## Should we laugh?

02/09/2008

Today on arxiv another paper by Oliveira and Silva is appeared (see here). These authors are well-known in the community for being the only one to have seen the gluon propagator bending toward zero in four dimensions being completely at odds with the rest of lattice computations (see here). They used asymmetric lattices. On their papers you will see just a single point in the computed propagator that bends. But maybe, the most shocking one is their paper where exponents of Yang-Mills theory are computed (see here). Here the results are even more striking: They are compatible with a scenario completely at odds with the rest of lattice computations on huge lattices. We would like to remember here that huge lattices arrived at $(27fm)^4$ (see here) and now there is no more interest to increase volumes. So, we have here two researchers, just two, that have such a serious evidence against the evidence! Should we laugh?

I think that the paper they presented today is absolutely unique. They show that there are differences in the SU(2) and SU(3) gluon propagators so that the latter goes to zero and the former does not! This means that the gluon propagator should depend on the gauge group. We just note that the scenario these authors describe is not perfectly coincident with the one emerging from truncation of Dyson-Schwinger equations but is similar to. Indeed, people working with Dyson-Scwinger equations do not see any of such a dependence. This should have given a serious hint at these authors that their conclusions are not correct.

This is the moment to understand. The scenario is set by lattice computations and this is plain evidence to use to trace a boundary between right and wrong. We need good ideas to lead us and not prejudices.

Update: My colleague Terry Goldman at LANL pointed me out that I was too hard in this post against the work of Oliveira and Silva. I have appreciated Terry’s criticism and so I apologize to whoever felt bad by this post.