We present a new upper limit of \sum m _ { \nu } \leq 0.28 ( 95 \% CL ) on the sum of the neutrino masses assuming a flat \mathrm { \Lambda CDM } cosmology .
This relaxes slightly to \sum m _ { \nu } \leq 0.34 and \sum m _ { \nu } \leq 0.47 when quasi non-linear scales are removed and w \neq - 1 , respectively .
These bounds are derived from a new photometric redshift catalogue of over 700,000 Luminous Red Galaxies ( MegaZ DR7 ) with a volume of 3.3 ( Gpc h ^ { -1 } ) ^ { 3 } , extending over the redshift range 0.45 < z < 0.65 and up to angular scales of \ell _ { \mathrm { max } } = 300 .
The data are combined with WMAP 5-year CMB fluctuations , Baryon Acoustic Oscillations ( BAO ) , type 1a Supernovae ( SNe ) and an HST prior on the Hubble parameter .
This is the first combined constraint from a photometric redshift catalogue with other cosmological probes .
When combined with WMAP this data set proves to be as constraining as the addition of all SNe and BAO data available to date .
The upper limit is one of the tightest and ‘ cleanest ’ constraints on the neutrino mass from cosmology or particle physics .
Furthermore , if the aforementioned bounds hold , they all predict that current-to-next generation neutrino experiments , such as KATRIN , are unlikely to obtain a detection .