New Integrable Lattice Models From Fuss-Catalan Algebras

We construct new trigonometric solutions of the Yang-Baxter equation, using the Fuss-Catalan algebras, a set of multi-colored versions of the Temperley-Lieb algebra, recently introduced by Bisch and Jones. These lead to new two-dimensional integrable lattice models, describing dense gases of colored loops.Comment: 30 pages, 23 eps figures, uses harvmac.tex, epsf.te

Consensus report on 25 years of searches for damped Lyα\alpha galaxies in emission: Confirming their metallicity-luminosity relation at z≳2z \gtrsim 2

Starting from a summary of detection statistics of our recent X-shooter campaign, we review the major surveys, both space and ground based, for emission counterparts of high-redshift damped Ly$\alpha$ absorbers (DLAs) carried out since the first detection 25 years ago. We show that the detection rates of all surveys are precisely reproduced by a simple model in which the metallicity and luminosity of the galaxy associated to the DLA follow a relation of the form, ${\rm M_{UV}} = -5 \times \left(\,[{\rm M/H}] + 0.3\, \right) - 20.8$, and the DLA cross-section follows a relation of the form $\sigma_{DLA} \propto L^{0.8}$. Specifically, our spectroscopic campaign consists of 11 DLAs preselected based on their equivalent width of SiII $\lambda1526$ to have a metallicity higher than [Si/H] > -1. The targets have been observed with the X-shooter spectrograph at the Very Large Telescope to search for emission lines around the quasars. We observe a high detection rate of 64% (7/11), significantly higher than the typical $\sim$10% for random, HI-selected DLA samples. We use the aforementioned model, to simulate the results of our survey together with a range of previous surveys: spectral stacking, direct imaging (using the `double DLA' technique), long-slit spectroscopy, and integral field spectroscopy. Based on our model results, we are able to reconcile all results. Some tension is observed between model and data when looking at predictions of Ly$\alpha$ emission for individual targets. However, the object to object variations are most likely a result of the significant scatter in the underlying scaling relations as well as uncertainties in the amount of dust which affects the emission.Comment: 25 pages (7 of which in appendix), accepted for publication in MNRA

Two generalizations of the PRV conjecture

Let G be a complex connected reductive group. The PRV conjecture, which was proved independently by S. Kumar and O. Mathieu in 1989, gives explicit irreducible submodules of the tensor product of two irreducible G-modules. This paper has three aims. First, we simplify the proof of the PRV conjecture, then we generalize it to other branching problems. Finally, we find other irreducible components of the tensor product of two irreducible G-modules that appear for "the same reason" as the PRV ones

Les stratégies des organisations publiques pour éviter l'accès à l'information

Les lois sur l'accès à l'information contraignent les gouvernements et les administrations publiques à la transparence et ainsi à divulguer l'information dont ils disposent. Pourtant, si ces lois ont permis d'accroître l'information des citoyens, on constate que de nombreuses organisations publiques cherchent toujours à dissimuler de l'information alors qu'aucun intérêt public ou privé prépondérant ne justifie ce comportement. Cet article établit une typologie de ces comportements, les décrit et les illustre au travers de nombreux exemples

Access to information in Switzerland : From secrecy to transparency

Access to information legislations are now present in over 50 countries world-wide. Lagging behind some of its own Cantons, the Swiss Federal government was until recently one of the few hold outs in Europe. But, in December 2004, the Confederation voted the 'Loi sur la Transparence de l'administration' or Law on Transparency (LTrans) a Law that came into effect in July 2006. This paper presents an overview of the new Law and underlines the main institutional challenges to its introduction in Switzerland

Transparence et accès à l'information : typologie des comportements organisationnels des administrations publiques visant à limiter l'accès à l'information

La transparence de l'action gouvernementale et des administrations publiques est devenue une exigence démocratique inscrite dans de nombreux pays dans des lois sur l'accès à l'information. Or, si ces lois ont permis d'accroître l'information des citoyens, on constate toujours que de nombreuses organisations publiques cherchent à dissimuler de l'information alors qu'aucun intérêt public ou privé prépondérant ne justifie ce comportement. Ce working paper établit une typologie de ces comportements et les décrit avec notamment de nombreux exemples tirés des expériences faites aux USA, au Canada et en Suisse

Le Tactilo : au coeur du débat sur la régulation des jeux de hasard et d'argent

Dans plusieurs pays (Suisse, France, États-Unis, Royaume-Uni), le cadre de régulation des jeux de hasard et d'argent est différencié selon la nature et la forme des jeux. Ainsi, le système suisse est régulé différemment suivant qu'il s'agit de loteries et de paris ou de casinos. Dans chacun de ces deux cas, un cadre juridique et de régulation diffèrent s'applique. Le système devient complexe lorsque certains jeux ou opérations ne peuvent pas être clairement attribués à un système de régulation ou à un autre ou lorsque des conflits de compétence interviennent entre les autorités de régulation. C'est le cas du Tactilo. Ce working paper présente de manière synthétique les différents aspects de la régulation de ce nouveau mode de distribution des jeux que sont les automates de type Tactilo et discute les développements légaux et les implications financières entourant ce débat. Ces éléments permettent de comprendre le débat actuel et de mieux comprendre les enjeux de la décision attendue du Tribunal fédéral dans ce dossier. Le Tactilo, un jeu de loterie ou un jeu de casino...

Coexistence of Superconductivity and Spin Density Wave orderings in the organic superconductor (TMTSF)_2PF_6

The phase diagram of the organic superconductor (TMTSF)_2PF_6 has been revisited using transport measurements with an improved control of the applied pressure. We have found a 0.8 kbar wide pressure domain below the critical point (9.43 kbar, 1.2 K) for the stabilisation of the superconducting ground state featuring a coexistence regime between spin density wave (SDW) and superconductivity (SC). The inhomogeneous character of the said pressure domain is supported by the analysis of the resistivity between T_SDW and T_SC and the superconducting critical current. The onset temperature T_SC is practically constant (1.20+-0.01 K) in this region where only the SC/SDW domain proportion below T_SC is increasing under pressure. An homogeneous superconducting state is recovered above the critical pressure with T_SC falling at increasing pressure. We propose a model comparing the free energy of a phase exhibiting a segregation between SDW and SC domains and the free energy of homogeneous phases which explains fairly well our experimental findings.Comment: 13 pages, 10 figures, revised v: fig.9 added, section 4.2 rewritten, accepted v: sections 4&5 improve