Enhanced Stochastic Gravitational Waves signals from Wess-Zumino chiral superfield

Abstract

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.

Figures (10)

• Figure 1: The upper panel illustrates the two-body decay of the inflaton into a pair of Majorana fermions, mediated by the two interaction vertices $\mathcal{V}_{(\varphi\psi\psi)}^{(q_{1},q_{2},\widetilde{\mathrm{I}}_{1,\downarrow},\dot{\widetilde{\mathrm{I}}}_{2,\downarrow})}$ and $\mathcal{V}_{(\varphi\psi\psi)}^{(q_{1},q_{2},\dot{\widetilde{\mathrm{I}}}_{1,\uparrow},\widetilde{\mathrm{I}}_{2,\uparrow})}$, presented in Appendix. \ref{['CubicInflaMajorana']} and Fig. \ref{['FigPsiI1PsiI2Inflatonpsipsi']}, respectively. Correspondingly, the lower panel, together with Figs. \ref{['ThreeBodyMajoranaCase1Case2']}–\ref{['ThreeBodyMajoranaCase3Case4']}, depicts the full three-body decay process in which the inflaton decays into a pair of Majorana fermions accompanied by the emission of a single graviton.
• Figure 2: This figure, together with Fig. \ref{['ThreeBodyMajoranaCase3Case4']} and the lower panel of Fig. \ref{['RefTwoThreeBodyMixMajorana']}, collectively illustrates the full three-body decay process in which the inflaton decays into a pair of Majorana fermions accompanied by the emission of a single graviton.
• Figure 3: This figure, together with Fig. \ref{['ThreeBodyMajoranaCase1Case2']} and the lower panel of Fig. \ref{['RefTwoThreeBodyMixMajorana']}, collectively illustrates the complete three-body decay process in which the inflaton decays into a pair of Majorana fermions accompanied by the emission of a single graviton.
• Figure 4: The upper panel illustrates the two-body decay of the inflaton into a pair of scalar particles, mediated by the interaction vertex $\mathcal{V}_{(\varphi\phi\phi)}^{(q_{1},q_{2})}$ given in \ref{['ThreePointScalarPairFinal']}. Correspondingly, the lower panel depicts the complete three-body decay process in which the inflaton decays into a scalar pair accompanied by the emission of a single graviton.
• Figure 5: In the upper panel, the shaded regions indicate the parameter space in the $\lambda$–$x$ plane where $f_{\mathcal{M}}^{\text{(majorana)}}(y,\lambda,x)>0$ for fixed $y=0.01, 0.1$ situations. The red dashed and purple dashed curves denote the constraint lines $\lambda_{\min}(x)=E_{p,\min}(x)/M$ and $\lambda_{\max}(x)=E_{p,\max}(x)/M$ (given by Eq. \ref{['ThreeBodyEpmax']}–\ref{['ThreeBodyEpmin']}), respectively. Note that, according to the differential three-body decay formula Eq. \ref{['GenericThreeBodyDifferentialDecay']}, the physically relevant parameter region is given by the intersection of the shaded area with domain bounded by $\lambda_{\min}(x)$ and $\lambda_{\max}(x)$. Similarly to the upper panel, the lower panel presents the corresponding result for the case of scalar final-state particles.