Radiative corrections to the R and R 2 invariants from torsion fluctuations on maximally symmetric spaces

Abstract We derive the runnings of the R and R 2 operators that stem from integrating out quantum torsion fluctuations on a maximally symmetric Euclidean background, while treating the metric as a classical field. Our analysis is performed in a manifestly covariant way, exploiting both the recently-...

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Main Authors: Riccardo Martini, Gregorio Paci, Dario Sauro
Format: Article
Language:English
Published: SpringerOpen 2024-12-01
Series:Journal of High Energy Physics
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Online Access:https://doi.org/10.1007/JHEP12(2024)138
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author Riccardo Martini
Gregorio Paci
Dario Sauro
author_facet Riccardo Martini
Gregorio Paci
Dario Sauro
author_sort Riccardo Martini
collection DOAJ
description Abstract We derive the runnings of the R and R 2 operators that stem from integrating out quantum torsion fluctuations on a maximally symmetric Euclidean background, while treating the metric as a classical field. Our analysis is performed in a manifestly covariant way, exploiting both the recently-introduced spin-parity decomposition of torsion perturbations and the heat kernel technique. The Lagrangian we start with is the most general one for 1-loop computations on maximally symmetric backgrounds involving kinetic terms and couplings to the scalar curvature that is compatible with a gauge-like symmetry for the torsion. The latter removes the twice-longitudinal vector mode from the spectrum, and it yields operators of maximum rank four. We also examine the conditions required to avoid ghost instabilities and ensure the validity of our assumption to neglect metric quantum fluctuations, demonstrating the compatibility between these two assumptions. Then, we use our findings in the context of Starobinsky’s inflation to calculate the contributions from the torsion tensor to the β-function of the R 2 term. While this result is quantitatively reliable only at the 0-th order in the slow-roll parameters or during the very early stages of inflation — due to the background choice — it qualitatively illustrates how to incorporate quantum effects of torsion in the path integral formalism.
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spelling doaj-art-6edbd3c7e0be4f7cb71eff06429924a82025-01-05T12:07:03ZengSpringerOpenJournal of High Energy Physics1029-84792024-12-0120241214810.1007/JHEP12(2024)138Radiative corrections to the R and R 2 invariants from torsion fluctuations on maximally symmetric spacesRiccardo Martini0Gregorio Paci1Dario Sauro2INFN — Sezione di PisaINFN — Sezione di PisaINFN — Sezione di PisaAbstract We derive the runnings of the R and R 2 operators that stem from integrating out quantum torsion fluctuations on a maximally symmetric Euclidean background, while treating the metric as a classical field. Our analysis is performed in a manifestly covariant way, exploiting both the recently-introduced spin-parity decomposition of torsion perturbations and the heat kernel technique. The Lagrangian we start with is the most general one for 1-loop computations on maximally symmetric backgrounds involving kinetic terms and couplings to the scalar curvature that is compatible with a gauge-like symmetry for the torsion. The latter removes the twice-longitudinal vector mode from the spectrum, and it yields operators of maximum rank four. We also examine the conditions required to avoid ghost instabilities and ensure the validity of our assumption to neglect metric quantum fluctuations, demonstrating the compatibility between these two assumptions. Then, we use our findings in the context of Starobinsky’s inflation to calculate the contributions from the torsion tensor to the β-function of the R 2 term. While this result is quantitatively reliable only at the 0-th order in the slow-roll parameters or during the very early stages of inflation — due to the background choice — it qualitatively illustrates how to incorporate quantum effects of torsion in the path integral formalism.https://doi.org/10.1007/JHEP12(2024)138Renormalization and RegularizationModels of Quantum GravityCosmological models
spellingShingle Riccardo Martini
Gregorio Paci
Dario Sauro
Radiative corrections to the R and R 2 invariants from torsion fluctuations on maximally symmetric spaces
Journal of High Energy Physics
Renormalization and Regularization
Models of Quantum Gravity
Cosmological models
title Radiative corrections to the R and R 2 invariants from torsion fluctuations on maximally symmetric spaces
title_full Radiative corrections to the R and R 2 invariants from torsion fluctuations on maximally symmetric spaces
title_fullStr Radiative corrections to the R and R 2 invariants from torsion fluctuations on maximally symmetric spaces
title_full_unstemmed Radiative corrections to the R and R 2 invariants from torsion fluctuations on maximally symmetric spaces
title_short Radiative corrections to the R and R 2 invariants from torsion fluctuations on maximally symmetric spaces
title_sort radiative corrections to the r and r 2 invariants from torsion fluctuations on maximally symmetric spaces
topic Renormalization and Regularization
Models of Quantum Gravity
Cosmological models
url https://doi.org/10.1007/JHEP12(2024)138
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AT gregoriopaci radiativecorrectionstotherandr2invariantsfromtorsionfluctuationsonmaximallysymmetricspaces
AT dariosauro radiativecorrectionstotherandr2invariantsfromtorsionfluctuationsonmaximallysymmetricspaces