  The existence of the Standard Model (SM) Higgs implies that a gravitational
wave (GW) background is generated by the decay products of the Higgs, soon
after the end of inflation. Theoretically, all Yukawa and $SU(2)_L$ gauge
couplings of the SM are imprinted as features in the GW spectrum. In practice,
the signal from the most strongly coupled species dominates, rendering
inaccesible the information on the other species. If detected, this background
could be used for measuring properties of high-energy particle physics,
including beyond the SM. To achieve this goal, new high frequency GW detection
technology is required, beyond that of currently planned detectors.
