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 \Omega _ { \nu } up to \sim 0.20 allows coupling levels \beta \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 .