SMEFT Effects on the Gravitational Wave Spectrum from an Electroweak Phase Transition

Future gravitational wave observations are potentially sensitive to new physics corrections to the Higgs potential once the first-order electroweak phase transition arises. We study the Standard Model effective field theory (SMEFT) dimension-six operator effects on the Higgs potential, where three types of effects are taken into account: (i) SMEFT tree level effect on phi 6 operator, (ii) SMEFT tree level effect on the wave function renormalization of the Higgs field, and (iii) SMEFT top-quark one-loop level effect. The sensitivity of future gravitational wave observations to these effects is numerically calculated by performing a Fisher matrix analysis. We find that the future gravitational wave observations can be sensitive to (ii) and (iii) once the first-order electroweak phase transition arises from (i). The dimension -eight phi 8 operator effects on the first-order electroweak phase transition are also discussed. The sensitivities of the future gravitational wave observations are also compared with those of future collider experiments.