  We present neutrino mass bounds using 900,000 luminous galaxies with
photometric redshifts measured from Sloan Digital Sky Survey III Data Release
Eight (SDSS DR8). The galaxies have photometric redshifts between $z = 0.45$
and $z = 0.65$, and cover 10,000 square degrees and thus probe a volume of
3$h^{-3}$Gpc$^3$, enabling tight constraints to be derived on the amount of
dark matter in the form of massive neutrinos. A new bound on the sum of
neutrino masses $\sum m_\nu < 0.26$ eV, at 95% confidence level (CL), is
obtained after combining our sample of galaxies, which we call "CMASS", with
WMAP 7 year Cosmic Microwave Background (CMB) data and the most recent
measurement of the Hubble parameter from the Hubble Space Telescope (HST). This
constraint is obtained with a conservative multipole range choice of $30 < \ell
< 200$ in order to minimize non-linearities, and a free bias parameter in each
of the four redshift bins. We study the impact of assuming this linear galaxy
bias model using mock catalogs, and find that this model causes a small ($\sim
1-1.5 \sigma$) bias in $\Omega_{\rm DM} h^2$. For this reason, we also quote
neutrino bounds based on a conservative galaxy bias model containing
additional, shot noise-like free parameters. In this conservative case, the
bounds are significantly weakened, e.g. $\sum m_\nu < 0.36$ eV (95% confidence
level) for WMAP+HST+CMASS ($\ell_{\rm max}=200$). We also study the dependence
of the neutrino bound on multipole range ($\ell_{\rm max}=150$ vs $\ell_{\rm
max}=200$) and on which combination of data sets is included as a prior. The
addition of supernova and/or Baryon Acoustic Oscillation data does not
significantly improve the neutrino mass bound once the HST prior is included.
[abridged]
