QCD and strongly coupled gauge theories : challenges and perspectives

We highlight the progress, current status, and open challenges of QCD-driven physics, in theory and in experiment. We discuss how the strong interaction is intimately connected to a broad sweep of physical problems, in settings ranging from astrophysics and cosmology to strongly coupled, complex systems in particle and condensed-matter physics, as well as to searches for physics beyond the Standard Model. We also discuss how success in describing the strong interaction impacts other fields, and, in turn, how such subjects can impact studies of the strong interaction. In the course of the work we offer a perspective on the many research streams which flow into and out of QCD, as well as a vision for future developments.Peer reviewe

What happens to the Υ \Upsilon and η b in the quark-gluon plasma? Bottomonium spectral functions from lattice QCD

We study bottomonium spectral functions in the quark-gluon plasma in the Υ and η b channels, using lattice QCD simulations with two flavours of light quark on highly anisotropic lattices. The bottom quark is treated with nonr elativistic QCD (NRQCD). In the temperature range we consider, 0 . 42 ≤ T/T c ≤ 2 . 09, we find that the ground states survive, whereas the excited states are suppressed as the te mperature is increased. The position and width of the ground states are compared to analy tical effective field theory (EFT) predictions. Systematic uncertainties of the maximu m entropy method (MEM), used to construct the spectral functions, are discussed in s ome detail