  In the context of three-flavor neutrino mixing, we present a thorough study
of the phenomenological constraints applicable to three observables sensitive
to absolute neutrino masses: The effective neutrino mass in Tritium beta decay
(m_beta); the effective Majorana neutrino mass in neutrinoless double beta
decay (m_2beta); and the sum of neutrino masses in cosmology (Sigma). We
discuss the correlations among these variables which arise from the combination
of all the available neutrino oscillation data, in both normal and inverse
neutrino mass hierarchy. We set upper limits on m_beta by combining updated
results from the Mainz and Troitsk experiments. We also consider the latest
results on m_2beta from the Heidelberg-Moscow experiment, both with and without
the lower bound claimed by such experiment. We derive upper limits on Sigma
from an updated combination of data from the Wilkinson Microwave Anisotropy
Probe (WMAP) satellite and the 2 degrees Fields (2dF) Galaxy Redshifts Survey,
with and without Lyman-alpha forest data from the Sloan Digital Sky Survey
(SDSS), in models with a non-zero running of the spectral index of primordial
inflationary perturbations. The results are discussed in terms of
two-dimensional projections of the globally allowed region in the
(m_beta,m_2beta,Sigma) parameter space, which neatly show the relative impact
of each data set. In particular, the (in)compatibility between Sigma and
m_2beta constraints is highlighted for various combinations of data. We also
briefly discuss how future neutrino data (both oscillatory and non-oscillatory)
can further probe the currently allowed regions.
