论文标题
宇宙学恒定问题和在扩展的宇宙中进行真空
The Cosmological Constant Problem and Running Vacuum in the Expanding Universe
论文作者
论文摘要
众所周知，量子场理论（QFT）引起了宇宙常数$λ$的巨大价值，这与宇宙学的观察非常不一致。我们在这里审查了这个基本理论难题的某些方面（“宇宙恒定问题”），并强烈主张宇宙真空密度$ρ_ {\ rm vac} $可能会随着膨胀率$ h $的膨胀率而有可能发生略微演变。这样的“运行真空模型”（RVM）提案可以预测有效的动态暗能量，而无需假设新的临时场（典型范围）。使用曲线时空中QFT中绝热翻新的方法，我们发现$ρ_ {\ rm vac}（h）$获取了由量子物质效应引起的动态组件$ {\ cal o}（h^2）$。还有$ {\ cal o}（h^n）$（$ n = 4,6，.. $）贡献，其中一些可能会触发早期宇宙的通货膨胀。值得注意的是，绝热重新归一化的$ρ_ {\ rm vac}（h）$的演变不受与群体（$ \ sim m^4 $）的四分之一的危险术语的影响。传统上，这些术语是麻烦的主要来源，因为它们负责宇宙恒定问题的极端微调特征。但是，在研究的上下文中，$ρ_{\ rm vac}（h）$ ago $ h_0 $的$由一个主术语（$ρ_{\ rm vac} 0 $）加上上述轻度动态组件$ \ propto $ \ proptov（H^2-H_0^2）$（$ | | | | | | |精髓。最后，在现象学方面，我们表明，RVM可能会减轻一些困扰“一致性” $λ$ CDM模型的观察性一致性，例如$ h_0 $ h_0 $ and $σ_8$ tensions of the of concordance'$λ$ CDM模型。
It is well-known that quantum field theory (QFT) induces a huge value of the cosmological constant, $Λ$, which is outrageously inconsistent with cosmological observations. We review here some aspects of this fundamental theoretical conundrum (`the cosmological constant problem') and strongly argue in favor of the possibility that the cosmic vacuum density $ρ_{\rm vac}$ may be mildly evolving with the expansion rate $H$. Such a `running vacuum model' (RVM) proposal predicts an effective dynamical dark energy without postulating new ad hoc fields (quintessence and the like). Using the method of adiabatic renormalization within QFT in curved spacetime we find that $ρ_{\rm vac}(H)$ acquires a dynamical component ${\cal O}(H^2)$ caused by the quantum matter effects. There are also ${\cal O}(H^n)$ ($n=4,6,..$) contributions, some of which may trigger inflation in the early universe. Remarkably, the evolution of the adiabatically renormalized $ρ_{\rm vac}(H)$ is not affected by dangerous terms proportional to the quartic power of the masses ($\sim m^4$) of the fields. Traditionally, these terms have been the main source of trouble as they are responsible for the extreme fine tuning feature of the cosmological constant problem. In the context under study, however, the late time $ρ_{\rm vac}(H)$ around $H_0$ is given by a dominant term ($ρ_{\rm vac}^0$) plus the aforementioned mild dynamical component $\propto ν(H^2-H_0^2)$ (with $|ν|\ll1$), which makes the RVM to mimic quintessence. Finally, on the phenomenological side we show that the RVM may be instrumental in alleviating some of the most challenging problems (so-called `tensions') afflicting nowadays the observational consistency of the `concordance' $Λ$CDM model, such as the $H_0$ and $σ_8$ tensions.
