workshop schedule

Workshop on Nonperturbative Aspects of Gauge Fields and Strings: JENA 2000

Twenty-seven years after the inception of QCD its low-energy features are still not fully understood. The two main problems are the spontaneous breakdown of chiral symmetry and confinement. While the former is reasonably well described by the instanton vacuum, the property of confinement remains somewhat elusive. Nonetheless, the last few years have seen some remarkable progress in this direction. With the work of Seiberg and Witten there is now an exact non-perturbative solution of a strongly coupled gauge theory in four dimensions, though in a supersymmetric setting. This work has leant new support to the old idea of describing the vacuum as a dual superconductor where confinement is due to monopole condensation and a dual Meissner effect. In addition, lattice calculations using (variants of) 't Hooft's maximal abelian gauge fixing find that abelian and monopole fields are the dominant configurations in the path integral (abelian and monopole dominance). It is, however, difficult to confirm these results in a gauge independent way. Depending on the gauge chosen, there are alternative confinement mechanisms (like e.g. vortex percolation). In addition, the relation to the instanton vacuum remains to be further investigated.

Without simplifying assumptions like supersymmetry, it is rather difficult to confirm the lattice results analytically. Already on the kinematical level one has to deal with the issues of gauge fixing ambiguities, the Gribov problem and the like. A theoretical description of the confinement dynamics starting from first principles at present seems rather hopeless. Thus, for the time being, one has to rely on the respectable tradition of model building and effective field theories. One particular candidate of these, the dual Abelian Higgs model, has recently been shown to lead to an effective 4d string theory of confinement.

Remarkably, also from the pure string theory side there is now a route towards confinement via the celebrated AdS/CFT correspondence. Using effective supergravity models one can study the large-N sector of gauge theories, in particular Wilson loops, glueballs and even the shape of the flux tube. More recently, it was observed that string vacua with a nonvanishing B-field induce a noncommutative deformation of the spacetime structure underlying effective Yang-Mills theories on branes.

It thus seems that, after a long period of divergence, gauge field and string theory are again converging towards each other.

Topics to be Covered

The workshop will bring together experts working on the following aspects of these problems:

Before the beginning of the workshop coffee will be provided at the cafeteria of the theory building ("Abbeanum").

Session I: Thursday, February 10th, Lecture Hall 2, Abbeanum, Fröbelstieg 1

14:00 - 14:10   Opening
14:10 - 15:00Asorey Monopoles, Gauge Fixing and Confinement
15:00 - 15:50Müller-PreusskerLattice Gauge Theories with Boundary Conditions
15:50 - 16:10   Coffee Break
16:10 - 17:00Bruckmann Instantons and Monopoles in Abelian Projections
17:00 - 17:50Reinhardt Magnetic Vortices in Yang-Mills Theory
17:50 - 18:10  Coffee Break
18:10 - 19:00Pepe Nature and Properties of Center Vortices

Session II: Friday, February 11th, Lecture Hall 2, Abbeanum, Fröbelstieg 1

09:00 - 09:50Langfeld Realization of Confinement in Novel Gauges
09:50 - 10:40Heinzl Instantons and Gribov Copies in the Maximally Abelian Gauge
10:40 - 11:00   Coffee Break
11:00 - 11:50Thies On the Phase Structure of the 't Hooft Model
11:50 - 12:40Stamatescu On the Topological Structure of the Yang-Mills Vacuum - Problems and Results of Lattice Simulations
12:40 - 14:00  Lunch Break

Session III: Friday, February 11th, Lecture Hall 2, Abbeanum, Fröbelstieg 1

14:00 - 14:50Zakharov Power Corrections from Short Distances in QCD
14:50 - 15:40WeissQCD Instantons and Zero Modes in Hard Scattering Processes
15:40 - 16:00   Coffee Break
16:00 - 16:50Polonyi Renormalization of Periodic Potentials
16:50 - 17:40Smilga Normalized Vacuum States in Supersymmetric Matrix Models with any Gauge Group
17:40 - 18:00  Coffee Break
18:00 - 18:50Ketov Exact Multi-Monopole Moduli Space Metrics from Superspace

For Friday evening, 8:00 p.m., we will reserve a few tables at some downtown restaurant.

Session IV: Saturday, February 12th, Lecture Hall 2, Abbeanum, Fröbelstieg 1

09:00 - 09:45Brandhuber The Coulomb Branch of Gauge Theories in the AdS/CFT Correspondence
09:45 - 10:30Sachs Field Theory and Non-BPS States in String Theory
10:30 - 10:50   Coffee Break
10:50 - 11:35Mansfield AdS/CFT and the Schrödinger Functional
11:35 - 12:20Theisen Field Theory Anomalies from the AdS/CFT Correspondence
12:20 - 12:40  Coffee Break/Snacks
12:40 - 13:25Strobl Introduction to Poisson Sigma Models
13:25 - 14:10Klimcik Poisson Sigma Models and Manin Pairs