2025/09/11 by Boyle, Latham, Turok, Neil, Vaibhav, Vatsalya
#FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #High Energy Physics - Phenomenology (hep-ph) #High Energy Physics - Theory (hep-th)
paper · doi:10.48550/arxiv.2509.09346
Coupling quantum field theory (QFT) - even free QFT - to gravity leads to well-known problems. In particular, the stress tensor Tμν (gravity's source) and its correlators typically diverge in the UV, creating a conflict between the wildly inhomogeneous spacetime we expect quantum mechanically and the weakly-curved, macroscopic spacetime we observe. Are there QFTs for which these divergences cancel? Here, for simplicity, we consider free quantum fields on a classical curved background. The aforementioned divergences are related to the running of the gravitational couplings. We calculate the corresponding beta functions, identifying a special class of QFTs with UV fixed points at which ⟨ Tμν⟩ and all its correlators ⟨ T… T⟩ are UV finite. An intriguing example is a theory like the Standard Model (including right-handed neutrinos) with 12 gauge fields, 3 generations of 16 Weyl fermions and 36 four-derivative (Fradkin-Tseytlin) scalars. In the infrared, this theory has a positive Newton's constant G and an arbitrarily small cosmological constant Λ.