Unique gravitational wave signatures of GLPV scalar-tensor theories

Fuente: arXiv
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Main Authors: Domènech, Guillem, Ganz, Alexander, Gorji, Mohammad Ali, Yamaguchi, Masahide
Format: Preprint
Published: 2025
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author Domènech, Guillem
Ganz, Alexander
Gorji, Mohammad Ali
Yamaguchi, Masahide
author_facet Domènech, Guillem
Ganz, Alexander
Gorji, Mohammad Ali
Yamaguchi, Masahide
contents We study gravitational waves induced by scalar primordial fluctuations in Gleyzes-Langlois-Piazza-Vernizzi (GLPV), beyond Horndeski, scalar-tensor theories. We uncover, at the level of the action, a new scalar-scalar-tensor interaction, unique to GLPV models disconnected from Horndeski via disformal transformation. The new interaction, arising in the unitary-degenerate (U-DHOST) sector of GLPV, leads to third derivatives in the source for scalar-induced tensor modes, which are absent in Horndeski-related theories. Such new higher-derivative terms lead to a further enhanced production of induced gravitational waves. We predict that for a scale-invariant primordial spectrum, the induced gravitational wave spectral density has a characteristic frequency dependence proportional to $f^5$. Such a fast-rising spectrum offers a potential unique signature of modified gravity in the early universe.
format Preprint
id arxiv_https___arxiv_org_abs_2509_05027
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Unique gravitational wave signatures of GLPV scalar-tensor theories
Domènech, Guillem
Ganz, Alexander
Gorji, Mohammad Ali
Yamaguchi, Masahide
General Relativity and Quantum Cosmology
Cosmology and Nongalactic Astrophysics
High Energy Physics - Theory
We study gravitational waves induced by scalar primordial fluctuations in Gleyzes-Langlois-Piazza-Vernizzi (GLPV), beyond Horndeski, scalar-tensor theories. We uncover, at the level of the action, a new scalar-scalar-tensor interaction, unique to GLPV models disconnected from Horndeski via disformal transformation. The new interaction, arising in the unitary-degenerate (U-DHOST) sector of GLPV, leads to third derivatives in the source for scalar-induced tensor modes, which are absent in Horndeski-related theories. Such new higher-derivative terms lead to a further enhanced production of induced gravitational waves. We predict that for a scale-invariant primordial spectrum, the induced gravitational wave spectral density has a characteristic frequency dependence proportional to $f^5$. Such a fast-rising spectrum offers a potential unique signature of modified gravity in the early universe.
title Unique gravitational wave signatures of GLPV scalar-tensor theories
topic General Relativity and Quantum Cosmology
Cosmology and Nongalactic Astrophysics
High Energy Physics - Theory
url https://arxiv.org/abs/2509.05027