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Topologically massive planar universes with constant twist
ANNALS
OF PHYSICS
176, 182 (1987)
Abstracts
of Papers
to Appear
in Future
Issues
Topologically Massive Planar Universes with Consrant Twist. R. PERCACCI. P. SODANO. Center for Theoretical Physics, Laboratory for Nuclear Science and Department Massachusetts Institute of Technology, Cambridge, Massachusetts 02139. We derive the general form of the topologically found that all these metrics have a nonvanishing with constant twist and show their isometrics.
massive Einstein twist. We then
AND
I. VUORIO.
of Physics,
equations for stationary metrics. It is provide the complete set of solutions
Delta-Hole Approach to Pion Double Charge E.whange. T. KARAPIPEKIS. Schweizerisches Institut Nuklearforschung (S.I.N.), CH, 5234 Villigen, Switzerland; AND M. KOBAYASHI. Institut Kernphysik, Joh. Gutenberg-Universitlt, D, 6500 Main,, Federal Republic of Germany Schweizerisches Institut fiir Nuklearforschung (S.I.N.), CH, 5234 Villigen, Switzerland.
fur fur and
We present a semi-microscopic model for the double charge exchange (DCX) reaction (x +, B ) to the ground state of the final nucleus at medium and low energies. We separate the DCX amplitude into a sequential and a non-sequential part, with pions distorted by the full d-hole optical potential and medium corrections to the resonant n--N amplitude taken into account partly microscopically (d propagation and binding, Pauli blocking) and partly phenomenologically (spreading potential). In the non-sequential part of the amplitude charge exchange takes place between the d and a nucleon via a phenomenological A -N interaction. We find that the sequential amplitude alone provides an adequate description of the reaction at low energies (where it proceeds predominantly via non-analog intermediate states). At higher energies the short-range d - N interaction begins to play a more important role and the non-sequential amplitude interferes delicately with the sequential one. We are able to describe the DCX reaction well for “‘C at all energies, for I60 up to resonance and for ‘*O at 50 MeV, but we are not able to reproduce the energy and angular dependence of the IgO cross-section in the medium energy region.
Fundamental Functions in Equilibrium Thermodynamics. H. J. TER HORST. Department State University Utrecht, Croesestraat 77A, 3522 AD Utrecht, The Netherlands.
of Chemistry,
In the standard presentations of the fundamentals of Gibbsian equilibrium thermodynamics one can find several gaps in the logic. For a subject that is as widely used as equilibrium thermodynamics, it is of interest to clear up such questions of mathematical rigor. In this paper it is shown that using convex analysis one can give a mathematically rigorous treatment of several basic aspects of equilibrium thermodynamics. On the basis of a fundamental convexity property implied by the second law, the following topics are discussed: thermodynamic stability, transformed fundamental functions (such as the Gibbs free energy), and the existence and uniqueness of possible linal equilibrium states of closed composite thermodynamic systems. It is shown that a standard mathematical characterization of thermodynamic stability (involving a positive deliniteness property) is sufficient but in fact not necessary for the physically superior convexity characterization of thermodynamic stability. Furthermore, it is found that functions such as the Gibbs free energy can be rigorously and globally defined using convex conjugation instead of Legendre transformation, Another result described in this paper is that equilibrium thermodynamics cannot always uniquely predict possible tinal equilibrium states of closed composite thermodynamic systems. 0003-4916/87 Copyright All rights
$7.50
0 1987 by Academic Press, Inc. of reproduction in any form reserved.
OF PHYSICS
176, 182 (1987)
Abstracts
of Papers
to Appear
in Future
Issues
Topologically Massive Planar Universes with Consrant Twist. R. PERCACCI. P. SODANO. Center for Theoretical Physics, Laboratory for Nuclear Science and Department Massachusetts Institute of Technology, Cambridge, Massachusetts 02139. We derive the general form of the topologically found that all these metrics have a nonvanishing with constant twist and show their isometrics.
massive Einstein twist. We then
AND
I. VUORIO.
of Physics,
equations for stationary metrics. It is provide the complete set of solutions
Delta-Hole Approach to Pion Double Charge E.whange. T. KARAPIPEKIS. Schweizerisches Institut Nuklearforschung (S.I.N.), CH, 5234 Villigen, Switzerland; AND M. KOBAYASHI. Institut Kernphysik, Joh. Gutenberg-Universitlt, D, 6500 Main,, Federal Republic of Germany Schweizerisches Institut fiir Nuklearforschung (S.I.N.), CH, 5234 Villigen, Switzerland.
fur fur and
We present a semi-microscopic model for the double charge exchange (DCX) reaction (x +, B ) to the ground state of the final nucleus at medium and low energies. We separate the DCX amplitude into a sequential and a non-sequential part, with pions distorted by the full d-hole optical potential and medium corrections to the resonant n--N amplitude taken into account partly microscopically (d propagation and binding, Pauli blocking) and partly phenomenologically (spreading potential). In the non-sequential part of the amplitude charge exchange takes place between the d and a nucleon via a phenomenological A -N interaction. We find that the sequential amplitude alone provides an adequate description of the reaction at low energies (where it proceeds predominantly via non-analog intermediate states). At higher energies the short-range d - N interaction begins to play a more important role and the non-sequential amplitude interferes delicately with the sequential one. We are able to describe the DCX reaction well for “‘C at all energies, for I60 up to resonance and for ‘*O at 50 MeV, but we are not able to reproduce the energy and angular dependence of the IgO cross-section in the medium energy region.
Fundamental Functions in Equilibrium Thermodynamics. H. J. TER HORST. Department State University Utrecht, Croesestraat 77A, 3522 AD Utrecht, The Netherlands.
of Chemistry,
In the standard presentations of the fundamentals of Gibbsian equilibrium thermodynamics one can find several gaps in the logic. For a subject that is as widely used as equilibrium thermodynamics, it is of interest to clear up such questions of mathematical rigor. In this paper it is shown that using convex analysis one can give a mathematically rigorous treatment of several basic aspects of equilibrium thermodynamics. On the basis of a fundamental convexity property implied by the second law, the following topics are discussed: thermodynamic stability, transformed fundamental functions (such as the Gibbs free energy), and the existence and uniqueness of possible linal equilibrium states of closed composite thermodynamic systems. It is shown that a standard mathematical characterization of thermodynamic stability (involving a positive deliniteness property) is sufficient but in fact not necessary for the physically superior convexity characterization of thermodynamic stability. Furthermore, it is found that functions such as the Gibbs free energy can be rigorously and globally defined using convex conjugation instead of Legendre transformation, Another result described in this paper is that equilibrium thermodynamics cannot always uniquely predict possible tinal equilibrium states of closed composite thermodynamic systems. 0003-4916/87 Copyright All rights
$7.50
0 1987 by Academic Press, Inc. of reproduction in any form reserved.