Monday, 18 April 2016

Building a website for physics courses with Drupal

I have been involved in building a new website for the theoretical physics courses at IPhT, using the content management framework Drupal. This post is the story of this experience, written for researchers who are considering embarking in similar projects.

Riccardo Guida and I have been organizing the IPhT courses for years (many years in Riccardo's case), and one year ago we finally decided to escape the IPhT website and set up a dedicated website for the courses. The problem with the IPhT website was that it did not know what a course was. A course was a collection of various objects: a number of "seminars", a "publication" where lecture notes could be stored, a few lines in a list of courses on a static webpage, etc. These objects did not talk to one another, and the same information had to be copy-pasted several times.

Tuesday, 12 April 2016

The light asymptotic limit of $W$ algebra conformal blocks

\(W\) algebras are natural extensions of the Virasoro algebra, the symmetry algebra of local conformal field theories in two dimensions. Conformal field theories with \(W\) algebra symmetry include \(W\) minimal models and conformal Toda theories, which are generalizations of Virasoro minimal models and Liouville theory respectively. In particular, \(sl_N\) conformal Toda theory is based on the \(W_N\) algebra, which has \(N-1\) generators with spins \(2,3,\dots, N\), and reduces to the Virasoro algebra in the case \(N=2\).

The problem of solving conformal Toda theory


Solving \(sl_{N\geq 3}\) conformal Toda theory is an outstanding problem. One may think that this is due to the complexity of the \(W_N\) algebra, with its quadratic commutators. I would argue that this is rather due to the complexity of the fusion ring of \(W_{N}\) representations, with its infinite fusion multiplicities. Due to these fusion multiplicities, solving \(sl_N\) conformal Toda theory does not boil down to computing three-point function of primary fields: rather, one should also compute three-point functions of infinitely many descendent fields.

Saturday, 2 April 2016

Perverse bibliometrics: the case of patents

Bibliometrics, the counting of publications and citations, is being used for evaluating researchers, research institutions, and academic journals. But simple bibliometric indicators can be gamed, and complex indicators lack transparency. No known indicator avoids these two problems, while some indicators (such as the journal impact factor) manage to have both. As a result, the misuse of bibliometrics has been widely denounced.

In spite of these problems with bibliometrics, someone had the idea to do bibliometrics with patents, in order to rank research institutions. The result is Reuters' list of the world's most innovative research institutions, which is topped by the Alternative Energies and Atomic Energy Commission (CEA). The methodology for establishing the list is not known in detail, but we do know that it is involves 10 different criterions, and is mainly based on the numbers of patents and citations thereof.