2024/03/19 by Sergio L. Cacciatori, Cacciatori, Sergio L., Henri Epstein +3 · 3 citations
Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #FOS: Physical sciences #High Energy Physics - Theory (hep-th) #Quantum Chromodynamics and Particle Interactions
paper · pdf · doi:10.48550/arxiv.2403.13145
openalex publication_date 2024/03/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We discuss general one and two-loops banana diagrams with arbitrary masses on the de Sitter spacetime by using direct methods of dS quantum field theory in the dimensional regularization approach. In the one-loop case we also compute the effective potential for an O(N) model in d=4 dimension as an explicit function of the cosmological constant Λ, both exactly and perturbatively up to order Λ. For the two-loop case we show that the calculation is made easy thanks to a remarkable Kallen-Lehmann formula that has been in the literature for a while. We discuss the divergent cases at d=3 using a contiguity formula for generalized hypergeometric functions and we extract the dominant term at d=4 proving a general formula to deal with a divergent hypergeometric series.