1,870 research outputs found
Optimal policy and Taylor rule cross-checking under parameter uncertainty : [Version 26 September 2013]
We examine whether the robustifying nature of Taylor rule cross-checking under model uncertainty carries over to the case of parameter uncertainty. Adjusting monetary policy based on this kind of cross-checking can improve the outcome for the monetary authority. This, however, crucially depends on the relative welfare weight that is attached to the output gap and also the degree of monetary policy commitment. We find that Taylor rule cross-checking is on average able to improve losses when the monetary authority only moderately cares about output stabilization and when policy is set in a discretionary way
An upper bound from helioseismology on the stochastic background of gravitational waves
The universe is expected to be permeated by a stochastic background of
gravitational radiation of astrophysical and cosmological origin. This
background is capable of exciting oscillations in solar-like stars. Here we
show that solar-like oscillators can be employed as giant hydrodynamical
detectors for such a background in the muHz to mHz frequency range, which has
remained essentially unexplored until today. We demonstrate this approach by
using high-precision radial velocity data for the Sun to constrain the
normalized energy density of the stochastic gravitational-wave background
around 0.11 mHz. These results open up the possibility for asteroseismic
missions like CoRoT and Kepler to probe fundamental physics.Comment: 6 pages, 2 figures. Updated to match published versio
Phase Diagram of Bosons in Two-Color Superlattices from Experimental Parameters
We study the zero-temperature phase diagram of a gas of bosonic 87-Rb atoms
in two-color superlattice potentials starting directly from the experimental
parameters, such as wavelengths and intensities of the two lasers generating
the superlattice. In a first step, we map the experimental setup to a
Bose-Hubbard Hamiltonian with site-dependent parameters through explicit
band-structure calculations. In the second step, we solve the many-body problem
using the density-matrix renormalization group (DMRG) approach and compute
observables such as energy gap, condensate fraction, maximum number
fluctuations and visibility of interference fringes. We study the phase diagram
as function of the laser intensities s_2 and s_1 as control parameters and show
that all relevant quantum phases, i.e. superfluid, Mott-insulator, and quasi
Bose-glass phase, and the transitions between them can be investigated through
a variation of these intensities alone.Comment: 4 pages, 3 figure
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