Title: Fractals, Strings, and Particle Collisions

Abstract:

A guided walk through the landscape of proton collisions at the LHC. I will highlight some striking "emergent" properties of the strong nuclear force, which despite their ubiquitous nature remain poorly understood. The most obvious and spectacular of these are the vortex lines in QCD which are thought to enforce confinement of quarks and gluons inside hadrons. In the context of high-energy physics, phenomenological models of "string fragmentation" have been the successful dominant paradigm since the eighties; nonetheless, the wealth of data from the LHC is now challenging some of the fundamental assumptions and approximations these models rely on.

I will discuss what we are seeing in the LHC data, and where that may be leading us. A second class of phenomena which only reveal their true splendour at infinite perturbative order are the fractal-like structures of quark and gluon bremsstrahlung patterns in QCD. I will discuss some recent progress on understanding and modelling these patterns in new ways, which is being turned into a new full-fledged dynamical model of hadron collisions, VINCIA.