标题： 衰变真空密度的 Friedmann 宇宙学 显示英文标题

标题： Friedmann cosmology with decaying vacuum density

摘要： 在解决观测到的宇宙学常数的小值与量子场论得出的巨大值之间不兼容问题的若干提议中，我们可以找到真空能量密度衰减的想法，它从早期宇宙演化时的高值逐渐减少到现在观测到的小值。 本文考虑了Schutzhold最近基于弯曲、膨胀背景下的量子场估计提出的真空密度变化规律，该规律的特点是真空密度与哈勃参数成正比。 我们证明，在一个各向同性且均匀、空间平坦的模型背景下，相应的解保留了标准宇宙学已确立的特征，并且还与观测到的宇宙学参数一致。 我们的场景呈现了一个由辐射主导的初始阶段，随后是一个足够长的尘埃时代以允许结构形成，接着是一个由宇宙项主导的时代，最终渐近趋于一个de Sitter宇宙。 取物质密度等于真空能量密度的一半（如观测所建议），我们得到的宇宙年龄为Ht=1.1，减速参数等于-1/2。 显示英文摘要

摘要： Among the several proposals to solve the incompatibility between the observed small value of the cosmological constant and the huge value obtained by quantum field theories, we can find the idea of a decaying vacuum energy density, leading from high values at early times of universe evolution to the small value observed nowadays. In this paper we consider a variation law for the vacuum density recently proposed by Schutzhold on the basis of quantum field estimations in the curved, expanding background, characterized by a vacuum density proportional to the Hubble parameter. We show that, in the context of an isotropic and homogeneous, spatially flat model, the corresponding solutions retain the well established features of the standard cosmology, and, in addition, are in accordance with the observed cosmological parameters. Our scenario presents an initial phase dominated by radiation, followed by a dust era long enough to permit structure formation, and by an epoch dominated by the cosmological term, which tends asymptotically to a de Sitter universe. Taking the matter density equals to half of the vacuum energy density, as suggested by observation, we obtain a universe age given by Ht = 1.1, and a decelerating parameter equals to -1/2.