Heavy-Lifting of Gauge Theories By Cosmic Inflation

TL;DR

This work argues that primordial non-Gaussianity can act as a cosmological collider to probe heavy gauge-Higgs sectors with masses around the inflationary scale $H$. By coupling gauge-Higgs dynamics to the inflaton within both a slow-roll EFT and a Goldstone EFT framework, it derives tree- and loop-level NG signatures for Higgs scalars and massive gauge bosons, including a heavy-lifting mechanism that elevates current-scale Higgs/gauge masses to $H$ during inflation and yields RG-predicted mass ratios. The analysis provides explicit estimates for NG amplitudes $F$ across tree-level diagrams (single, double, triple exchanges) and mass regimes, discussing naturalness and the role of cosmic variance in observability. The results indicate that with favorable couplings and EFT cutoffs, observable NG signals tying to high-energy gauge structures could be accessible, offering a novel probe of naturalness and UV physics in the early universe. The paper also outlines future routes, including UV completions, SUSY considerations, and refined NG templates to extract mass and spin information from data.

Abstract

Future measurements of primordial non-Gaussianity can reveal cosmologically produced particles with masses of order the inflationary Hubble scale and their interactions with the inflaton, giving us crucial insights into the structure of fundamental physics at extremely high energies. We study gauge-Higgs theories that may be accessible in this regime, carefully imposing the constraints of gauge symmetry and its (partial) Higgsing. We distinguish two types of Higgs mechanisms: (i) a standard one in which the Higgs scale is constant before and after inflation, where the particles observable in non-Gaussianities are far heavier than can be accessed by laboratory experiments, perhaps associated with gauge unification, and (ii) a "heavy-lifting" mechanism in which couplings to curvature can result in Higgs scales of order the Hubble scale during inflation while reducing to far lower scales in the current era, where they may now be accessible to collider and other laboratory experiments. In the heavy-lifting option, renormalization-group running of terrestrial measurements yield predictions for cosmological non-Gaussianities. If the heavy-lifted gauge theory suffers a hierarchy problem, such as does the Standard Model, confirming such predictions would demonstrate a striking violation of the Naturalness Principle. While observing gauge-Higgs sectors in non-Gaussianities will be challenging given the constraints of cosmic variance, we show that it may be possible with reasonable precision given favorable couplings to the inflationary dynamics.

Figures (12)

• Figure 1: From left to right: (a) Tree level exchange of neutral massive scalar (in red) between inflatons (in black); (b) Loop level exchange of charged massive fields (in blue) between inflatons (in black). The external lines are taken to end at the end of inflation, conformal time, $\eta\approx 0$.
• Figure 2: NG in single-field inflation
• Figure 3: From left to right: (a) Single Exchange Diagram, (b) Double Exchange Diagram, (c) Triple Exchange Diagram. Note that all these diagrams rely on mixing between the inflaton fluctuation and massive scalar in the (implicit) non-trivial background of rolling $\phi_0(t)$.
• Figure 4: From left to right: (a) "OPE" approximation of three point function in squeezed limit as a two point function. The $\phi_0$ background causing mixing is not explicitly shown, as in Fig. \ref{['fig:three-diagrams']}. (b) The same "OPE" approximation expressed an inflaton-$h$ three point function with one inflaton leg set to zero momentum to now explicitly represent the background $\phi_0$.
• Figure 5: Dimensionless three-point function $F_h^{\text{single}}$\ref{['Ffunction']} for different masses in Goldstone Effective description \ref{['singleheft']} with $\lambda_2=0.2;\lambda_h=0.5;\Lambda=8H$.