On the length expectation values in quantum Regge calculus

TL;DR

This paper explores a generalized quantum Regge calculus framework where edge lengths are ambiguously defined, and demonstrates how quantization can lead to either zero or nonzero length expectations, indicating a transition to a continuous theory.

Contribution

It introduces a new superspace extension for quantum Regge calculus with ambiguous edge lengths and shows how quantization depends on a parameter, affecting the continuum limit.

Findings

Quantum measure can be uniquely fixed in the extended superspace.

Quantization parameter determines whether length expectations are zero or nonzero.

Zero length expectation values imply a dynamically emerging continuous spacetime.

Abstract

Regge calculus configuration superspace can be embedded into a more general superspace where the length of any edge is defined ambiguously depending on the 4-tetrahedron containing the edge. Moreover, the latter superspace can be extended further so that even edge lengths in each the 4-tetrahedron are not defined, only area tensors of the 2-faces in it are. We make use of our previous result concerning quantisation of the area tensor Regge calculus which gives finite expectation values for areas. Also our result is used showing that quantum measure in the Regge calculus can be uniquely fixed once we know quantum measure on (the space of the functionals on) the superspace of the theory with ambiguously defined edge lengths. We find that in this framework quantisation of the usual Regge calculus is defined up to a parameter. The theory may possess nonzero (of the order of Plank scale) or zero length expectation values depending on whether this parameter is larger or smaller than a certain value. Vanishing length expectation values means that the theory is becoming continuous, here {\it dynamically} in the originally discrete framework.