  We study the prospects for detecting neutrino masses from the galaxy angular
power spectrum in photometric redshift shells of the Dark Energy Survey (DES)
over a volume of 20 (Gpc/h)^3 combined with the Cosmic Microwave Background
(CMB) angular fluctuations expected to be measured from the Planck satellite.
We find that for a Lambda-CDM concordance model with 7 free parameters in
addition to a fiducial neutrino mass of M_nu = 0.24 eV, we recover from DES
&Planck the correct value with uncertainty of +- 0.12 eV (95 % CL), assuming
perfect knowledge of the galaxy biasing. If the fiducial total mass is close to
zero, then the upper limit is 0.11 eV (95 % CL). This upper limit from DES
&Planck is over 3 times tighter than using Planck alone, as DES breaks the
parameter degeneracies in a CMB-only analysis. The analysis utlilizes spherical
harmonics up to 300, averaged in bin of 10 to mimic the DES sky coverage. The
results are similar if we supplement DES bands (grizY) with the VISTA
Hemisphere Survey (VHS) near infrared band (JHK). The result is robust to
uncertainties in non-linear fluctuations and redshift distortions. However, the
result is sensitive to the assumed galaxy biasing schemes and it requires
accurate prior knowledge of the biasing. To summarize, if the total neutrino
mass in nature greater than 0.1eV, we should be able to detect it with DES
&Planck, a result with great importance to fundamental Physics.
