3,234 research outputs found
Universal Behavior in Large-scale Aggregation of Independent Noisy Observations
Aggregation of noisy observations involves a difficult tradeoff between
observation quality, which can be increased by increasing the number of
observations, and aggregation quality which decreases if the number of
observations is too large. We clarify this behavior for a protypical system in
which arbitrarily large numbers of observations exceeding the system capacity
can be aggregated using lossy data compression. We show the existence of a
scaling relation between the collective error and the system capacity, and show
that large scale lossy aggregation can outperform lossless aggregation above a
critical level of observation noise. Further, we show that universal results
for scaling and critical value of noise which are independent of system
capacity can be obtained by considering asymptotic behavior when the system
capacity increases toward infinity.Comment: 10 pages, 3 figure
How can we test seesaw experimentally?
The seesaw mechanism for the small neutrino mass has been a popular paradigm,
yet it has been believed that there is no way to test it experimentally. We
present a conceivable outcome from future experiments that would convince us of
the seesaw mechanism. It would involve a variety of data from LHC, ILC,
cosmology, underground, and low-energy flavor violation experiments to
establish the case.Comment: 5 pages, 4 figure
Quark mass uncertainties revive KSVZ axion dark matter
The Kaplan-Manohar ambiguity in light quark masses allows for a larger
uncertainty in the ratio of up to down quark masses than naive estimates from
the chiral Lagrangian would indicate. We show that it allows for a relaxation
of experimental bounds on the QCD axion, specifically KSVZ axions in the eV mass range composing 100% of the galactic dark matter halo can evade the
experimental limits placed by the ADMX collaboration.Comment: 9 pages, 5 figure
Cascade events at IceCube + DeepCore as a definitive constraint on the dark matter interpretation of the PAMELA and Fermi anomalies
Dark matter decaying or annihilating into μ^+μ^- or τ^+τ^- has been proposed as an explanation for the e^± anomalies reported by PAMELA and Fermi. Recent analyses show that IceCube, supplemented by DeepCore, will be able to significantly constrain the parameter space of decays to μ^+μ^-, and rule out decays to τ^+τ^- and annihilations to μ^+μ^- in less than five years of running. These analyses rely on measuring tracklike events in IceCube + DeepCore from down-going ν_μ. In this paper we show that by instead measuring cascade events, which are induced by all neutrino flavors, IceCube + DeepCore can rule out decays to μ^+μ^- in only three years of running, and rule out decays to τ^+τ^- and annihilation to μ^+μ^- in only one year of running. These constraints are highly robust to the choice of dark matter halo profile and independent of dark matter-nucleon crosssection
Stable splittings, spaces of representations and almost commuting elements in Lie groups
In this paper the space of almost commuting elements in a Lie group is
studied through a homotopical point of view. In particular a stable splitting
after one suspension is derived for these spaces and their quotients under
conjugation. A complete description for the stable factors appearing in this
splitting is provided for compact connected Lie groups of rank one.By using
symmetric products, the colimits \Rep(\Z^n, SU), \Rep(\Z^n,U) and
\Rep(\Z^n, Sp) are explicitly described as finite products of
Eilenberg-MacLane spaces.Comment: 37 Pages. To appear in Math. Proc. Camb. Phil. So
Experimental Test of a New Equality: Measuring Heat Dissipation in an Optically Driven Colloidal System
Measurement of energy dissipation in small nonequilibrium systems is
generally a difficult task. Recently, Harada and Sasa [Phys.Rev.Lett. 95,
130602(2005)] derived an equality relating the energy dissipation rate to
experimentally accessible quantities in nonequilibrium steady states described
by the Langevin equation. Here, we show the first experimental test of this new
relation in an optically driven colloidal system. We find that this equality is
validated to a fairly good extent, thus the irreversible work of a small system
is estimated from readily obtainable quantities.Comment: 4 pages, 6 figure
High-Energy Neutrino Signatures of Dark Matter Decaying into Leptons
Decaying dark matter has previously been proposed as a possible explanation
for the excess high energy cosmic ray electrons and positrons seen by PAMELA
and the Fermi Gamma-Ray Space Telescope (FGST). To accommodate these signals
however, the decays must be predominantly leptonic, to muons or taus, and
therefore produce neutrinos, potentially detectable with the IceCube neutrino
observatory. We find that, with five years of data, IceCube (supplemented by
DeepCore) will be able to significantly constrain the relevant parameter space
of decaying dark matter, and may even be capable of discovering dark matter
decaying in the halo of the Milky Way.Comment: 4 pages, 1 figur
111In Implantation in Iron and PAC Spectroscopy
開始ページ、終了ページ: 冊子体のページ付
Discriminating spin through quantum interference
Many of the proposed solutions to the hierarchy and naturalness problems
postulate new `partner' fields to the standard model particles. Determining the
spins of these new particles will be critical in distinguishing among the
various possible SM extensions, yet proposed methods rely on the underlying
models. We propose a new model-independent method for spin measurements which
takes advantage of quantum interference among helicity states. We demonstrate
that this method will be able to discriminate scalar particles from higher spin
states at the ILC, and discuss application to higher spins and possible uses at
the LHC.Comment: 11 pages, 11 figure
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