In a new paper, the Aarhus cosmology group uses their likelihood emulator CLiENT to show that combining dark radiation–matter decoupling (DRMD) in Hot NEDE with self-interacting neutrinos offers a promising way to accommodate the ACT and SPT data while addressing the Hubble tension.

Interestingly, this provides an alternative to introducing running and running of the running of the primordial power spectrum (see https://arxiv.org/abs/2604.26541).

The combined model achieves a significantly better fit than either extension on its own, illustrating how different new-physics mechanisms can work together to address tensions in cosmological data.

The paper by Magnus Uggerhøj, Tobias Johannessen, Jeppe Pagaard Thybo, Steen Hannestad, and Thomas Tram is now on arXive: https://arxiv.org/abs/2611.13756