1,814 research outputs found

    Model Independent Electromagnetic corrections in hadronic Ï„\tau decays

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    The long distance correction to the total decay width of the τ±→K0π±ν\tau^{\pm}\to K^{0}\pi^{\pm}\nu decay is calculated in a model independent approach where a discrimination of photons in the Bremmstrahlung process is assumed. This correction is completely free of UV and IR singularities and moreover, it satisfies electromagnetic gauge invariance. The result of this work can be applied on the tau decays: τ±→π±π0ν,K±π0ν\tau^{\pm}\to \pi^{\pm}\pi^{0}\nu, K^{\pm}\pi^{0}\nu

    PAMELA's cosmic positron from decaying LSP in SO(10) SUSY GUT

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    We propose two viable scenarios explaining the recent observations on cosmic positron excess. In both scenarios, the present relic density in the Universe is assumed to be still supported by thermally produced WIMP or LSP (\chi). One of the scenarios is based on two dark matter (DM) components (\chi,X) scenario, and the other is on SO(10) SUSY GUT. In the two DM components scenario, extremely small amount of non-thermally produced meta-stable DM component [O(10^{-10}) < n_X /n_\chi] explains the cosmic positron excess. In the SO(10) model, extremely small R-parity violation for LSP decay to e^\pm is naturally achieved with a non-zero VEV of the superpartner of one right-handed neutrino (\tilde{\nu}^c) and a global symmetry.Comment: 6 pages, Talks presented in PASCOS, SUSY, and COSMO/CosPA in 201

    The Brightest Cluster Galaxy in Abell 85: The Largest Core Known so far

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    We have found that the brightest cluster galaxy (BCG) in Abell~85, Holm 15A, displays the largest core so far known. Its cusp radius, rγ=4.57±0.06r_{\gamma} = 4.57 \pm 0.06 kpc (4.26′′±0.06′′4.26^{\prime\prime}\pm 0.06^{\prime\prime}), is more than 18 times larger than the mean for BCGs, and ≥1\geq1 kpc larger than A2261-BCG, hitherto the largest-cored BCG (Postman, Lauer, Donahue, et al. 2012) Holm 15A hosts the luminous amorphous radio source 0039-095B and has the optical signature of a LINER. Scaling laws indicate that this core could host a supermassive black hole (SMBH) of mass M∙∼(109−1011) M⊙M_{\bullet}\thicksim (10^{9}-10^{11})\,M_{\odot}. We suggest that cores this large represent a relatively short phase in the evolution of BCGs, whereas the masses of their associated SBMH might be set by initial conditions.Comment: 14 pages, 3 figure, 2 tables, accepted for publication in ApJ Letters on October 6th, 2014, replacement of previous manuscript submitted on May 30th, 2014 to astro-p

    Gas Slug Microfluidics: A Unique Tool for Ultrafast, Highly Controlled Growth of Iron Oxide Nanostructures

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    The use of nanomaterials in real life applications is often hampered by our inability to produce them in large quantities while preserving their desired properties in terms of size, shape, and crystalline phase. Here we present a novel continuous method to synthesize nanostructures with an unprecedented degree of control regarding their properties. In particular, the excellent properties of microreactors for chemical synthesis are enhanced by the introduction of gas slugs of tailored composition. Slug dynamics accelerate mixing, reduce processing times (from hours in batch processes to minutes or even seconds), and, depending on the gas atmosphere used, allows one to accurately control the crystalline phase and shape of the resulting nanostructures. Inert (N2), oxidizing (O2), or reducing (CO, H2) gases were used, leading to different morphologies and crystalline structures in a high yield, highly reproducible fabrication process
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