Perspectives on Wilson loops in strongly-coupled Yang-Mills theories
Strongly-coupled Yang-Mills theories encompass many of the most intriguing open problems in physics, including colour confinement, the internal structure of neutron stars, and a full comprehension of gauge/gravity duality. We continue the research programme, conducted over many decades, of exploring the physics of strongly coupled gauge theories, giving special attention to the use of Wilson loops as probes of the physics of gauge theories. We examine in particular a newly-recognised phase of Yang-Mills theories known as `partial confinement’. This is postulated to appear in the crossover region of the quark-gluon plasma and to take an important role in gauge/gravity duality. We present evidence that flux tubes form in the confined sector of the partially confined phase. This is the first direct evidence for any statement about the dynamics of the partially confined phase. We furthermore argue that the partially confined phase can be distinguished from the totally confined and deconfined phases with the use of global symmetries. This permits the first acknowledgement of the partially confined phase in SU(N) gauge groups of finite N, and offers more prospects for understanding the physics of any manifestation of the partially confined phase in quantum chromodynamics. Finally, we employ the AdS/CFT correspondence to examine renormalization group flows in strongly coupled gauge theories on spherical defects harbouring hypermultiplets of Dirac fermions and their scalar super partners. We find that these defects flow in the infrared to line operators that we determine to be Wilson and Wilson-‘t Hooft loops. We thus find a new UV completion of Wilson-‘t Hooft loops, simultaneously discovering an interesting example of cross-dimensional renormalisation group flows on defects. There is hope that our results can be adapted to allow experimental realisation in spherical graphene and fullerenes.
https://eprints.soton.ac.uk/482473/
https://eprints.soton.ac.uk/482473/1/Southampton_PhD_Thesis_corrections_PDFA3b.pdf