Symmetry factor

The third day of the conference was really a half-day. The reason is that the organizers scheduled a conference hike in the beautifull Treman Park with subsequent barbeque. The day stared with experimentral talks on semileptonic and leptonic charm decays — here CLEO-c has a fantastic advantage of an experiment in pristine enviroment. This, of course, is partially off-set by huge statistics of other experiments. At the end of the first section Aida El-Khadra talked about lattice approaches to formfactors and decay constants. And yes, she did show that plot of HPQCD collaboration that they show for three years already. Some of their results are quite amazing and dwarf the experimental results (and also somewhat inconsistent with them). F. Follana elaborated on HPQCD collaboration’s results. Then there were several talks on semileptonic decays, including Richard Hill’s talk on z-expansion. The point is that one has no idea what q^2-dependence semileptonic form-factors have, so meaningful comaprision of theory and experiment is a bit unclear — that is, if you want to claim model-independent theory. He puts some meaning into how to do that.

 At the end, Peter Cooper reported on the number of doubly-charmed baryon production at SELEX. Now, it is known (for once, from the calculations  of my former postdoc A. Onishchenko) that the production cross-section that they measure is _orders_ of magnitude higher than what is predicted. Jon Rosner made an intersting suggestion that those states could even be highly-excited single charm states. The rest of the session was about charmed baryons and their decays. In particular, H.-Y. Cheng gave an extensive discussion of charmed baryon spectroscopy.  

The conference hike was probably ok, I didn’t go (I did it when I lived in Ithaca) — it’s hard to go up and down with a kid’s stroller. It also started to rain midway through the hike. In taht respect, giving out a “conference umbrella” instead of usual conference bag was entirely appropriate.