RT Journal Article T1 Invisible dilaton A1 Brax, Philippe A1 Burrage, Clare A1 Ruiz Cembranos, José Alberto A1 Valageas, Patrick AB We analyze the dynamics of a light scalar field responsible for the mu term of the Higgs potential and coupled to matter via the Higgs-portal mechanism. We find that this dilaton model is stable under radiative corrections induced by the standard model particle masses. When the background value of the scalar field is stabilized at the minimum of the scalar potential, the scalar field fluctuations only couple quadratically to the massive fields of the standard model preventing the scalar direct decay into standard model particles. Cosmologically and prior to the electroweak symmetry breaking, the scalar field rolls down along its effective potential before eventually oscillating and settling down at the electroweak minimum. These oscillations can be at the origin of dark matter due to the initial misalignment of the scalar field compared to the electroweak minimum, and we find that, when the mass of the scalar field is less than the electron volt scale and acts as a condensate behaving like dark matter on large scales, the scalar particles cannot thermalize with the standard model thermal bath. As matter couples in a composition-dependent manner to the oscillating scalar, this could lead to a violation of the equivalence principle aboard satellites such as the MICROSCOPE experiment and the next generation of tests of the equivalence principle. Local gravitational tests are evaded thanks to the weakness of the quadratic coupling in the dark matter halo, and we find that, around other sources, these dilaton models could be subject to a screening akin to the symmetron mechanism. PB American Physical Society SN 2470-0010 YR 2023 FD 2023-05-09 LK https://hdl.handle.net/20.500.14352/112013 UL https://hdl.handle.net/20.500.14352/112013 LA eng NO Brax, P., Burrage, C., Cembranos, J. A. R. & Valageas, P. (2023). Invisible dilaton. Physical Review D 107, 095015. NO COST Actions: Cosmic WISPers CA21106 and Cosmo Verse CA2136Grant ST/T000732/1 NO Ministerio de Ciencia e Innovación (España) NO Agencia Estatal deInvestigación (España) NO European Commission NO Science and Technology Facilities Council (UK) NO Agence Nationale de la Recherche (France) NO Universitè Paris-Saclay DS Docta Complutense RD 21 abr 2025