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.
Highlights
Cosmic Inflation, originally invoked to help explain the homogeneity and flatness of the universe on large scales, provides an attractive framework for understanding inhomogeneities on smaller scales, such as the spectrum of temperature fluctuations in the Cosmic Microwave Background (CMB) radiation
Cosmological Collider Physics builds on the distinctive non-analytic momentum dependence of primordial NG mediated by particles with masses m ∼ H, in contrast to the analytic dependence of NG due purely to the inflationary dynamics, driven by fields with multiple light (m H)
We focused on the question of whether gauge-theories with such ultra-high ∼ H mass scales could be detected by this means, since such theories are obviously very highly motivated
Summary
Cosmic Inflation (see [1] for a review), originally invoked to help explain the homogeneity and flatness of the universe on large scales, provides an attractive framework for understanding inhomogeneities on smaller scales, such as the spectrum of temperature fluctuations in the Cosmic Microwave Background (CMB) radiation. In this way such a nonminimal coupling can lift up a gauge theory with a relatively low Higgs scale today, which we can access via collider or other probes, to the window of opportunity of cosmological collider physics during the inflationary era We will call this the “heavy-lifting” mechanism. We consider the more agnostic approach in which the dynamics of inflation itself is parametrized as a given background process [45], but in which the interactions of the gauge-Higgs sector and inflaton fluctuations are explicitly described This will allow for larger NG signals, capable in principle of allowing even multiple particles to be discerned. We will refer explicitly to H in the text throughout, again for ease of reading, and in the unnumbered equations within the text
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