DESY Colloquium: The Phenomenologist's Guide to the Axiverse

I was pleased to visit Hamburg and give the Particle and Astroparticle Physics Colloquium at DESY on March 3, 2026.

The abstract of the talk is reproduced below.

Axions offer a uniquely rich window into physics beyond the Standard Model, linking the solution of the strong CP problem to dark matter and to the broader “axiverse” predicted in many ultraviolet-complete theories.

In this talk, I trace axions across the vast range of masses and scales they may inhabit: from the ultralight sub-eV regime and the largest cosmological distances, where their interactions with the visible sector are purely gravitational and large-scale structure (LSS) surveys provide the primary probes; through the keV-MeV range, where hadronic interactions become relevant and, intriguingly, discovery may occur at nuclear fusion facilities; to the smallest distances and heavier GeV-TeV axions explored at next-generation lepton-ion colliders.

Addressing this extraordinary span of scales demands an equally broad phenomenological toolkit, from effective field theories of LSS to AI-assisted modeling of atomic nuclei. In this context, I reflect on how the exploration of the axiverse reshapes the role of modern phenomenology at the interface of particle, nuclear, and cosmological physics.

Related papers: Large-Scale Structure Probes of the Post-Inflationary Axiverse, Searching for exotic scalars at fusion reactors, and New Physics at the Muon (Synchrotron) Ion Collider.

The talk took place in the Auditorium (Bldg 5, DESY Hamburg) and was also available on Zoom. More details are available on the DESY colloquium page, and the slides are also available here.