0.89 using X-ray data from Chandra and Sunyaev-Zeldovich Effect data
from the Owens Valley Radio Observatory and the Berkeley-Illinois-Maryland
Association interferometric arrays. The cluster plasma and dark matter
distributions are analyzed using a hydrostatic equilibrium model that accounts
for radial variations in density, temperature and abundance, and the
statistical and systematic errors of this method are quantified. The analysis
is performed via a Markov chain Monte Carlo technique that provides
simultaneous estimation of all model parameters. We measure a Hubble constant
of 76.9 +3.9-3.4 +10.0-8.0 km/s/Mpc (statistical followed by systematic
uncertainty at 68% confidence) for an Omega_M=0.3, Omega_Lambda=0.7 cosmology.
We also analyze the data using an isothermal beta model that does not invoke
the hydrostatic equilibrium assumption, and find H_0=73.7 +4.6-3.8 +9.5-7.6
km/s/Mpc; to avoid effects from cool cores in clusters, we repeated this
analysis excluding the central 100 kpc from the X-ray data, and find H_0=77.6
+4.8-4.3 +10.1-8.2 km/s/Mpc. The consistency between the models illustrates the
relative insensitivity of SZE/X-ray determinations of H_0 to the details of the
cluster model. Our determination of the Hubble parameter in the distant
universe agrees with the recent measurement from the Hubble Space Telescope key
project that probes the nearby universe.Comment: ApJ submitted (revised version
ADMX-Orpheus First Search for 70 eV Dark Photon Dark Matter: Detailed Design, Operations, and Analysis
Dark matter makes up 85% of the matter in the universe and 27% of its energy
density, but we don't know what comprises dark matter. It is possible that dark
matter may be composed of either axions or dark photons, both of which can be
detected using an ultra-sensitive microwave cavity known as a haloscope. The
haloscope employed by ADMX consists of a cylindrical cavity operating at the
TM mode and is sensitive to the QCD axion with masses of few eV.
However, this haloscope design becomes challenging to implement for higher
masses. This is because higher masses require smaller-diameter cavities,
consequently reducing the detection volume which diminishes the detected signal
power. ADMX-Orpheus mitigates this issue by operating a tunable,
dielectrically-loaded cavity at a higher-order mode, allowing the detection
volume to remain large. This paper describes the design, operation, analysis,
and results of the inaugural ADMX-Orpheus dark photon search between 65.5
eV (15.8 GHz) and 69.3 eV (16.8 GHz), as well as future directions
for axion searches and for exploring more parameter space.Comment: 21 pages, 29 figures. To be submitted to Physical Review D. arXiv
admin note: substantial text overlap with arXiv:2112.0454
Search for 70 \mu eV Dark Photon Dark Matter with a Dielectrically-Loaded Multi-Wavelength Microwave Cavity
Microwave cavities have been deployed to search for bosonic dark matter
candidates with masses of a few eV. However, the sensitivity of these
cavity detectors is limited by their volume, and the traditionally-employed
half-wavelength cavities suffer from a significant volume reduction at higher
masses. ADMX-Orpheus mitigates this issue by operating a tunable,
dielectrically-loaded cavity at a higher-order mode, which allows the detection
volume to remain large. The ADMX-Orpheus inaugural run excludes dark photon
dark matter with kinetic mixing angle between 65.5 eV
(15.8 GHz) and 69.3 eV (16.8GHz), marking the highest-frequency tunable
microwave cavity dark matter search to date.Comment: 7 pages, 5 figure, to be submitted to PR
- …