5,076 research outputs found

    The spectral invariant approximation within canopy radiative transfer to support the use of the EPIC/DSCOVR oxygen B-band for monitoring vegetation

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    EPIC (Earth Polychromatic Imaging Camera) is a 10-channel spectroradiometer onboard DSCOVR (Deep Space Climate Observatory) spacecraft. In addition to the near-infrared (NIR, 780 nm) and the 'red' (680 nm) channels, EPIC also has the O2 A-band (764±0.2 nm) and B-band (687.75±0.2 nm). The EPIC Normalized Difference Vegetation Index (NDVI) is defined as the difference between NIR and 'red' channels normalized to their sum. However, the use of the O2 B-band instead of the 'red' channel mitigates the effect of atmosphere on remote sensing of surface reflectance because O2 reduces contribution from the radiation scattered by the atmosphere. Applying the radiative transfer theory and the spectral invariant approximation to EPIC observations, the paper provides supportive arguments for using the O2 band instead of the red channel for monitoring vegetation dynamics. Our results suggest that the use of the O2 B-band enhances the sensitivity of the top-of-atmosphere NDVI to the presence of vegetation.Shared Services Center NASAhttp://www.sciencedirect.com/science/article/pii/S0022407317300195First author draf

    Generalized Parton Distributions, Deeply Virtual Compton Scattering and TMDs

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    Parton distributions in impact parameter space, which are obtained by Fourier transforming GPDs, exhibit a significant deviation from axial symmetry when target and/or quark are transversely polarized. In combination with the final state interactions, this transverse deformation provides a natural mechanism for naive-T odd transverse single-spin asymmetries in semi-inclusive DIS. The deformation of PDFs in impact parameter space can also be related to the transverse force acting on the active quark in polarized DIS at higher twist.Comment: 4 pages, invited talk at CIPANP0

    The fate of the Mach cone in covariant transport theory

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    An intriguing potential signature of hydrodynamic behavior in relativistic A+A reactions at Relativistic Heavy Ion Collider (RHIC) energies is conical flow induced by fast supersonic particles traversing the hot and dense medium. Here I present first results on the evolution of Mach shocks in 2->2 covariant transport theory, in a static uniform medium.Comment: Presentation at CIPANP 2009 (Tenth Conference on the Intersections of Particle and Nuclear Physics), May 26-31, 2009, Torrey Pines, California, US

    Physics Beyond the Standard Model

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    I present a brief overview of some exciting possibilities for physics Beyond the Standard Model. I include short discussions of neutrino physics, the strong CP problem and axions, GUTs, large and warped extra dimensions, Little Higgs models and supersymmetry. The chances appear excellent that in the next few years-- as the LHC era gets underway-- data from a bevy of experiments will point the way to a new paradigm for the laws of physics as we know them.Comment: 6 pages; to appear in the Proceedings of the Tenth Conference on the Intersections of Particle and Nuclear Physics (CIPANP 2009), San Diego, California, 26-31 May, 200

    IceCube: Neutrinos Associated with Cosmic Rays

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    After a brief review of the status of the kilometer-scale neutrino observatory IceCube, we discuss the prospect that such detectors discover the still-enigmatic sources of cosmic rays. After all, this aspiration set the scale of the instrument. While only a smoking gun is missing for the case that the Galactic component of the cosmic-ray spectrum originates in supernova remnants, the origin of the extragalactic component remains as inscrutable as ever. We speculate on the role of the nearby active galaxies Centaurus A and M87.Comment: 9 pages, 6 .pdf figures, from a paper presented at CIPANP 09, Torrey Pines, San Diego, C

    alpha_s From the Lattice and Hadronic Tau Decays

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    Until recently, determinations of alpha_s(M_Z) from hadronic tau decays and the analysis of short-distance-sensitive lattice observables yielded results which, though precise, were not in good agreement. I review new analyses that bring these into good agreement and provide some details on the source of the main changes in the tau decay analysis.Comment: 4 pages, prepared for the proceedings of CIPANP 09, San Diego, USA, March 26-31, 200

    Cosmic Ray Muons Timing in the ATLAS Detector

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    In this talk I discuss the use of calorimeter timing both for detector commissioning and in searches for new physics. In particular I present real and simulated cosmic ray muons data results for the ATLAS Tile Calorimeter system. The analysis shows that several detector errors such as imperfect calibrations can be uncovered. I also demonstrate the use of ATLAS Tile Calorimeters excellent timing resolution in suppressing cosmic ray fake missing transverse energy in searches for supersymmetry.Comment: Proceedings of CIPANP 2009, peer-reviewed by the ATLAS Collaboratio

    Underground muons from the direction of Cygnus X-3

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    The flux of underground muons from the direction of the binary Cygnus X-3 was measured by the Soudan 2 proton decay detector. This time-projection calorimeter is located at a depth of 2200 m (water equivalent) in northern Minnesota at latitude 48 deg N, longitude 92 deg W. An analysis was then performed that compared both the total observed flux and the observed flux per transit with the number of events expected in the absence of a source. This expected number of events was determined by combining the detector acceptance as a function of time with detector acceptance as a function of the local spatial coordinates. These functions were evaluated by use of off-source events. The direction of Cygnus X-3 was defined as a 2 deg half-angle cone, centered on the nominal source coordinates. This definition is consistent with the expected appearance of a point source in the Soudan 2 detector after consideration of track reconstruction errors, multiple scattering in the rock, and possible systematic effects. Details of the analysis and the results are presented

    Charm Input for Determining gamma/phi_3

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    Overconstraining the CKM unitarity triangle with precision measurements of its angles continues to test the validity of the Standard Model. One of these angles, gamma/phi_3, has been measured by studying B+- -> D K+- decays, where D = D0 or D0-bar. I present recent results of hadronic D decays which will improve the sensitivity of gamma/phi_3 measurements.Comment: 4 pages, CIPANP 2009 proceedings; references adde

    Photon+jets measurements at D0

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    In this paper, we present a few measurements done at the D0 experiment at the Fermilab Tevatron Collider. These measurements include the triple differential cross sections of the photon and associated jet production, the photon and heavy flavour (b and c) jet, and finally, study of the event with double parton scattering using photon+3 jets events. Each section below presents a brief description of those measurements and results.Comment: To be published in the proceedings of DPF-2009, Detroit, MI, July 2009, eConf C09072
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