Abstract
We study complex saddles of the Lorentzian path integral for 4D axion gravity and its dual description in terms of a 3-form flux, which include the Giddings-Strominger Euclidean wormhole. Transition amplitudes are computed using the Lorentzian path integral and with the help of Picard-Lefschetz theory. The number and nature of saddles is shown to qualitatively change in the presence of a bilocal operator that could arise, for example, as a result of considering higher-topology transitions. We also analyze the stability of the Giddings-Strominger wormhole in the 3-form picture, where we find that it represents a perturbatively stable Euclidean saddle of the gravitational path integral. This calls into question the ultimate fate of such solutions in an ultraviolet-complete theory of quantum gravity.
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Loges, G.J., Shiu, G. & Sudhir, N. Complex saddles and Euclidean wormholes in the Lorentzian path integral. J. High Energ. Phys. 2022, 64 (2022). https://doi.org/10.1007/JHEP08(2022)064
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DOI: https://doi.org/10.1007/JHEP08(2022)064