Saturday, August 18, 2007

Lattice 2007 -- Day Six

My apologies for the delay in posting this. A cold and various personal matters kept me from posting it earlier.

The first plenary talk today was Walter Wilcox speaking about deflation methods for fermion inverters. Deflation methods like GMRES-DR are based on Krylov subspace ideas, where the Krylov space is augmented by some (approximate) eigenvectors to remove the corresponding eigenvalues from the system, thus improving convergence.

Next was Falk Bruckmann, who spoke about exploring the QCD vacuum with lattice QCD. The nonperturbative degrees off freedom relevant for the QCD vacuum are topological objects (vortices, monopoles and instantons). Studying these on the lattice is hard, but progress is being made.

The third talk of the session, about renormalization-group flows in multi-parameter in φ4 theories, was given by Ettore Vicari. Critical phenomena can be described in terms of a few critical exponent; one way to determine these is by looking at fixed points of renormalisation group flows. Since there are only a certain number of universality classes into which those critical points can fall, one can study these by looking at φ4 models falling into different classes (Landau-Ginzburg-Wilson models); this may even have some applications to determining the nature of the QCD phase transition.

After the coffee break, Michele Della Morte got a plenary session of his own for his talk about determining heavy quark masses. A number of determinations of heavy-quakr observables were summarised, and a more detailed overview of recent progress in determining the b-quark mass using HQET was given.

After that, the organisers thanked the staff who had made the conference possible, and they received a round of well-deserved applause. The organisers got some equally well-deserved applause of their own, and all partcipants were invited to attend Lattice 2008 in Williamsburg, VA, which will be held July 14-19, 2008. Looking forward beyond next year, Lattice 2009 was announced to take place in Beijing, and so the meeting adjourned.

Finally I had some time to look around the city properly, and so I visited the Johannes Kepler-Gedächtnishaus (Kepler's dying place, and today a museum about his life) with some colleagues. After that, highlights on our tour round the city were the romanesque Schottenkirche (the church of a monastery build in the 11th century by Iro-Scottish monks) and St. Emmeram (the church of a former monastery that now serves as the palace of the Princess of Thurn and Taxis). I will do some more sightseeing tomorrow morning, but since I don't think it will interest my readers too much, this closes my coverage of Lattice 2007.