TH Cosmo Coffee

The Axidental Universe

by Matthew Kleban (New York University)

Europe/Zurich
4-2-037 - TH meeting room (CERN)

4-2-037 - TH meeting room

CERN

20
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Description

I will describe a novel technique that renders theories of N axion fields analytically and numerically tractable. The number of meta-stable minima scales exponentially with N, making large N theories extremely complex “landscapes”.  For N~100s and with Planckian or GUT/string energy scales one generically finds some minima with vacuum energy consistent with dark energy, as well as many with larger and smaller (more negative) values. These minima are long-lived, and decay via thin-wall Coleman de Luccia transitions only to ~N neighbors. This landscape supports a variety of types of slow-roll inflation, and tunneling can be followed by inflation of roughly quadratic type, with density perturbations ~10^{-5}.  It also naturally contains one or more light fields that can solve the strong CP problem and serve as fuzzy or QCD axion dark matter. The minimal anthropic requirement that structure forms singles out cosmological histories that tunnel and then undergo ~60 efolds of inflation post-tunneling.  Hence, a theory of ~100s axions without model building and with only GUT-scale random parameters produces large universes with histories very much like our own, including a big bang (tunneling), slow-roll inflation, dark matter, and dark energy.

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