Enhanced Stochastic Gravitational Waves signals from Wess-Zumino chiral superfield

In this work, we investigate the possibility that supersymmetric structures may leave observable imprints in the stochastic gravitational-wave (GW) background generated during the reheating era. To this end, we construct a phenomenological interaction vertex describing the coupling between a single inflaton and the D-term sectors of a pair of chiral and anti-chiral superfields. In contrast to the conventional Yukawa coupling between the inflaton and structureless matter fields, we find that the supersymmetry-preserving chiral multiplet structure leads to a substantial enhancement, by at least one order of magnitude, in the amplitude of the resulting GWs spectrum. Our results therefore suggest that the interplay between reheating-era stochastic GWs and supersymmetric phenomenology merits further exploration and development.

💡 Research Summary

The paper investigates whether supersymmetric (SUSY) structures can leave observable imprints in the stochastic gravitational‑wave (GW) background generated during the reheating era. The authors construct a phenomenological interaction vertex that couples a single inflaton field φ to the D‑term sector of a pair of chiral (Φ) and anti‑chiral (Φ†) superfields. Starting from the superspace expansion of the chiral superfield, they extract two cubic interaction terms: a φψψ vertex (where ψ is a Majorana fermion) and a φϕϕ vertex (where ϕ is a complex scalar). Both ψ and ϕ share the same on‑shell mass m, reflecting the chiral multiplet structure.

Using the path‑integral formalism, the authors derive the full set of Feynman rules, including the graviton‑Majorana fermion coupling hψψ. Two‑body decay rates for φ→ψψ and φ→ϕϕ are computed, yielding expressions proportional to κ²y_D²M³ with kinematic factors depending on the mass ratio y=m/M. The central novelty lies in the three‑body decay processes φ→ψψ + graviton and φ→ϕϕ + graviton, which generate the stochastic GW signal. The squared amplitudes are evaluated with two‑component spinor techniques, leading to compact analytic forms (Eqs. 3.1 and 3.2). These amplitudes depend non‑trivially on the graviton energy E_l and the energies of the final‑state particles, encapsulated in dimensionless variables x=E_l/M and α=√