Fingerprinting models of first-order phase transitions by the synergy between collider and gravitational-wave experiments

TL;DR

This work develops a Fisher-matrix framework to quantify how future space-based gravitational-wave detectors (LISA, DECIGO, BBO) can constrain both the spectral features and the underlying particle-physics parameters of models that induce first-order cosmological phase transitions. By modeling the GW spectrum from sound waves and turbulence and incorporating instrument noise and astrophysical foregrounds, the authors forecast constraints on transition parameters (α, β/H_*, T_*) and map these to parameters in three beyond-Standard-Model scenarios: O(N) singlet extensions with/without classical conformal invariance, a real Higgs singlet extension, and a classically conformal B-L model. They demonstrate that GW observations are highly complementary to collider probes, with DECIGO/BBO typically providing stronger parameter constraints and LISA contributing significant information, particularly for certain models and parameter regimes. The results underscore the potential of combined GW-collider programs to fingerprint and pinpoint the Higgs-sector structure and new physics responsible for early-Universe phase transitions. The study also highlights degeneracies and the importance of multi-spectrum information and foreground treatment in achieving robust model discrimination.

Abstract

We investigate the sensitivity of future space-based interferometers such as LISA and DECIGO to the parameters of new particle physics models which drive a first-order phase transition in the early Universe. We first perform a Fisher matrix analysis on the quantities characterizing the gravitational wave spectrum resulting from the phase transition, such as the peak frequency and amplitude. We next perform a Fisher analysis for the quantities which determine the properties of the phase transition, such as the latent heat and the time dependence of the bubble nucleation rate. Since these quantities are determined by the model parameters of the new physics, we can estimate the expected sensitivities to such parameters. We illustrate this point by taking three new physics models for example: (1) models with additional isospin singlet scalars (2) a model with an extra real Higgs singlet, and (3) a classically conformal $B-L$ model. We find that future gravitational wave observations play complementary roles to future collider experiments in pinning down the parameters of new physics models driving a first-order phase transition.

Figures (35)

• Figure 1: Sensitivity curves for LISA (green-solid), DECIGO (green-dashed) and BBO (green-dotted). Blue curves correspond to the GW spectra for the sample points 1-4 in the main text. Red lines show the contribution from compact white dwarf binaries $S_{\rm WD}$.
• Figure 2: $1~\sigma$ contours for Point 1 (left column) and 2 (right column) for LISA (top), DECIGO (middle) and BBO (bottom). Three contours in each panel correspond to $T_{\rm obs} = 1$, $3$ and $10$ years. The spectral slopes are taken to be $(n_L,n_R) = (3,-4)$.
• Figure 3: $1~\sigma$ contours for Point 3 (left column) and 4 (right column). Otherwise the same as Fig. \ref{['fig:FisherGeneral1']}.
• Figure 4: $1~\sigma$ fractional error $\Delta f_{\rm peak}/\hat{f}_{\rm peak}$ (left) and $\Delta \Omega_{\rm GW,peak}/\hat{\Omega}_{\rm GW,peak}$ (right) for the fiducial values $\hat{f}_{\rm peak}$ and $\hat{\Omega}_{\rm GW, peak}$ for LISA (top), DECIGO (middle) and BBO (bottom). The spectral slopes and observational period are taken to be $(n_L,n_R) = (3,-4)$ and $T_{\rm obs} = 1$ year.
• Figure 5: Sensitivity curves for LISA (green-solid), DECIGO (green-dashed) and BBO (green-dotted). Red line shows the foreground from compact white dwarf binaries $S_{\rm WD}$. Each panel corresponds to Point A--C in the main text from left to right.