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Supermassive black hole scalarization and effective field theory

Farid Thaalba1,*, Pedro G. S. Fernandes2,†, and Thomas P. Sotiriou1,3,‡

  • 1Nottingham Centre of Gravity and School of Mathematical Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
  • 2Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 12, 69120 Heidelberg, Germany
  • 3School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom

  • *Contact author: Farid.Thaalba@nottingham.ac.uk
  • †Contact author: fernandes@thphys.uni-heidelberg.de
  • ‡Contact author: Thomas.Sotiriou@nottingham.ac.uk
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Phys. Rev. D 113, 064005 – Published 2 March, 2026

DOI: https://doi.org/10.1103/vtfr-8zxq

Abstract

A model in which black hole scalarization occurs for supermassive black holes, while their less massive counterparts remain nonscalarized, has been recently proposed. We explore whether this model can emerge in a variety of settings. First, we consider an effective field theory obtained by integrating out a heavy second scalar field. We show that the resulting effective field theory does not have the right coupling sign or the right hierarchy of scales. We then consider whether supermassive black hole scalarization could occur in theories with two (possibly light) scalars, and find that although they can violate black hole uniqueness through curvature- and spin-induced scalarization, they do not naturally produce scalarization exclusively for supermassive black holes. Finally, we assess whether a Higgs-type mechanism could enable supermassive black hole scalarization, and identify regions of parameter space where this is indeed possible.

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Phys. Rev. D 113, 064005– Published 2 March, 2026
  • Received 7 July 2025
  • Accepted 5 February 2026
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