3,839 research outputs found

    Universal Behavior in Large-scale Aggregation of Independent Noisy Observations

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    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

    Field Quantization in 5D Space-Time with Z2_2-parity and Position/Momentum Propagator

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    Field quantization in 5D flat and warped space-times with Z2_2-parity is comparatively examined. We carefully and closely derive 5D position/momentum(P/M) propagators. Their characteristic behaviours depend on the 4D (real world) momentum in relation to the boundary parameter (ll) and the bulk curvature (\om). They also depend on whether the 4D momentum is space-like or time-like. Their behaviours are graphically presented and the Z2_2 symmetry, the "brane" formation and the singularities are examined. It is shown that the use of absolute functions is important for properly treating the singular behaviour. The extra coordinate appears as a {\it directed} one like the temperature. The δ(0)\delta(0) problem, which is an important consistency check of the bulk-boundary system, is solved {\it without} the use of KK-expansion. The relation between P/M propagator (a closed expression which takes into account {\it all} KK-modes) and the KK-expansion-series propagator is clarified. In this process of comparison, two views on the extra space naturally come up: orbifold picture and interval (boundary) picture. Sturm-Liouville expansion (a generalized Fourier expansion) is essential there. Both 5D flat and warped quantum systems are formulated by the Dirac's bra and ket vector formalism, which shows the warped model can be regarded as a {\it deformation} of the flat one with the {\it deformation parameter} \om. We examine the meaning of the position-dependent cut-off proposed by Randall-Schwartz.Comment: 44 figures, 22(fig.)+41 pages, to be published in Phys.Rev.D, Fig.4 is improve

    Quark mass uncertainties revive KSVZ axion dark matter

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    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 23μ2-3 \mueV 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

    More Visible Effects of the Hidden Sector

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    There is a growing appreciation that hidden sector dynamics may affect the supersymmetry breaking parameters in the visible sector (supersymmetric standard model), especially when the dynamics is strong and superconformal. We point out that there are effects that have not been previously discussed in the literature. For example, the gaugino masses are suppressed relative to the gravitino mass. We discuss their implications in the context of various mediation mechanisms. The issues discussed include anomaly mediation with singlets, the mu (B mu) problem in gauge and gaugino mediation, and distinct mass spectra for the superparticles that have not been previously considered.Comment: 25 pages; small clarifications and corrections, version to appear in Phys. Rev.

    High-Energy Neutrino Signatures of Dark Matter Decaying into Leptons

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    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
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