We constrain the spectrum of primordial curvature perturbations by using recent Cosmic Microwave Background ( CMB ) and Large Scale Structure ( LSS ) data .
Specifically , we consider CMB data from the COBE , Boomerang and Maxima experiments , the real space galaxy power spectrum from the IRAS PSCz survey , and the linear matter power spectrum inferred from Ly - \alpha forest spectra , where we for simplicity assume the absence of appreciable covariances .
We study the case of single field slow roll inflationary models , and we extract bounds on the scalar spectral index , n , the tensor to scalar ratio , r , and the running of the scalar spectral index , \partial _ { { ln } k } , for various combinations of the observational data .
We find that CMB data , when combined with data from Lyman - \alpha forest , place strong constraints on the inflationary parameters .
Specifically , we obtain n \approx 0.9 , r \raise 1.29 pt \hbox { $ < $ \kern - 7.5 pt \raise - 4.73 pt \hbox { $ \sim $ } } 0.3 and \partial _ { { ln } k } \approx 0 , indicating that big n , big r models ( often referred to as hybrid models ) are ruled out .