Browsing Physics & Astronomy by Issue Date

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  • Das, Saurya; Dasgupta, Arundhati; Ramadevi, P.; Sarkar, Tapobrata (Elsevier BV North HollandInstitute of Mathematical Sciences (India)International Centre for Theoretical PhysicsTata Institute of Fundamental Research, 1988)
    We consider the gravitational scattering of point particles in four dimensions, at Planckian centre of mass energy and low momentum transfer, or the eikonal approximation. The scattering amplitude can be exactly computed ...
  • Das, Saurya; Majumdar, Parthasarathi (American Physical SocietyInstitute of Mathematical Scienceshttps://doi.org/10.1103/PhysRevLett.72.2524, 1994)
    The amplitude for the scattering of a point magnetic monopole and a point charge, at center-of- mass energies much larger than the masses of the particles, and in the limit of low momentum transfer, is shown to be ...
  • Das, Saurya; Majumdar, Parthasarathi (American Physical SocietyInstitute of Mathematical SciencesInternational Centre for Theoretical Physicshttps://doi.org/10.1103/PhysRevD.51.5664, 1995)
    The scattering of pointlike particles at a very large center-of-mass energies and fixed low momentum transfers, occurring due to both their electromagnetic and gravitational interactions, is reexamined in the particular ...
  • Das, Saurya; Majumdar, Parthasarathi (Elsevier BV North HollandInstitute of Mathematical Sciences (India)International Centre for Theoretical Physics, 1995)
    We consider possible mixing of electromagnetic and gravitational shock waves, in the Planckian energy scattering of point particles in Minkowski space, By boosting a Reissner-Nordstriim black hole solution to the velocity ...
  • Das, Saurya; Majumdar, Parthasarathi (American Physical SocietyInstitute of Mathematical Sciences (India)https://doi.org/10.1103/PhysRevD.55.2090, 1997)
    Approximating light charged pointlike particles in terms of ~nonextremal! dilatonic black holes is shown to lead to certain pathologies in Planckian scattering in the eikonal approximation, which are traced to the presence ...
  • Das, Saurya; Dasgupta, Arundhati; Sarkar, Tapobrata (American Physical SocietyArts and ScienceInstitute of Mathematical Sciences (India)https://doi.org/10.1103/PhysRevD.55.7693, 1997)
    We study the emission of scalar particles from a class of near-extremal five-dimensional black holes and the corresponding D-brane configuration at high energies. We show that the distribution functions and the black hole ...
  • Das, Saurya; Majumdar, Parthasarathi (Indian Academy of SciencesInstitute of Mathematical Sciences (India)https://www.ias.ac.in/article/fulltext/pram/051/03-04/0413-0419, 1998)
    We discuss an approach to compute two-particle scattering amplitudes for spinless light particles colliding at Planckian centre-of-mass energies, with increasing momentum transfer away from the eikonal limit. The leading ...
  • Das, Saurya; Dasgupta, Arundhati (SISSAPennsylvania State UniversityInstitute of Mathematical Sciences (India), 1999)
    We study the emission rates of scalar, spinor and vector particles from a 5 dimensional black hole for arbitrary partial waves. The solution is lifted to 6 dimensions, and the near horizon BTZ S3 geometry of the black ...
  • Das, Saurya; Ghosh, Amit; Mitra, P. (American Physical SocietyPennsylvania State UniversitySaha Institute of Nuclear Physics (Kolkata, India)https://doi.org/10.1103/PhysRevD.63.024023, 2000)
    The statistical entropy of a Schwarzschild black string in five dimensions is obtained by counting the black string states which form a representation of the near-horizon conformal symmetry with a central charge. ...
  • Das, Saurya; Mann, Robert B. (SISSAPennsylvania State UniversityUniversity of Waterloohttp://iopscience.iop.org/1126-6708/2000/08/033, 2000)
    We compute the conserved charges for Kerr anti-de Sitter spacetimes in various dimensions using the conformal and the counterterm prescriptions. We show that the conserved charge corresponding to the global timelike ...
  • Das, Saurya; Kaul, Romesh K.; Majumdar, Parthasarathi (American Institute of PhysicsPennsylvania State UniversityThe Institute of Mathematical Sciences (India)https://doi.org/10.1103/PhysRevD.63.044019, 2001)
    A new entropy bound, tighter than the standard holographic bound due to Bekenstein, is derived for spacetimes with nonrotating isolated horizons from the quantum geometry approach, in which the horizon is described by ...
  • Das, Saurya; Gegenberg, J.; Husain, V. (American Physical SocietyUniversity of WinnipegUniversity of New Brunswickhttps://doi.org/10.1103/PhysRevD.64.065027, 2001)
    We describe a class of asymptotically AdS scalar field spacetimes, and calculate the associated conserved charges for three, four and five spacetime dimensions using the conformal and counterterm prescriptions. The energy ...
  • Barvinsky, Andrei; Das, Saurya; Kunstatter, Gabor (ElsevierLebedev Physics Institute and Lebedev Research Center in PhysicsUniversity of Winnipeg, 2001)
    We quantize the spherically symmetric sector of generic charged black holes. Thermal properties are incorporated by imposing periodicity in Euclidean time, with period equal to the inverse Hawking temperature of the black ...
