Higher neutrino mass allowed if Cold Dark Matter and Dark Energy are coupled

Abstract

Cosmological limits on neutrino masses are softened, by more than a factor 2, if Cold Dark Matter (CDM) and Dark Energy (DE) are coupled. In turn, a neutrino mass yielding $\hat{I}{\text{c◯}}_{\hat{I}}½$ up to $\sim 0.20$ allows coupling levels ${\hat{I}}^2\simeq 0.15,$ or more, already easing the coincidence problem. The coupling, in fact, displaces both $P(k)$ and $C_l$ spectra in a fashion opposite to neutrino mass. Estimates are obtained through a Fisher--matrix technique.

22 pages, 9 figures. Added appendix and references, corrected typos. Version to appear in New Astronomy