标题： 标量场的量子宇宙学：自伴性和宇宙学场景 显示英文标题

标题： Quantum cosmology with scalar fields: self-adjointness and cosmological scenarios

摘要： 我们讨论了在特定量子宇宙学模型中标量场的单位性问题。在此背景下，通过使用Schutz关于辐射流体的形式主义恢复了时间变量。考虑了两种情况：幻影标量场和普通标量场。对于第一种情况，表明只要选择适当的因子排序和内积测度，演化就是幺正的；对于普通标量场，同样如此，除了某些特殊情况下哈密顿算符不是自伴的但存在自伴延拓的情况。在所有情况下，即使对于那些不表现出幺正演化的案例，标度因子期望值的正式计算也表明存在非奇异反弹。量子宇宙学中幺正演化的的重要性被简要讨论。 显示英文摘要

摘要： We discuss the issue of unitarity in particular quantum cosmological models with scalar field. The time variable is recovered, in this context, by using the Schutz's 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 for which the Hamiltonian is not self-adjoint but admits a self-adjoint extension. In all cases, even for those cases not exhibiting unitary evolution, the formal computation of the expectation value of the scale factor indicates a non-singular bounce. The importance of the unitary evolution in quantum cosmology is briefly discussed.