Constraining primordial curvature perturbations with present and future GW detectors (2505.23521v1)

Abstract: Primordial scalar curvature perturbations ($\zeta$), typically probed on large cosmological scales via CMB and LSS observations, can be significantly enhanced on smaller scales by various early Universe mechanisms, for instance, non-minimal inflationary models. While decoupled at linear order, scalar and tensor perturbations, i.e., Gravitational Waves (GWs), interact at second order. As a consequence, an enhanced primordial scalar power spectrum $P_\zeta(k)$ can source a sizable stochastic GW background (SGWB). In these proceedings, we briefly review the generation mechanism of such signals, typically referred to as scalar-induced GWs (SIGWs), and discuss the prospects of measuring them with present and future Pulsar Timing Arrays datasets and future GW observatories like the Laser Interferometer Space Antenna LISA.