4,652 research outputs found

    Symmetries of the near horizon of a Black Hole by Group Theoretic methods

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    We use group theoretic methods to obtain the extended Lie point symmetries of the quantum dynamics of a scalar particle probing the near horizon structure of a black hole. Symmetries of the classical equations of motion for a charged particle in the field of an inverse square potential and a monopole, in the presence of certain model magnetic fields and potentials are also studied. Our analysis gives the generators and Lie algebras generating the inherent symmetries.Comment: To appear in Int. J. Mod. Phys.

    The ISOPHOT-MAMBO survey of 3CR radio sources: Further evidence for the unified schemes

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    We present the complete set of ISOPHOT observations of 3CR radio galaxies and quasars, which are contained in the ISO Data Archive, providing 75 mid- and far-infrared spectral energy distributions (SEDs) between 5 and 200 micron. For 28 sources they are supplemented with MAMBO 1.2 mm observations and for 15 sources with new submillimetre data from the SCUBA archive. We check the orientation-dependent unified scheme, in which the powerful FR2 narrow line galaxies are quasars viewed at high inclination, so that their nuclei are hidden behind a dust torus intercepting the optical-ultraviolet AGN radiation and reemitting it in the infrared. We find that (1) both the quasars and the galaxies show a high mid- to far-infrared luminosity ratio typical for powerful AGNs and (2) -- when matched in 178 MHz luminosity -- both show the same ratio of isotropic far-infrared to isotropic 178 MHz lobe power. Therefore, from our large sample investigated here we find strong evidence for the orientation-dependent unification of the powerful FR2 galaxies with the quasars.Comment: 16 pages, 7 figures, 3 tables, accepted by Astronomy & Astrophysic

    Infrared to millimetre photometry of ultra-luminous IR galaxies: new evidence favouring a 3-stage dust model

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    Infrared to millimetre spectral energy distributions have been obtained for 41 bright ultra-luminous infrared galaxies. The observations were carried out with ISOPHOT between 10 and 200 micron and supplemented for 16 sources with SCUBA at 450 and 850 micron and with SEST at 1.3 mm. In addition, seven sources were observed at 1.2 and 2.2 μ\mum with the 2.2 m telescope on Calar Alto. These new SEDs represent the most complete set of infrared photometric templates obtained so far on ULIRGs in the local universe.Comment: 23 pages, 11 figures, accepted for publication in Astronomy & Astrophysic

    A Letter of Intent to Install a milli-charged Particle Detector at LHC P5

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    In this LOI we propose a dedicated experiment that would detect "milli-charged" particles produced by pp collisions at LHC Point 5. The experiment would be installed during LS2 in the vestigial drainage gallery above UXC and would not interfere with CMS operations. With 300 fb1^{-1} of integrated luminosity, sensitivity to a particle with charge O(103) e\mathcal{O}(10^{-3})~e can be achieved for masses of O(1)\mathcal{O}(1) GeV, and charge O(102) e\mathcal{O}(10^{-2})~e for masses of O(10)\mathcal{O}(10) GeV, greatly extending the parameter space explored for particles with small charge and masses above 100 MeV.Comment: 19 pages, 7 figure

    Travel Burden to Breast MRI and Utilization: Are Risk and Sociodemographics Related?

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    Mammograms, unlike magnetic resonance imaging (MRI), are relatively geographically accessible. Additional travel time is often required to access breast MRI. However, the amount of additional travel time and whether it varies based on sociodemographic or breast cancer risk factors is unknown

    Oscillations above the barrier in the fusion of 28Si + 28Si

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    Fusion cross sections of 28Si + 28Si have been measured in a range above the barrier with a very small energy step (DeltaElab = 0.5 MeV). Regular oscillations have been observed, best evidenced in the first derivative of the energy-weighted excitation function. For the first time, quite different behaviors (the appearance of oscillations and the trend of sub-barrier cross sections) have been reproduced within the same theoretical frame, i.e., the coupled-channel model using the shallow M3Y+repulsion potential. The calculations suggest that channel couplings play an important role in the appearance of the oscillations, and that the simple relation between a peak in the derivative of the energy-weighted cross section and the height of a centrifugal barrier is lost, and so is the interpretation of the second derivative of the excitation function as a barrier distribution for this system, at energies above the Coulomb barrier.Comment: submitted to Physics Letters

    Letter of Intent: Search for sub-millicharged particles at J-PARC

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    We propose a new experiment sensitive to the detection of millicharged particles produced at the 3030 GeV proton fixed-target collisions at J-PARC. The potential site for the experiment is B2 of the Neutrino Monitor building, 280280 m away from the target. With NPOT=1022\textrm{N}_\textrm{POT}=10^{22}, the experiment can provide sensitivity to particles with electric charge 3×104e3\times10^{-4}\,e for mass less than 0.20.2 GeV/c2\textrm{GeV}/\textrm{c}^2 and 1.5×103e1.5\times10^{-3}\,e for mass less than 1.61.6 GeV/c2\textrm{GeV}/\textrm{c}^2. This brings a substantial extension to the current constraints on the charge and the mass of such particles
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