• Volume 45, Issue 2

      August 1995,   pages  91-219

    • Generalized Fock spaces, new forms of quantum statistics and their algebras

      A K Mishra G Rajasekaran

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      We formulate a theory of generalized Fock spaces which underlies the different forms of quantum statistics such as ‘infinite’, Bose-Einstein and Fermi-Dirac statistics. Single-indexed systems as well as multi-indexed systems that cannot be mapped into single-indexed systems are studied. Our theory is based on a three-tiered structure consisting of Fock space, statistics and algebra. This general formalism not only unifies the various forms of statistics and algebras, but also allows us to construct many new forms of quantum statistics as well as many algebras of creation and destruction operators. Some of these are: new algebras for infinite statistics,q-statistics and its many avatars, a consistent algebra for fractional statistics, null statistics or statistics of frozen order, ‘doubly-infinite’ statistics, many representations of orthostatistics, Hubbard statistics and its variations.

    • Time dependent canonical perturbation theory I: General theory

      B R Sitaram Mitaxi P Mehta

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      In this communication, we reanalyze the causes of the singularities of canonical perturbation theory and show that some of these singularities can be removed by using time-dependent canonical perturbation theory. A study of the local and global properties (in terms of the perturbation parameter) is also undertaken.

    • Time dependent canonical perturbation theory II: Application to the Henon-Heiles system

      Mitaxi P Mehta B R Sitaram

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      In this communication, we report the results of the application of time-dependent perturbation theory to the Henon-Heiles system. We show that the predictions of the perturbation theory hold good for short times, and try to explain the increase of error in the predicted results with the increase in energy.

    • The Coulomb Green’s function revisited

      S S Vasan M Seetharaman

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      It is demonstrated how the energy-dependent Green’s function for the Schrödinger-Coulomb problem can be deduced from a knowledge of the harmonic oscillator time-propagator. All the known results of the Coulomb system are shown to be elegantly derivable from such a connection.

    • Gravitational and electromagnetic fields of a charged tachyon

      K S Virbhadra

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      An axially symmetric exact solution of the Einstein-Maxwell equations is obtained and is interpreted to give the gravitational and electromagnetic fields of a charged tachyon. Switching off the charge parameter yields the solution for the uncharged tachyon which was earlier obtained by Vaidya. The null surfaces for the charged tachyon are discussed.

    • A radiating dyon solution

      A Chamorro K S Virbhadra

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      We give a non-static exact solution of the Einstein-Maxwell equations (with null fluid), which is a non-static magnetic charge generalization to the Bonnor-Vaidya solution and describes the gravitational and electromagnetic fields of a non-rotating massive radiating dyon. In addition, using the energy-momentum pseudotensors of Einstein and Landau and Lifshitz we obtain the energy, momentum, and power output of the radiating dyon and find that both prescriptions give the same result.

    • Static models of cosmic strings in general relativity

      G P Singh

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      Exact solutions to Einstein’s equations for a cloud of massive strings with a general static metric representing spherical plane and hyperbolic symmetries are derived. Some properties of massive strings for different cases are also discussed.

    • Neutrino emissivity of quark matter at finite temperatures

      V K Gupta A Wadhwa J D Anand

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      We evaluate the emissivity rates for d-decay and s-decay by exactly solving the angular integrals involved and without assuming the degeneracy of electrons. We have also studied the effects of QCD coupling constant as well as the s-quark mass on the emissivity rates. We find that these parameters are important in determining the threshold and extinction densities for d- and s-decays.

    • Search for theχc charmonium states as solution to the CDFψ′ puzzle

      S F Tuan

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      The efforts of Roy-Sridhar-Close-Cho-Wise-Trivedi to resolve the CDFψ′ anomaly with cascades from above-thresholdχc states require well defined signatures [a small total width and a large branching fraction forχcJγ+ψ′] for the solution to be viable. Here we estimate the production of such states from BR(BχcJ+X)BR(χcJγψ′) andγγ production ofχc2 at CLEO II, and comment on the feasibility of testing the hypothesis in terms of current experimental capabilities.

    • Energy and momentum of cylindrical gravitational waves-II

      K S Virbhadra

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      Recently Rosen and the present author obtained the energy and momentum densities of cylindrical gravitational waves in Einstein’s prescription and found them to be finite and reasonable. In the present paper we calculate the same in the prescriptions of Tolman as well as Landau and Lifshitz and discuss the results.

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