Phys.Rev.D57:2219-2229,1998 The low energy effective actions which arise from string theory or M-theory
are considered in the cosmological context, where the graviton, dilaton and
antisymmetric ...tensor field strengths depend only on time. We show that previous
results can be extended to include cosmological solutions that are related to
the E_N Toda equations. The solutions of the Wheeler-DeWitt equation in
minisuperspace are obtained for some of the simpler cosmological models by
introducing intertwining operators that generate canonical transformations
which map the theories into free theories. We study the cosmological properties
of these solutions, and also briefly discuss generalised Brans-Dicke models in
our framework. The cosmological models are closely related to p-brane solitons,
which we discuss in the context of the E_N Toda equations. We give the explicit
solutions for extremal multi-charge (D-3)-branes in the truncated system
described by the D_4 =O(4,4) Toda equations.
The S-duality invariance of the equations of motion of four dimensional string effective action with cosmological constant, \(\Lambda \), is studied. It is demonstrated that the S-duality symmetry of ...the field equations are broken for nonzero \(\Lambda\). The ``naturalness'' hypothesis is invoked to argue that \(\Lambda \) should remain small since exact S-duality symmetry will force the cosmological constant to vanish in the string effective action.
The significance of the Wess--Zumino term in spin tunneling is explored, and a formula is established for the splitting of energy levels of a particle with large fermionic spin as an applied magnetic ...field is switched on.
The low energy effective actions which arise from string theory or M-theory are considered in the cosmological context, where the graviton, dilaton and antisymmetric tensor field strengths depend ...only on time. We show that previous results can be extended to include cosmological solutions that are related to the E_N Toda equations. The solutions of the Wheeler-DeWitt equation in minisuperspace are obtained for some of the simpler cosmological models by introducing intertwining operators that generate canonical transformations which map the theories into free theories. We study the cosmological properties of these solutions, and also briefly discuss generalised Brans-Dicke models in our framework. The cosmological models are closely related to p-brane solitons, which we discuss in the context of the E_N Toda equations. We give the explicit solutions for extremal multi-charge (D-3)-branes in the truncated system described by the D_4 =O(4,4) Toda equations.
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