On the primordial origin of the smoothing excess in the $Planck$ temperature power spectrum in light of LSS data

Abstract: The {\em Planck} DR3 measurements of the temperature and polarization anisotropies power spectra of the cosmic microwave background (CMB) show an excess of smoothing of the acoustic peaks with respect to $\Lambda$CDM, often quantified by a phenomenological parameter $A_{\rm L}$. A specific feature superimposed to the primordial power spectrum has been suggested as a physical solution for this smoothing excess. Here, we investigate the impact of this specific localized oscillation with a frequency linear in the wavenumber, designed to mimic the smoothing of CMB temperature spectrum corresponding to $A_{\rm L} \simeq 1.1-1.2$ on the matter power spectrum. We verify the goodness of the predictions in perturbation theory at next-to-leading order with a set of N-body simulations, a necessary step to study the non-linear damping of these primordial oscillations. We show that for a large portion of the parameter space, the amplitude of this primordial oscillation can be strongly damped on the observed nonlinear matter power spectrum at $z=0$, but a larger signal is still persistent at $z \lesssim 2$ and is therefore a target for future galaxy surveys at high redshifts. From an analysis of the BOSS DR12 two-point correlation function, we find ${\cal A}_{\rm lin} < 0.26$ at 95\% CL by keeping the frequency fixed to the best-fit of {\em Planck} data.