Primordial Gravitational Waves from Scalar Backreaction in Axion-SU(2) Inflation

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Autori principali: Cielo, Mattia, Dimastrogiovanni, Ema, Fasiello, Matteo, Papageorgiou, Alexandros
Natura: Preprint
Pubblicazione: 2026
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author Cielo, Mattia
Dimastrogiovanni, Ema
Fasiello, Matteo
Papageorgiou, Alexandros
author_facet Cielo, Mattia
Dimastrogiovanni, Ema
Fasiello, Matteo
Papageorgiou, Alexandros
contents In this work, we perform the first numerical study of strong scalar backreaction in spectator chromo-natural inflation (SCNI) in the case where the spectator sector decays during inflation. The tachyonic instability in scalar fluctuations, activated as the system crosses the $m_Q = \sqrt{2}$ threshold, amplifies perturbations and may significantly alter the background dynamics. The strong scalar backreaction regime introduces an effective quartic term in the potential for the gauge field background that rapidly drives it to zero, accelerating the axion-gauge system decay. We describe the dynamics of such decay and derive the gravitational wave spectrum for a set of benchmark parameters. Interestingly, the signal may peak at interferometer scales and lie within LISA's projected sensitivity.
format Preprint
id arxiv_https___arxiv_org_abs_2601_08622
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Primordial Gravitational Waves from Scalar Backreaction in Axion-SU(2) Inflation
Cielo, Mattia
Dimastrogiovanni, Ema
Fasiello, Matteo
Papageorgiou, Alexandros
Cosmology and Nongalactic Astrophysics
High Energy Physics - Phenomenology
In this work, we perform the first numerical study of strong scalar backreaction in spectator chromo-natural inflation (SCNI) in the case where the spectator sector decays during inflation. The tachyonic instability in scalar fluctuations, activated as the system crosses the $m_Q = \sqrt{2}$ threshold, amplifies perturbations and may significantly alter the background dynamics. The strong scalar backreaction regime introduces an effective quartic term in the potential for the gauge field background that rapidly drives it to zero, accelerating the axion-gauge system decay. We describe the dynamics of such decay and derive the gravitational wave spectrum for a set of benchmark parameters. Interestingly, the signal may peak at interferometer scales and lie within LISA's projected sensitivity.
title Primordial Gravitational Waves from Scalar Backreaction in Axion-SU(2) Inflation
topic Cosmology and Nongalactic Astrophysics
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2601.08622