Infrared Screening of the Cosmological Constant
Abstract
The observed cosmological constant is set by the deepest infrared scale of the present universe rather than by the microscopic scales that contribute to the vacuum energy. We show that this emerges as the quantum fluctuations of the gravitational field are progressively taken into account. Considering the Einstein-Hilbert+R2 truncation of gravity, we find that in a wide region of the parameter space the theory develops instabilities that give rise to large amplitude quantum fluctuations which govern the renormalization group flow. Once the flow enters this region, it remains there all the way towards the infrared and progressively loses memory of its boundary conditions. The running cosmological constant Λk (k is the running scale) is driven towards the universal infrared scaling Λk∼ λIR k2, with λIR= 1/(2(π−2)). At the deepest infrared scale kIR∼ H0 (the current Hubble scale), the cosmological constant is then screened to its observed value ΛIR∼ H02.
Related
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BibTeX
@misc{branchina2026infrared,
title = {{Infrared Screening of the Cosmological Constant}},
author = {Vincenzo Branchina and Riccardo Gandolfo and Arcangelo Pernace},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.29979},
eprint = {2609.29979},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.29979},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - UNPB
TI - Infrared Screening of the Cosmological Constant
AU - Vincenzo Branchina
AU - Riccardo Gandolfo
AU - Arcangelo Pernace
PY - 2026
DA - 2026/09/30
PB - arXiv
DO - 10.48550/arxiv.2609.29979
UR - https://arxiv.org/abs/2609.29979
AB - The observed cosmological constant is set by the deepest infrared scale of the present universe rather than by the microscopic scales that contribute to the vacuum energy. We show that this emerges as the quantum fluctuations of the gravitational field are progressively taken into account. Considering the Einstein-Hilbert+R^2 truncation of gravity, we find that in a wide region of the parameter space the theory develops instabilities that give rise to large amplitude quantum fluctuations which govern the renormalization group flow. Once the flow enters this region, it remains there all the way towards the infrared and progressively loses memory of its boundary conditions. The running cosmological constant Λ_k (k is the running scale) is driven towards the universal infrared scaling Λ_k∼ λ__IR k^2, with λ__IR= 1/(2(π−2)). At the deepest infrared scale k__IR∼ H_0 (the current Hubble scale), the cosmological constant is then screened to its observed value Λ__IR∼ H_0^2.
ER -