Quantum M^2 -> 2Lambda/3 discontinuity for massive gravity with a Lambda term

TL;DR

This paper investigates the classical and quantum discontinuities in massive gravity theories with a cosmological constant, revealing a new discontinuity at the partially massless limit due to degrees of freedom change.

Contribution

It demonstrates a classical continuity but quantum discontinuity at the partially massless limit in massive gravity with a Lambda term, extending previous findings on the van Dam-Veltman-Zakharov discontinuity.

Findings

Discontinuity reappears at one loop for M^2 -> 0 due to degrees of freedom change.

A similar discontinuity occurs at M^2 -> 2Lambda/3, involving a change in degrees of freedom.

Classical theory remains continuous, but quantum effects introduce a discontinuity.

Abstract

In a previous paper we showed that the absence of the van Dam-Veltman-Zakharov discontinuity as M^2 -> 0 for massive spin-2 with a Lambda term is an artifact of the tree approximation, and that the discontinuity reappears at one loop, as a result of going from five degrees of freedom to two. In this paper we show that a similar classical continuity but quantum discontinuity arises in the "partially massless" limit M^2 -> 2Lambda/3, as a result of going from five degrees of freedom to four.