arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1408.5002hep-thastro-ph.COgr-qchep-ph
收藏

EFT超越地平线:随机暴胀和原始量子涨落如何走向经典

EFT Beyond the Horizon: Stochastic Inflation and How Primordial Quantum Fluctuations Go Classical

C. P. Burgess, R. Holman, G. Tasinato, M. Williams

摘要:

我们确定了描述暴胀超哈勃尺度的有效理论,并证明它是适用于开放系统的有效场论的特殊情况。开放系统允许在感兴趣的自由度和那些被整合出来的自由度之间交换信息,例如通过流体移动的粒子。严格地说,它们一般不能用有效拉格朗日量来描述;相反,适当的“低能”极限是描述慢自由度的密度矩阵演变的林德布拉德方程。我们导出了近德西特时空中量子场的超哈勃模方程,并得到了两个结果。我们表明,对角密度矩阵元素的演变迅速接近Starobinsky的随机暴胀图片的福克-普朗克方程。这提供了一个替代的第一原理推导这张图片的随机噪声和漂移,以及其领先的校正。(An应用程序计算具有亚光速声速的系统的噪声。)我们认为,相互作用的存在驱动器的非对角密度矩阵元素为零的字段的基础。这说明了为什么场基是原初量子涨落退相干的“指针基”,而它们在视界之外,从而允许它们作为经典涨落重新进入,正如分析CMB数据时所假设的那样。退相干过程是有效的,发生在几个哈勃时间后,即使是像引力强度这样弱的相互作用。至关重要的是,相互作用的细节在很大程度上只控制退相干时间,而不是最终的后期随机状态的性质,就像相互作用可以控制热系统的平衡时间,但在很大程度上与所产生的平衡态的性质无关。

英文摘要:

We identify the effective theory describing inflationary super-Hubble scales and show it to be a special case of effective field theories appropriate to open systems. Open systems allow information to be exchanged between the degrees of freedom of interest and those that are integrated out, such as for particles moving through a fluid. Strictly speaking they cannot in general be described by an effective lagrangian; rather the appropriate `low-energy' limit is instead a Lindblad equation describing the evolution of the density matrix of the slow degrees of freedom. We derive the equation relevant to super-Hubble modes of quantum fields in near-de Sitter spacetimes and derive two implications. We show the evolution of the diagonal density-matrix elements quickly approaches the Fokker-Planck equation of Starobinsky's stochastic inflationary picture. This provides an alternative first-principles derivation of this picture's stochastic noise and drift, as well as its leading corrections. (An application computes the noise for systems with a sub-luminal sound speed.) We argue that the presence of interactions drives the off-diagonal density-matrix elements to zero in the field basis. This shows why the field basis is the `pointer basis' for the decoherence of primordial quantum fluctuations while they are outside the horizon, thus allowing them to re-enter as classical fluctuations, as assumed when analyzing CMB data. The decoherence process is efficient, occurring after several Hubble times even for interactions as weak as gravitational-strength. Crucially, the details of the interactions largely control only the decoherence time and not the nature of the final late-time stochastic state, much as interactions can control the equilibration time for thermal systems but are largely irrelevant to the properties of the resulting equilibrium state.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