Massive neutrinos and interacting dark matter look alike through the lens of lensing
arXiv:2511.01048 · doi:10.1103/r89c-jtp2
Abstract
We demonstrate that the suppression in the lensing power spectrum of the cosmic microwave background (CMB) caused by massive neutrinos can be mimicked by dark matter-baryon interactions at the precision of next-generation CMB experiments. Thus, a determination of neutrino masses from the CMB lensing power spectrum may be compromised. We illustrate the degeneracy for a dark matter-proton cross section , which arises in the -channel exchange of an ultralight mediator in the nonrelativistic limit.
7 pages, 7 figures, 1 table. Version to appear in PRD