Background Independent Quantum Field Theory and Gravitating Vacuum Fluctuations

Understand

The scale dependent effective average action for quantum gravity complies with the fundamental principle of Background Independence.

• Ultimately the background metric it formally depends on is selected self-consistently by means of a suitable generalization of Einstein's equation.
• Self-consistent backround spacetimes are scale dependent, and therefore "going on-shell" at the points along a given renormalization group (RG) trajectory requires understanding two types of scale dependencies: the (familiar) direct one carried by the off-shell action functional, and an indirect one related to the self-consistent background geometry.
• This paper is devoted to a careful delineation and analysis of certain general questions concerning the indirect scale dependence, as well as a detailed explicit investigation of the case where the self-consistent metrics are determined predominantly by the RG running of the cosmological constant.