Axion-induced topology change in quantum gravity and string theory
1988; Elsevier BV; Volume: 306; Issue: 4 Linguagem: Inglês
10.1016/0550-3213(88)90446-4
ISSN1873-1562
AutoresSteven B. Giddings, Andrew Strominger,
Tópico(s)Black Holes and Theoretical Physics
ResumoWe consider a system comprised of an axion (described by a rank-three antisymmetric tensor field strength) coupled to gravity. Instantons are found which describe the nucleation of a Planck-sized baby Robertson-Walker universe. Information loss to the baby universe can lead to an effective loss of quantum coherence. An estimate of the magnitude of this effect on particle propagation is made in the semi-classical approximation. This magnitude depends on the parameters of the theory (which includes a cutoff since the theory is non-renormalizable) and on the quantum state of the many-universe system. In contrast to the naive expectation that Planck-scale dynamics should lead to very small effects at low energies, the effects of these instantons can be large. The case of string theory is considered in some detail, and it is found that a massless dilaton can suppress the tunneling.
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