scholarly journals Scattering Theory for Klein–Gordon Equations with Non-Positive Energy

2011 ◽  
Vol 13 (4) ◽  
pp. 883-941 ◽  
Author(s):  
Christian Gérard
Keyword(s):  
Scattering Theory ◽  
Positive Energy ◽  
Klein Gordon

HADAMARD STATES, ADIABATIC VACUA AND THE CONSTRUCTION OF PHYSICAL STATES FOR SCALAR QUANTUM FIELDS ON CURVED SPACETIME

1996 ◽  
Vol 08 (08) ◽  
pp. 1091-1159 ◽  
Author(s):  
WOLFGANG JUNKER
Keyword(s):  
Pseudodifferential Operators ◽  
Cauchy Surface ◽  
Positive Energy ◽  
Hyperbolic Spacetime ◽  
Vacuum States ◽  
Mathematical Review ◽  
Scalar Quantum ◽  
Klein Gordon ◽  
Hadamard States ◽  
Adiabatic Vacuum

Quasifree states of a linear Klein-Gordon quantum field on globally hyperbolic spacetime manifolds are considered. After a short mathematical review techniques from the theory of pseudodifferential operators and wavefront sets on manifolds are used to develop a criterion for a state to be an Hadamard state. It is proven that ground- and KMS-states on certain static spacetimes and adiabatic vacuum states on Robertson-Walker spaces are Hadamard states. A counterexample is given which shows that the idea of instantaneous positive energy states w.r.t. a Cauchy surface does in general not yield physical states. Finally, the problem of constructing Hadamard states on arbitrary curved spacetimes is solved in principle.

THE KLEIN–GORDON EQUATION WITH A COULOMB PLUS SCALAR POTENTIAL IN D DIMENSIONS

2004 ◽  
Vol 13 (03) ◽  
pp. 597-610 ◽  
Author(s):  
ZHONG-QI MA ◽  
SHI-HAI DONG ◽  
XIAO-YAN GU ◽  
JIANG YU ◽  
M. LOZADA-CASSOU
Keyword(s):  
Angular Momentum ◽  
Quantum Number ◽  
Coulomb Potential ◽  
Gordon Equation ◽  
Scalar Potential ◽  
Positive Energy ◽  
Angular Momentum Quantum Number ◽  
Klein Gordon ◽  
Klein Gordon Equation

The solutions of the Klein–Gordon equation with a Coulomb plus scalar potential in D dimensions are exactly obtained. The energy E(n,l,D) is analytically presented and the dependence of the energy E(n,l,D) on the dimension D is analyzed in some detail. The positive energy E(n,0,D) first decreases and then increases with increasing dimension D. The positive energy E(n,l D)(l≠0) increases with increasing dimension D. The dependences of the negative energies E(n,0,D) and E(n,l,D)(l≠0) on the dimension D are opposite to those of the corresponding positive energies E(n,0,D) and E(n,l,D)(l≠0). It is found that the energy E(n,0,D) is symmetric with respect to D=2 for D∈(0,4). It is also found that the energy E(n,l,D)(l≠0) is almost independent of the angular momentum quantum number l for large D and is completely independent of the angular momentum quantum number l if the Coulomb potential is equal to the scalar one. The energy E(n,l D) is almost overlapping for large D.

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