Abstract
We discuss the issue of unitarity in particular quantum cosmological models with scalar fields. The time variable is recovered, in this context, by using the Schutz formalism for a radiative fluid. Two cases are considered: a phantom scalar field and an ordinary scalar field. For the first case, it is shown that the evolution is unitary provided a convenient factor ordering and inner product measure are chosen; the same happens for the ordinary scalar field, except for some special cases in which the Hamiltonian is not self-adjoint but admits a self-adjoint extension. In all cases, even in the cases not exhibiting a unitary evolution, a formal computation of the expectation value of the scale factor indicates a nonsingular bounce. The importance of unitary evolution in quantum cosmology is briefly discussed.
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Almeida, C.R., Batista, A.B., Fabris, J.C. et al. Quantum cosmology with scalar fields: Self-adjointness and cosmological scenarios. Gravit. Cosmol. 21, 191–199 (2015). https://doi.org/10.1134/S0202289315030020
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DOI: https://doi.org/10.1134/S0202289315030020