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  • Open Access

Hidden Sector Custodial Naturalness

Thede de Boer1,*, Manfred Lindner1,†, and Andreas Trautner2,‡

  • *Contact author: thede.deboer@mpi-hd.mpg.de
  • †Contact author: lindner@mpi-hd.mpg.de
  • ‡Contact author: trautner@cftp.ist.utl.pt
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Phys. Rev. Lett. 137, 031801 – Published 14 July, 2026

DOI: https://doi.org/10.1103/g4wr-5vfy

Abstract

Custodial naturalness is a recently introduced idea that combines conformal and scalar sector custodial symmetry to address the electroweak (EW) scale hierarchy problem of the standard model (SM). We introduce a new model that realizes custodial naturalness without extension of the SM gauge group. The number of new dynamical degrees of freedom is minimized, and the custodial symmetry is reduced to SO(5). This requires a new scalar singlet field that automatically is a good dark matter (DM) candidate, produced via freeze-in with moderate couplings. The most minimal scenario allows the quantum critical generation of the EW scale in a phenomenologically viable way requiring a UV completion at around 1011  GeV. Including ingredients for neutrino mass generation can push this scale to MPl.

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Outline

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Phys. Rev. Lett. 137, 031801– Published 14 July, 2026
  • Received 9 August 2025
  • Accepted 25 June 2026
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