QCD and strongly coupled gauge theories: challenges and perspectives

Abstract

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.

The hidden-charm pentaquark and tetraquark states

“…Interested readers may also consult reviews in Refs. [40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,39].…”

Quark-anti-quark potential in N $$ \mathcal{N} $$ = 4 SYM

“…[31] (see also e.g. [32][33][34] for some details of the QCD calculations of the quark-antiquark potential).…”

On the infrared behavior of the shear spectral function in hot Yang-Mills theory

“…Correcting for this was finally seen to exactly cancel the constant IR term from the unresummed spectral function, while leaving its earlier, correct UV behavior intact. 5 Having obtained both the unresummed and (partially) HTL resummed spectral functions, we proceeded to study their behavior as well as their effect on the imaginary time shear correlator. We observed that the resummation only affects the spectral function at very small ω, and that the deviation of our new imaginary time correlator from the one derived in [24] is in practice negligible.…”

“…[1][2][3][4][5]). Despite the strong experimental and phenomenological motivation, a nonperturbative first principles tool to predict its value is, however, still lacking, even though an extensive amount of work has been devoted to the topic in the weak coupling [6,7], lattice [8][9][10] and gauge/gravity frontiers [11][12][13].…”