Strong coupling and bounds on the spin-2 mass in massive gravity

Area of Science:

• Theoretical Physics
• Gravitational Theories
• Particle Physics

Background:

• The de Rham-Gabadadze-Tolley (dRGT) theory describes a single massive spin-2 field.
• This theory generically possesses a cutoff scale significantly below the Planck scale.
• This low cutoff arises from higher-derivative self-interactions of extra modes in the massive spin-2 multiplet.

Purpose of the Study:

• To investigate the perturbative viability of the dRGT massive spin-2 theory.
• To derive bounds on the mass of the massive spin-2 field.
• To determine the conditions under which the theory can be considered a valid description of massive gravity.

Main Methods:

• Analysis of higher-derivative self-interactions in the dRGT theory.
• Calculation of the effective cutoff scale, considering environmental effects and the graviton mass.
• Derivation of mass bounds by imposing perturbativity down to millimeter scales.

Main Results:

• The effective cutoff of the dRGT theory is dependent on environmental parameters and the massive spin-2 field's mass.
• For the theory to be perturbative down to millimeter scales, the massive spin-2 field mass is constrained to be approximately ≳O(1) meV in the generic case.
• Weaker bounds are found in scenarios involving fine-tuning.

Conclusions:

• The dRGT theory of a single massive spin-2 field is best understood as a theory of nonlinear propagation on a fixed background.
• It does not serve as a general approximation to Einstein's theory of general relativity.
• The derived mass bounds highlight the limitations and specific applicability of massive graviton theories.