Supersymmetric Hidden Sector Phase Transitions Could Produce Detectable Gravitational Waves
A new theoretical study finds that supercooled first-order phase transitions in a supersymmetric hidden sector could produce gravitational wave signals detectable by next-generation observatories, the Einstein Telescope and Cosmic Explorer. The mechanism relies on a radiatively generated potential barrier along a D-flat direction, with the signal strength governed by the gaugino-to-vacuum-expectation-value ratio and a portal coupling between hidden and visible sectors. If confirmed, this would provide a rare observational window into supersymmetric physics and dark matter dynamics in the early universe.
Researchers have modeled supercooled first-order phase transitions occurring in a supersymmetric hidden sector featuring a spontaneously broken U(1)_X symmetry, targeting the frequency sensitivity range of the Einstein Telescope and Cosmic Explorer. Because the tree-level quartic coupling vanishes along the D-flat direction, the potential barrier is generated radiatively through soft supersymmetry-breaking mass splittings, with the gaugino mass setting barrier depth and the soft scalar mass stabilizing the broken vacuum. For gaugino-to-vacuum-expectation-value ratios between roughly 0.05 and 0.23, the predicted gravitational wave energy density reaches approximately 3×10⁻¹⁰ near the percolation boundary. The signal amplitude depends sensitively on a portal coupling between the hidden and visible sectors: a cold hidden sector produces signals rising from the Einstein Telescope detection floor at portal coupling 10⁻⁶, while a hotter initial hidden sector yields large signals even for weak coupling. The authors tracked this evolution using an 11-variable Boltzmann system distinguishing the cold nucleating exterior from the reheated true-vacuum interior. Additionally, the same hidden sector framework can account for the observed dark matter relic density through relativistic dark-quark freeze-out followed by entropy dilution from hidden-Higgs decay, with dark quark masses in the 30–800 keV range and negligible impact on the effective number of relativistic species.
What's missing
The study is a theoretical preprint and has not yet undergone peer review. Key open questions include whether the assumed soft SUSY-breaking parameter ranges are consistent with existing collider or cosmological constraints. The paper does not address detectability timelines for the Einstein Telescope or Cosmic Explorer, nor does it discuss degeneracies with other gravitational wave sources in the same frequency band.
What different sources said
- arXiv astro-phCenter
Natural Supercooling and Reheating along Supersymmetric Flat Directions and Observable Gravitational Waves at the Einstein Telescope and the Cosmic Explorer
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