We present constraints on neutrino masses , the primordial fluctuation spectrum from inflation , and other parameters of the \Lambda CDM model , using the one-dimensional Ly \alpha -forest power spectrum measured by from the Baryon Oscillation Spectroscopic Survey ( BOSS ) of the Sloan Digital Sky Survey ( SDSS-III ) , complemented by Planck 2015 cosmic microwave background ( CMB ) data and other cosmological probes .
This paper improves on the previous analysis by by using a more powerful set of calibrating hydrodynamical simulations that reduces uncertainties associated with resolution and box size , by adopting a more flexible set of nuisance parameters for describing the evolution of the intergalactic medium , by including additional freedom to account for systematic uncertainties , and by using Planck 2015 constraints in place of Planck 2013 .

Fitting Ly \alpha data alone leads to cosmological parameters in excellent agreement with the values derived independently from CMB data , except for a weak tension on the scalar index n _ { s } .
Combining BOSS Ly \alpha with Planck CMB constrains the sum of neutrino masses to \sum m _ { \nu } < 0.12 eV ( 95 % C.L . )
including all identified systematic uncertainties , tighter than our previous limit ( 0.15 eV ) and more robust .
Adding Ly \alpha data to CMB data reduces the uncertainties on the optical depth to reionization \tau , through the correlation of \tau with \sigma _ { 8 } .
Similarly , correlations between cosmological parameters help in constraining the tensor-to-scalar ratio of primordial fluctuations r .
The tension on n _ { s } can be accommodated by allowing for a running { \mathrm { d } } n _ { s } / { \mathrm { d } } \ln k .
Allowing running as a free parameter in the fits does not change the limit on \sum m _ { \nu } .
We discuss possible interpretations of these results in the context of slow-roll inflation .