Massive Spin-2: Field-equations, Propagators, Massless-limit, and Perihelion Precessions
Th. A. Rijken, J. W. Wagenaar
TL;DR
The paper develops a massive spin-2 framework using an auxiliary-field (AF) formulation with an imaginary scalar ghost to achieve a smooth massless limit and circumvent the vDVZ discontinuity. Through Dirac constrained quantization and careful treatment of the auxiliary fields, it derives the spin-2 propagator and shows that, in the $b \to \infty$ limit, the theory yields a consistent massless spin-2 content while preserving correct Mercury perihelion precession. The analysis decomposes contributions from spin-2, scalar, and ghost sectors to the gravitational potential, showing that scalar-ghost cancellations restore Einsteinian predictions in the massless limit, and that finite-mass corrections are negligible within solar-system bounds. The work connects graviton mass effects to cosmological terms and provides a quantitative assessment against observational constraints, arguing that the imaginary ghost is essential for achieving the desired limits. Overall, it presents a coherent, quantized, AF-based approach to massive gravity with a physically viable massless limit and measurable—but currently tiny—deviations in planetary motion.
Abstract
This paper presents the quantization of massive and massless spin-2 particles, using the auxiliary field method. The issue, the so-called vDVZ-discontinuity, whether the perihelion precessions for a massive graviton are in agreement with the data, is studied in the context of this spin-2 theory in tree-approximation. In the context of this setting, it is found, that a massive gravitation model with an imaginary scalar ghost, for a small graviton mass is compatible with the perihelion-precession of Mercury, etc..
