1,763 research outputs found

    QED Corrections to the Scattering of Solar Neutrinos and Electrons

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    We discuss recent calculations of the O(alpha) QED corrections to the recoil electron energy spectrum in neutrino electron scattering, and to the spectrum of the combined energy of the recoil electron and a possible accompanying photon emitted in the scattering process. We then examine the role of these corrections in the interpretation of precise measurements from solar neutrino electron scattering experiments.Comment: (16 Pages, 4 Figures) Presented at the Symposium in Honor of Professor Alberto Sirlin's 70th Birthday: ``50 Years of Precision Electroweak Physics'', New York University, October 27-28, 200

    Using the Short-Wave Infrared for Nocturnal Detection of Combustion Sources in VIIRS Data

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    Night-time images from the SNPP satellite VIIRS scanning radiometer in visible and infrared spectral bands provide invaluable data for detection and characterization of natural and technological combustion sources on the surface of the Earth, such as forest fires, gas flares, steel mills or active volcanoes. The presence of sub-pixel hot infrared (IR) emission sources can be readily detected at night in 1.6 micron near-infrared M10 channel. Their temperature and radiant heat intensity can be estimated by fitting of the Planck black-body spectral curve to the observed radiances of VIIRS infrared M-channels out to 4 um. VIIRS instrument is sensitive to the IR sources over a wide range of temperatures. This method can discriminate low temperature sources such as volcanoes and forest fires from the high temperature gas flares with 300 m average location error. The processing includes correction for panoramic “bow-tie” effect and filtering of the false detections resulting from sensor bombardment by the cosmic rays, especially at the aurora rings and at the South Atlantic anomaly. False detections can be largely removed by correlating of the observed bright spots in M10 channel with other infrared and the visible day-night band. NGDC NOAA provides global daily detection products for thousands of IR sources as KMZ vector maps and as CSV tables

    Why VIIRS data are superior to DMSP for mapping nighttime lights

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    For more than forty years the U.S. Air Force Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) has been the only satellite system collecting global low-light imaging data.  A series of twenty-four DMSP satellites have collected low-light imaging data.  The design of the OLS has not changed significantly since satellite F-4 flew in the late 1970’s and OLS data have relatively coarse spatial resolution, limited dynamic range, and lack in-flight calibration.  In 2011 NASA and NOAA launched the Suomi National Polar Partnership (SNPP) satellite carrying the first Visible Infrared Imaging Radiometer Suite (VIIRS)  instrument.  The VIIRS collects low light imaging data and has several improvements  over the OLS’ capabilities.  In this paper we contrast the nighttime low light imaging collection capabilities of these two systems and compare their data products

    QED Corrections to Neutrino Electron Scattering

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    We evaluate the O(alpha) QED corrections to the recoil electron energy spectrum in the process nu_l + e --> nu_l + e (+gamma), where (+gamma) indicates the possible emission of a photon and l=e, mu or tau. The soft and hard bremsstrahlung differential cross sections are computed for an arbitrary value of the photon energy threshold. We also study the O(alpha) QED corrections to the differential cross section with respect to the total combined energy of the recoil electron and a possible accompanying photon. Their difference from the corrections to the electron spectrum is investigated. We discuss the relevance and applicability of both radiative corrections, emphasizing their role in the analysis of precise solar neutrino electron scattering experiments.Comment: 14 pages + 10 figures. Minimal changes, published versio

    Search for low-mass dilepton resonances in Higgs boson decays to four-lepton final states in proton–proton collisions at √s=13TeV

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    A search for low-mass dilepton resonances in Higgs boson decays is conducted in the four-lepton final state. The decay is assumed to proceed via a pair of beyond the standard model particles, or one such particle and a Z boson. The search uses proton–proton collision data collected with the CMS detector at the CERN LHC, corresponding to an integrated luminosity of 137 fb−1, at a center-of-mass energy √s = 13 TeV. No significant deviation from the standard model expectation is observed. Upper limits at 95% confidence level are set on model-independent Higgs boson decay branching fractions. Additionally, limits on dark photon and axion-like particle production, based on two specific models, are reported

    Measurements of production cross sections of WZ and same-sign WW boson pairs in association with two jets in proton-proton collisions at √s = 13 TeV

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    The first measurements of production cross sections of polarized same-sign W±^{±} W±^{±} boson pairs in proton-proton collisions are reported. The measurements are based on a data sample collected with the CMS detector at the LHC at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 137fb−1^{-1}. Events are selected by requiring exactly two same-sign leptons, electrons or muons, moderate missing transverse momentum, and two jets with a large rapidity separation and a large dijet mass to enhance the contribution of same-sign W±^{±} W±^{±} scattering events. An observed (expected) 95% confidence level upper limit of 1.17 (0.88) fbis set on the production cross section for longitudinally polarized same-sign W±^{±} W±^{±} boson pairs. The electroweak production of same-sign W±^{±} W±^{±} boson pairs with at least one of the W bosons longitudinally polarized is measured with an observed (expected) significance of 2.3 (3.1) standard deviations

    Inclusive search for highly boosted Higgs bosons decaying to bottom quark-antiquark pairs in proton-proton collisions at <mml:msqrt>s</mml:msqrt>=13 TeV

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    Search for decays of the 125 GeV Higgs boson into a Z boson and a ρ or ϕ meson

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    Decays of the 125 GeV Higgs boson into a Z boson and a ρ^0(770) or ϕ(1020) meson are searched for using proton-proton collision data collected by the CMS experiment at the LHC at √s = 13 TeV. The analysed data set corresponds to an integrated luminosity of 137 fb⁻Âč. Events are selected in which the Z boson decays into a pair of electrons or a pair of muons, and the ρ and ϕ mesons decay into pairs of pions and kaons, respectively. No significant excess above the background model is observed. As different polarization states are possible for the decay products of the Z boson and ρ or ϕ mesons, affecting the signal acceptance, scenarios in which the decays are longitudinally or transversely polarized are considered. Upper limits at the 95% confidence level on the Higgs boson branching fractions into Zρ and Zϕ are determined to be 1.04–1.31% and 0.31–0.40%, respectively, where the ranges reflect the considered polarization scenarios; these values are 740–940 and 730–950 times larger than the respective standard model expectations. These results constitute the first experimental limits on the two decay channels

    Combined searches for the production of supersymmetric top quark partners in proton–proton collisions at √s=13Te

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    A combination of searches for top squark pair production using proton–proton collision data at a center-of-mass energy of 13TeV at the CERN LHC, corresponding to an integrated luminosity of 137fb−1^{-1} collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on the model, the combined result excludes a top squark mass up to 1325GeV for a massless neutralino, and a neutralino mass up to 700GeV for a top squark mass of 1150GeV. Top squarks with masses from 145 to 295GeV, for neutralino masses from 0 to 100GeV, with a mass difference between the top squark and the neutralino in a window of 30GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420GeV
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