3,658 research outputs found
Halo-independent tests of dark matter annual modulation signals
I derive new halo-independent lower bounds on the product of the dark
matter-nucleon scattering cross section and the local dark matter density that
are valid for annual modulations of dark matter direct detection signals. They
are obtained by making use of halo-independent bounds based on an expansion of
the rate on the Earth's velocity that were derived in previous works. In
combination with astrophysical measurements of the local energy density, an
observed annual modulation implies a lower bound on the cross section that is
independent of the velocity distribution and that must be fulfilled by any
particle physics model. In order to illustrate the power of the bounds we apply
them to DAMA/LIBRA data and obtain quite strong results when compared to the
standard halo model predictions. We also extend the bounds to the case of
multi-target detectors.Comment: 23 pages, 5 figures, 1 table. Extended discussion on the phase, one
figure added, minor changes, results unchanged. Matches published version in
JCA
Productivity comparisons: the european union agriculture
This paper ail11s at l11easuring the total factor productivity (TFP) of the European agricultural finns. With a Translog index, an interspatial comparison of tIle twelve European countries and intertel11poral productivity variations are computed to l11easure the different rate of TFP
(Translog, Fisher and Hulten indexes) in the European firms. The approach that we use is to calculate non parametric indexex of total factor productivity which allow flexible l110delling of underlying technology and easy calculation from the account data of the firms. The implication
of the quasi-fix family work factor for the short mn and long mn equilibrium of the firms differ between countries and has consequences on the TFP path. The final cornments offer some explanation according with theory available
A halo-independent lower bound on the dark matter capture rate in the Sun from a direct detection signal
We show that a positive signal in a dark matter (DM) direct detection
experiment can be used to place a lower bound on the DM capture rate in the
Sun, independent of the DM halo. For a given particle physics model and DM mass
we obtain a lower bound on the capture rate independent of the local DM
density, velocity distribution, galactic escape velocity, as well as the
scattering cross section. We illustrate this lower bound on the capture rate by
assuming that upcoming direct detection experiments will soon obtain a
significant signal. When comparing the lower bound on the capture rate with
limits on the high-energy neutrino flux from the Sun from neutrino telescopes,
we can place upper limits on the branching fraction of DM annihilation channels
leading to neutrinos. With current data from IceCube and Super-Kamiokande
non-trivial limits can be obtained for spin-dependent interactions and direct
annihilations into neutrinos. In some cases also annihilations into
or start getting constrained. For spin-independent interactions
current constraints are weak, but they may become interesting for data from
future neutrino telescopes.Comment: 27 pages, 8 figures. Added discussion on equilibrium. Added section
5.4 on form factor uncertainties. Updated figures with SK new limits.
Published in JCA
Astrophysics independent bounds on the annual modulation of dark matter signals
We show how constraints on the time integrated event rate from a given dark
matter (DM) direct detection experiment can be used to set a stringent
constraint on the amplitude of the annual modulation signal in another
experiment. The method requires only very mild assumptions about the properties
of the local DM distribution: that it is temporally stable on the scale of
months and spatially homogeneous on the ecliptic. We apply the method to the
annual modulation signal in DAMA/LIBRA, which we compare to the bounds derived
from the constraints on the time-averaged rates from XENON10, XENON100, CDMS
and SIMPLE. Assuming a DM mass of 10 GeV, we show that a DM interpretation of
the DAMA/LIBRA signal is excluded at 6.3sigma (4.6sigma) for isospin conserving
(violating) spin-independent interactions, and at 4.9sigma for spin-dependent
interactions on protons.Comment: 4 pages, 4 figure
Elimination for generic sparse polynomial systems
We present a new probabilistic symbolic algorithm that, given a variety
defined in an n-dimensional affine space by a generic sparse system with fixed
supports, computes the Zariski closure of its projection to an l-dimensional
coordinate affine space with l < n. The complexity of the algorithm depends
polynomially on combinatorial invariants associated to the supports.Comment: 22 page
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