Anthropic predictions for vacuum energy and neutrino masses

Abstract

It is argued that the observed vacuum energy density and the small values of the neutrinomasses could be due to anthropic selection effects. Until now, these two quantities havebeen treated separately from each other and, in particular, anthropic predictions for thevacuum energy were made under the assumption of zero neutrino masses. Here weconsider two cases. In the first, we calculate predictions for the vacuum energy for afixed (generally nonzero) value of the neutrino mass. In the second we allow bothquantities to vary from one part of the Universe to another. We find that theanthropic predictions for the vacuum energy density are in a better agreementwith observations when one allows for nonzero neutrino masses. We also findthat the individual distributions for vacuum energy and the neutrino massesare reasonably robust and do not change drastically when one adds the othervariable.