Browsing Physics & Astronomy by Title

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  • 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 (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; Shankaranarayanan, S. (Arts and ScienceDepartment of PhysicsUniversity of LethbridgeMax-Planck-Institut für Gravitationphysikhttps://doi.org/10.1088/1742-6596/68/1/012015, 2015-12-16)
    We review aspects of black hole thermodynamics, and show how entanglement of a quantum field between the inside and outside of a horizon can account for the areaproportionality of black hole entropy, provided the field ...
  • Braunstein, Samuel L.; Das, Saurya; Shankaranarayanan, S. (Arts and ScienceDepartment of PhysicsUniversity of YorkUniversity of LethbridgeIndian Institute of Science Education and Research, 2015-12-15)
    It has long been conjectured that the entropy of quantum fields across boundaries scales as the boundary area. This conjecture has not been easy to test in spacetime dimensions greater than four because of divergences ...
  • Makiwa, G.; Naylor, David A.; van der Wiel, M. H. D.; Ward-Thompson, D.; Kirk, J. M.; Eyres, S.; Abergel, A.; Köhler, M. (Oxford University PressArts and ScienceDepartment of Physics and AstronomyUniversity of LethbridgeUniversity of CopenhagenUniversity of Central LancashireUniversité Paris SudCNRSQueen Mary University of Londonhttps://doi.org/10.1093/mnras/stw428, 2016)
    Dust grains play a key role in the physics of star-forming regions, even though they constitute only ∼1 per cent of the mass of the interstellar medium. The derivation of accurate dust parameters such as temperature (Td), ...
  • Balasubramanian, Venkat; Das, Saurya; Vagenas, Elias C. (Arts and ScienceDepartment of Physics and AstronomyUniversity of Western OntarioUniversity of LethbridgeKuwait Universityhttps://doi.org/10.1016/j.aop.2015.04.033, 2015-12-16)
    In this work we explore the self-adjointness of the GUP-modified momentum and Hamiltonian oper- ators over different domains. In particular, we utilize the theorem by von-Newmann for symmetric operators in order to ...
  • Vagenas, Elias C.; Das, Saurya (Arts and ScienceDepartment of PhysicsUniversity of AthensUniversity of Lethbridge, 2016-01-06)
    Motivated by the recent work of Robinson and Wilczek, we evaluate the gravitational anomaly of a chiral scalar field in a Vaidya spacetime of arbitrary mass function, and thus the outgoing flux from the time-dependent ...
  • Das, Saurya; Robinson, Sean P.; Vagenas, Elias C. (Arts and ScienceDepartment of PhysicsUniversity of LethbridgeMassachusetts Institute of TechnologyUniversity of Athens, 2016-01-07)
    We explore the method of Robinson andWilczek for deriving the Hawking temperature of a black hole. In this method, the Hawking radiation restores general covariance in an effective theory of near-horizon physics which ...
  • Das, Saurya; Gegenberg, Jack (Arts and ScienceDepartment of PhysicsUniversity of LethbridgeUniversity of New Brunswickhttps://doi.org/10.1007/s10714-008-0619-3, 2016-01-25)
    We derive general conditions under which geodesics of stationary spacetimes resemble trajectories of charged particles in an electromagnetic field. For large curvatures (analogous to strong magnetic fields), the quantum ...
  • 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; Shankaranarayanan, S. (Arts and ScienceDepartment of PhysicsUniversity of LethbridgeThe Abdus Salam International Centre for Theoretical Physicshttps://doi.org/10.1088/0264-9381/22/3/L01, 2015-12-23)
    We compute the high frequency quasi-normal modes (QNM) for scalar perturbations of spherically symmetric single horizon black-holes in (D+2)-space-time dimensions with generic curvature singularities and having metrics ...
  • Ghosh, Archisman; Shankaranarayanan, S.; Das, Saurya (Arts and ScienceDepartment of PhysicsIndian Institute of Technology KanpurThe Abdus Salam International Centre for Theoretical PhysicsUniversity of Lethbridgehttps://doi.org/10.1088/0264-9381/23/6/003, 2016-01-05)
    The possibility that the asymptotic quasi-normal mode (QNM) frequencies can be used to obtain the Bekenstein-Hawking entropy for the Schwarzschild black hole — commonly referred to as Hod’s conjecture — has received ...
  • Cavagalià, Marco; Das, Saurya (Arts and ScienceDepartment of PhysicsUniversity of MississippiUniversity of Lethbridgehttps://doi.org/10.1088/0264-9381/21/19/001, 2015-12-23)
    We show that the Hawking temperature and the entropy of black holes are subject to corrections from two sources: the generalized uncertainty principle and thermal fluctuations. Both effects increase the temperature and ...
  • Das, Saurya; Shankaranarayanan, S. (Arts and ScienceDepartment of PhysicsUniversity of LethbridgeInternational Centre for Theoretical Physicshttps://doi.org/10.1103/PhysRevD.73.121701, 2016-01-25)
    We revisit the problem of finding the entanglement entropy of a scalar field on a lattice by tracing over its degrees of freedom inside a sphere. It is known that this entropy satisfies the area law – entropy proportional ...
  • Ahmadi, Morteza; Das, Saurya; Shankaranarayanan, S. (Arts and ScienceDepartment of PhysicsUniversity of LethbridgeInternational Centre for Theoretical Physicshttps://doi.org/10.1139/p06-002, 2016-01-25)
    It is known that the entanglement entropy of a scalar field, found by tracing over its degrees of freedom inside a sphere of radius R, is proportional to the area of the sphere (and not its volume). This suggests that ...
  • Bhaduri, Rajat K.; Tran, Muoi N.; Das, Saurya (Arts and ScienceDepartment of PhysicsMcMaster UniversityUniversity of Lethbridgehttps://doi.org/10.1103/PhysRevD.69.104018, 2016-01-25)
    It has been suggested recently that the microcanonical entropy of a system may be accurately reproduced by including a logarithmic correction to the canonical entropy. In this paper we test this claim both analytically ...
  • Sur, Sourav; Das, Saurya (Arts and ScienceDepartment of PhysicsUniversity of Lethbridgehttps://doi.org/10.1088/1475-7516/2009/01/007, 2015-12-15)
    We investigate models of dark energy with purely kinetic multiple k- essence sources that allow for the crossing of the phantom divide line, without violating the conditions of stability. It is known that with more than ...
  • 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; Vagenas, Elias C. (Arts and ScienceDepartment of PhysicsUniversity of LethbridgeAcademy of Athenshttps://doi.org/10.1139/P08-105, 2016-01-18)
    Various theories of Quantum Gravity argue that near the Planck scale, the Heisenberg Uncertainty Principle should be replaced by the so called Generalized Uncertainty Principle (GUP).We show that the GUP gives rise to ...
  • 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 ...