High Energy Physics

The range of possible masses of particle dark matter spans over many orders of magnitude. The extremes of the mass range -- so-called ''superheavy'' and ''ultralight'' dark matter candidates -- are increasingly attracting attention due to their novel phenomenology and new developments in production mechanisms. In this talk I will discuss the complementary nature of superheavy and ultralight dark matter, starting from the production during cosmic inflation, using examples from the string theory axiverse and from a QCD-like dark sector.

I'll discuss four-point functions of CFT operators with infinite scaling dimension, which arise ubiquitously in both holographic and non-holographic CFTs in general dimension, as well as in the flat space limit of rigid QFTs on AdS. The space of these correlators is poorly understood, due to both their computational complexity and inaccessibility through standard bootstrap techniques. To navigate these challenges, I'll introduce a rigorous framework for extracting well-defined ``maximally heavy observables,'' which are analogous to intrinsic quantities describing statistical systems in the thermodynamic limit. These observables are highly constrained by crossing symmetry and unitarity, and shed light on the emergence of bulk locality through dynamical phase transitions. I'll relate this framework to torus partition functions at large central charge, and work out illustrative examples in generalized free theories and the four-point function of maximal giant gravitons in planar $\mathcal{N}=4$ SYM.