Gravitational wave production from preheating with trilinear interactions

Understand

We investigate the production of gravitational waves (GWs) during preheating with monomial/polynomial inflationary potentials, considering a trilinear coupling $\phi\chi^2$ between a daughter field $\chi$ and the inflaton $\phi$.

• For sufficiently large couplings, the trilinear interaction leads to an exponential production of $\chi$ particles, and as a result, a large stochastic GW background (SGWB) is generated throughout the process.
• We study the linear and non-linear dynamics of preheating with lattice simulations, following the production of GWs through all relevant stages.
• We find that large couplings lead to SGWBs with a large amplitude today, of the order of $h^2\Omega_{\rm GW}^{(0)} \simeq 5\cdot10^{-9}$.