Slow-roll inflation is a successful paradigm. However we find that even a small coupling of the inflaton to other light fields can dramatically alter the dynamics and predictions of inflation.As an example, the inflaton can generically have an axion-like coupling to gauge bosons. Even relatively small couplings will automatically induce a thermal bath during inflation. The thermal friction from this bath can easily be stronger than Hubble friction, significantly altering the usual predictions of any particular inflaton potential. Thermal effects suppress the tensor-to-scalar ratio r significantly, and predict unique non-gaussianities. This axion-like coupling provides a minimal model of warm inflation which avoids the usual problem of thermal backreaction on the inflaton potential. As a specific example, we find that hybrid inflation with this axion-like coupling can easily fit the current cosmological data. *

The phenomenological early dark energy (EDE) provides a promising solution to the Hubble tension in the form of an extra beyond-ΛCDM component that acts like a cosmological constant at early times (z ≥ 3000) and then dilutes away as radiation or faster. We show that a rolling axion coupled to a non-Abelian gauge group, which we call the 'dissipative axion' (DA), mimics this phenomenological EDE at the background level and presents a particle-physics model solution to the Hubble tension, while also eliminating fine-tuning in the choice of scalar-field potential. We compare the DA model to the EDE fluid approximation at the background level and comment on their similarities and differences. We determine that CMB observables sensitive only to the background evolution of the Universe are expected to be similar in the two models, strengthening the case for exploring the perturbations of the DA as well as for this model to provide a viable solution to the Hubble tension.1 The IR potential from the confining group is rapidly suppressed at temperatures above the confining scale and we have checked that its contribution is sub-dominant for our parameters.

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Brillouin spectroscopy allows non-contact, direct readout of viscoelastic properties of a material and has been a useful tool in material characterization1, structural monitoring2 and environmental sensing3,4. In the past, Brillouin spectroscopy has usually employed scanning Fabry-Perot etalons to perform spectral analysis which require high illumination power and long acquisition times, which prevents using this technique in biomedical applications. Our newly developed spectrometer overcomes this challenge by employing two virtually imaged phased arrays (VIPAs) in a cross-axis configuration, which enables us to do sub-GHz resolution spectral analysis with sub-seconds acquisition time and illumination power within the safety limits of biological tissue application5. This improvement allows for multiple applications of Brillouin spectroscopy, which are now being broadly explored in biological research and clinical application6.