  • Das, Saurya; Kobes, Randy; Kunstatter, Gabor (American Physical SocietyUniversity of WinnipegWinnipeg Institute for Theoretical Physicshttps://doi.org/10.1103/PhysRevA.65.062310, 2002)
    We show that by a suitable choice of a time-dependent Hamiltonian, Deutsch’s algorithm can be implemented by an adiabatic quantum computer. We extend our analysis to the Deutsch-Jozsa problem and estimate the required ...
  • Das, Saurya; Ramadevi, P.; Yajnik, U. A.; Sule, A. (ElsevierUniversity of New BrunswickIndian Institute of Technology Bombay, 2003)
    It has been argued by several authors, using different formalisms, that the quantum mechanical spectrum of black hole horizon area is discrete and uniformly spaced. Recently it was shown that two such approaches, namely ...
  • Bernard-Salas, J.; Habart, E.; Arab, H.; Abergel, A.; Dartois, E.; Martin, P.; Bontemps, S.; Joblin, C.; White, G. J.; Bernard, J.-P.; Naylor, David A. (EDP SciencesArts and ScienceDepartment of Physics & AstronomyInstitut d'Astrophysique SpatialeCanadian Institute for Theoretical AstrophysicsLaboratoire d'Astrophysique de BordeauxUniversité de ToulouseIRAPOpen UniversityRutherford Appleton LaboratoryUniversity of Lethbridgehttps://dx.doi.org/10.1051/0004-6361/201118083, 2012)
    Context. The energetics in photo-dissociation regions (PDRs) are mainly regulated by the balance between the heating from the photo-electric effect acting on dust grains, and the cooling via the copious emission of photons ...
  • Greve, T. R.; Leonidaki, I.; Xilouris, E.M.; Weiss, A.; Zhang, Z.-Y.; van der Werf, P.; Aalto, S.; Armus, L.; Diaz-Santos, T.; Evans, A.S.; Fischer, J.; Gao, Y.; Gonzalez-Alfonso, E.; Harris, A.; Henkel, C.; Mekjerink, R.; Naylor, David A.; Smith, H.A.; Spaans, M.; Stacey, G.J.; Veilleux, S.; Walter, F. (American Astronomical Society, 2014)
    We present FIR[50-300 um]-CO luminosity relations (i.e., log Lfir = a log L’co + B) for the full CO rotational ladder from J = 1 – 0 up to J = 13 -12 for a sample of 62 local (z <= 0.1) (Ultra) Luminous Infrared Galaxies ...
  • van der Wiel, M. H. D.; Naylor, David A.; Kamp, I.; Ménard, F.; Thi, W.-F.; Woitke, P.; Olofsson, G.; Pontoppidan, K. M.; Di Francesco, J.; Glauser, A. M.; Greaves, J. S.; Ivison, R. J. (Oxford University PressArts and ScienceDepartment of Physics and AstronomyUniversity of LethbridgeUniversity of GroningenCNRSUniversité Grenoble AlpesUniversity of St. AndrewsStockholm UniversitySpace Telescope Science InstituteNational Research Council CanadaUniversity of VictoriaETH ZurichEuropean Southern ObservatoryUniversity of Edinburghhttps://doi.org/10.1093/mnras/stu1462, 2014)
    Molecular gas constitutes the dominant mass component of protoplanetary discs. To date, these sources have not been studied comprehensively at the longest far-infrared and shortest submillimetre wavelengths. This paper ...
  • Swinyard, B. M.; Polehampton, E. T.; Hopwood, R.; Valtchanov, I.; Lu, N.; Fulton, T.; Benielli, D.; Imhof, P.; Marchili, N.; Baluteau, J.-P.; Bendo, G. J.; Ferlet, M.; Griffin, M. J.; Lim, T. L.; Makiwa, G.; Naylor, David A.; Orton, G. S.; Papageorgiou, A.; Pearson, C. P.; Schulz, B.; Sidher, S. D.; Spencer, L. D.; van der Wiel, M. H. D.; Wu, R. (Oxford University PressArts and ScienceDepartment of Physics and AstronomyUniversity College LondonRutherford Appleton LaboratoryUniversity of LethbridgeImperial College LondonEuropean Space Astronomy Centre (Spain)California Institute of TechnologyBlue Sky SpectroscopyUniversité d'Aix-MarseilleCNRSUniversità di PadovaUniversity of ManchesterCardiff UniversityThe Open Universityhttps://doi.org/10.1093/mnras/stu409, 2014)
    The Herschel Spectral and Photometric REceiver (SPIRE) instrument consists of an imaging photometric camera and an imaging Fourier Transform Spectrometer (FTS), both operating over a frequency range of∼450–1550GHz. In this ...
  • Kohler, M.; Habart, E.; Arab, H.; Bernard-Salas, J.; Ayasso, H.; Abergel, A.; Zavagno, A.; Polehampton, E.; van der Wiel, M.H.D.; Naylor, David A.; Makiwa, Gibion; Dassas, K.; Joblin, C.; Pilleri, P.; Berne, O.; Fuente, A.; Gerin, M.; Goicoechea, J.R.; Teyssier, D. (EDP Sciences10.1051/0004-6361/201322711, 2014)
    Context. The determination of the physical conditions in molecular clouds is a key step towards our understanding of their formation and evolution of associated star formation. We investigate the density, temperature, and ...