On-shell approach to scalar hair in spinning binaries

Abstract We propose an on-shell description of spinning binary systems in gravitational theories where compact objects display scalar hair. The framework involves matter particles of arbitrary spin which, in addition to the minimal coupling to gravitons, are conformally coupled to a massless scalar...

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Main Authors: Adam Falkowski, Panagiotis Marinellis
Format: Article
Language:English
Published: SpringerOpen 2025-05-01
Series:Journal of High Energy Physics
Subjects:
Online Access:https://doi.org/10.1007/JHEP05(2025)045
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author Adam Falkowski
Panagiotis Marinellis
author_facet Adam Falkowski
Panagiotis Marinellis
author_sort Adam Falkowski
collection DOAJ
description Abstract We propose an on-shell description of spinning binary systems in gravitational theories where compact objects display scalar hair. The framework involves matter particles of arbitrary spin which, in addition to the minimal coupling to gravitons, are conformally coupled to a massless scalar mediating non-standard interactions. We use the unitary factorization techniques to derive the on-shell amplitudes relevant for emission of scalars and gravitons in matter scattering, paying attention to parametrize the freedom due to contact terms. Using the KMOC formalism, these amplitudes allow one to derive succinct expressions for the radiation waveforms at the leading post-Minkowskian order, together with the associated memory effects. Furthermore, we compute the power emitted via gravitational and scalar radiation in hyperbolic encounters of compact objects. After a continuation to bound orbits, these are compared with results obtained in specific scalar-tensor theories where black holes exhibit scalar hair, such as the scalar-Gauss-Bonnet or dynamical Chern-Simons theories. Finally, we identify possible deformations from the conformal coupling that can contribute to radiation observables at the same post-Newtonian order.
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spelling doaj-art-e6570aacfafe4a52bb6298ad2761b94d2025-08-20T03:25:15ZengSpringerOpenJournal of High Energy Physics1029-84792025-05-012025514110.1007/JHEP05(2025)045On-shell approach to scalar hair in spinning binariesAdam Falkowski0Panagiotis Marinellis1Université Paris-Saclay, CNRS/IN2P3, IJCLabUniversité Paris-Saclay, CNRS/IN2P3, IJCLabAbstract We propose an on-shell description of spinning binary systems in gravitational theories where compact objects display scalar hair. The framework involves matter particles of arbitrary spin which, in addition to the minimal coupling to gravitons, are conformally coupled to a massless scalar mediating non-standard interactions. We use the unitary factorization techniques to derive the on-shell amplitudes relevant for emission of scalars and gravitons in matter scattering, paying attention to parametrize the freedom due to contact terms. Using the KMOC formalism, these amplitudes allow one to derive succinct expressions for the radiation waveforms at the leading post-Minkowskian order, together with the associated memory effects. Furthermore, we compute the power emitted via gravitational and scalar radiation in hyperbolic encounters of compact objects. After a continuation to bound orbits, these are compared with results obtained in specific scalar-tensor theories where black holes exhibit scalar hair, such as the scalar-Gauss-Bonnet or dynamical Chern-Simons theories. Finally, we identify possible deformations from the conformal coupling that can contribute to radiation observables at the same post-Newtonian order.https://doi.org/10.1007/JHEP05(2025)045Black HolesScattering Amplitudes
spellingShingle Adam Falkowski
Panagiotis Marinellis
On-shell approach to scalar hair in spinning binaries
Journal of High Energy Physics
Black Holes
Scattering Amplitudes
title On-shell approach to scalar hair in spinning binaries
title_full On-shell approach to scalar hair in spinning binaries
title_fullStr On-shell approach to scalar hair in spinning binaries
title_full_unstemmed On-shell approach to scalar hair in spinning binaries
title_short On-shell approach to scalar hair in spinning binaries
title_sort on shell approach to scalar hair in spinning binaries
topic Black Holes
Scattering Amplitudes
url https://doi.org/10.1007/JHEP05(2025)045
work_keys_str_mv AT adamfalkowski onshellapproachtoscalarhairinspinningbinaries
AT panagiotismarinellis onshellapproachtoscalarhairinspinningbinaries