3 papers
hep-th2026
Analyticity and positivity of Green's functions without Lorentz
Paolo Creminelli, Alessandro Longo, Borna Salehian +1
We study the properties imposed by microcausality and positivity on the retarded two-point Green's function in a theory with spontaneous breaking of Lorentz invariance. We assume i…
hep-th2026
On the Asymptotic Causal Structure in Gravitational EFTs
Bruno Bucciotti, Paolo Creminelli, Alessandro Longo +2
It is usually assumed that a healthy EFT should not allow superluminal propagation. In the presence of gravity, however, the notion of superluminality becomes subtle, since there i…
gr-qc2024
To the Problem of Cosmic Expansion in Massive Gravity
Lavinia Heisenberg, Alessandro Longo, Giovanni Tambalo +1
We consider evolving, spatially flat isotropic and homogeneous (FLRW) cosmologies in ghost-free (dRGT) massive gravity. In this theory, no dynamical flat FLRW background exists if…