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arXiv · 2305.12549

Higher-Derivative Quantum Gravity with Purely Virtual Particles: Renormalizability and Unitarity

Marco Piva
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Abstract

We review the formulation of quantum field theories with purely virtual particles, a new type of degrees of freedom that can mediate interactions without ever appear as external on-shell states. This property allows to solve the problem of ghosts in higher-derivative quantum gravity, leading to a renormalizable and unitary theory. The main steps for the BRST quantization of gravity are recalled and renormalizability is discussed. Then, we introduce purely virtual particles in a general quantum field theory and show the derivation of the so-called spectral identities, which are a key ingredient to prove unitarity. Finally, phenomenological consequences and predictions in inflationary cosmology are presented.

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Marco Piva. 2023-05-21. Higher-Derivative Quantum Gravity with Purely Virtual Particles: Renormalizability and Unitarity. https://arxiv.org/abs/2305.12549

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