Quantum Gravity Constraints from Unitarity and Analyticity

By B. Bellazzini, C. Cheung, Grant N. Remmen. 2015

133 citations recorded by the source corpus.

We derive rigorous bounds on corrections to Einstein gravity using unitarity and analyticity of graviton scattering amplitudes. In D≥4 spacetime dimensions, these consistency conditions mandate positive coefficients for certain quartic curvature operators. We systematically enumerate all such positivity bounds in D=4 and D=5 before extending to D≥6. Afterwards, we derive positivity bounds for supersymmetric operators and verify that all of our constraints are satisfied by weakly coupled string theories. Among quadratic curvature operators, we find that the Gauss-Bonnet term in D≥5 is inconsistent unless new degrees of freedom enter at the natural cutoff scale defined by the effective theory. Our bounds apply to perturbative ultraviolet completions of gravity.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/b06b6834b9aaee1c430b702deac050302b4483fc

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Citations in the corpus

Positive signs in massive gravity (2016, background): “Assuming the Froissart unitarity bound [15, 16], the forward amplitude grows sufficiently slowly with s that the boundary contribution at infinity vanishes [7, 12].”
New positivity bounds from full crossing symmetry (2020, background): “Recently, there has been a lot of interest in applying the positivity bounds in particle physics, gravitational theories and cosmology [17–39].”
Sharpening the weak gravity conjecture with dimensional reduction (2015, background): “Along these lines, attempts to derive bounds on the low-energy effective action of quantum gravity from analyticity and unitarity of scattering amplitudes are noteworthy [55, 56], but so far only partially successful: what they constrain are combinations of the mass and charge of particles in the th”
Softness and amplitudes’ positivity for spinning particles (2016, background): “[12, 16], most of the positivity bounds for massive spin-1 or spin-2 bosons have actually focused on the “eaten” scalar modes, i.”
UV complete me: positivity bounds for particles with spin (2017, background): “Remaining agnostic about the explicit form of a UV complete description of gravity, it is possible to derive constraints on gravitational EFTs by nevertheless demanding that such a UV completion should exist [5, 6].”