[PAST EVENT] Physics Colloquium - Alexander Austregesilo
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- Open to the public
Alexander Austregesilo, Carnegie Mellon University, Title of Talk: Understanding the Strong Interaction through Hadron Spectroscopy
The strong interaction is the least understood of the four fundamental forces in nature, even though it is responsible for 99% of the mass of the visible universe as it binds the light quarks into hadrons like protons and neutrons. In recent years, advances in the theoretical description of the strong interaction and new methods for extracting the hadron spectrum from numerical simulations have greatly revived the interest in hadron spectroscopy. In addition, new experiments started to deliver high-precision data, often revealing unexpected signatures for states beyond the constituent quark model. As part of a global effort, the GlueX experiment at Jefferson Lab aims to study the light meson spectrum with an emphasis on the search for light hybrid mesons. Its unique selling point is a linearly-polarized 9 GeV photon beam that impinges on a liquid-hydrogen target contained within a hermetic detector with near-complete neutral- and charged-particle coverage. The experiment completed its first phase of data taking in 2018, and the quantity and precision of the data already exceed previous experiments for polarized photoproduction in this energy regime by orders of magnitude. A selection of early results is presented, focusing on the phenomenology of the production process with polarized photons. The potential to make significant contributions to the field of light-meson spectroscopy is demonstrated highlighting prominent examples. With significant upgrades to the detector, the upcoming second phase of GlueX will advance the exploration of the light meson spectrum with rare processes and final states with strange-quark content.