Constraints on Single-Field Inflation from the BOSS Galaxy Survey

Nonlocal primordial non-Gaussianity (NLPNG) is a smoking gun of interactions in single-field inflationary models and can be written as a combination of the equilateral and orthogonal templates. We present the first constraints on these from the redshift-space galaxy power spectra and bispectra of the BOSS data. These are the first such measurements independent of the cosmic microwave background fluctuations. We perform a consistent analysis that includes all necessary nonlinear corrections generated by NLPNG and vary all relevant cosmological and nuisance parameters in a global fit to the data. Our conservative analysis yields joint limits on the amplitudes of the equilateral and orthogonal shapes, f(NL)(equil) = 940 +/- 600 and f(NL)(ortho) = -170 +/- 170 (both at 68% CL). These can be used to derive constraints on coefficients of the effective single-field inflationary Lagrangian; in particular, we find that the sound speed of inflaton fluctuations has the bound c(s) >= 0.013 at 95% CL. Fixing the quadratic galaxy bias and cosmological parameters, the constraints can be tightened to f(NL)(equil) = 260 +/- 300 and f(NL)(ortho) = -23 +/- 120 (68% CL).