arXiv subjects

Francesco Ferrarin

Publications and source records attributed to Francesco Ferrarin.

3 recordsLinked to original sources

arXiv2026

Asymptotic safety is not generic

Asymptotically safe quantum gravity proposes a non-perturbative ultraviolet completion of gravity in which the high-energy behavior is controlled by an ultraviolet fixed point---the Reuter fixed point---for which there is robust evidence from a wide range of settings and truncations. The existence of asymptotic safety requires non-trivial zeros of beta functions, raising the question of how generic such fixed-point solutions are. In this work, we tackle this issue by investigating chiral perturbation theories. We focus on SU(2) and SU(3) chiral models, which share key features with gravity such as perturbative non-renormalizability or nonlinear interactions, but which are known to admit a different ultraviolet completion via new degrees of freedom. Using the functional renormalization group, we study these theories within a quartic-derivative truncation and find no evidence for an interacting fixed point. This result suggests that asymptotic safety is not generic, but rather a feature pertaining to certain special systems.

hep-th↗

arXiv2026

Worldsheet functional RG and the $α'$-tower

We apply the functional renormalization group to the worldsheet theory of the bosonic string. Imposing the Weyl anomaly cancellation as a condition on the local renormalization group flow, we derive flow equations for the background couplings and the corresponding effective spacetime equations of motion, first in a two-derivative truncation, on a general curved background. We then consider a truncation to all orders in $α'$, which captures only a subset of the possible tensor structures but is analytically tractable, in analogy with $f(R)$-like approximations. Within this truncation, we obtain Tseytlin's spacetime effective action, and we use it to study solutions to all orders in $α'$, including black holes. Our results show that the functional renormalization group can be implemented on the string worldsheet and provide a framework to access the strong-curvature regime. As a longer-term goal, this may allow one to test the scenario of effective asymptotic safety in string theory, in which an approximately scale-invariant regime lies between the low-energy effective field theory and a stringy completion.

hep-th↗

arXiv2026

Impact of quantum gravity on the UV sensitivity of extremal black holes

Recent work has revealed that extremal Kerr black holes may exhibit a sensitivity to higher-derivative corrections to Einstein's equations, displaying singularities in the tidal forces at the horizon. However, in a purely gravitational context, this "ultraviolet sensitivity" translates into a strong dependence on the Wilson coefficients in the low-energy effective field theory. These, in turn, are fixed by the underlying theory of quantum gravity in the ultraviolet. We find a prediction for these coefficients within the framework of asymptotically safe quantum gravity, and show that, if the quantum gravity scale is trans-Planckian, this horizon-scale ultraviolet sensitivity is avoided.

hep-th↗