J/{\psi} production in pp collisions and in Pb-Pb collisions at the LHC with the ALICE experiment

We report the recent measurements of the inclusive J/{\psi} production in pp collisions at \sqrt{s} = 2.76 TeV, in pp collisions at \sqrt{s} = 7 TeV and in Pb-Pb collisions at \sqrt{s_{NN}} = 2.76 TeV with the ALICE detector at the LHC. The J/{\psi} mesons are detected down to pT = 0 GeV/c via their di-muon decay channel at forward rapidity (2.5 < y < 4) and via their di-electron decay channel at mid-rapidity (|y| < 0.9). A special emphasis is put on the nuclear modification factor which is compared to the predictions of current J/{\psi} production models

Quarkonium measurements in Pb-Pb and p-Pb collisions with ALICE at the LHC

The ALICE experiment has measured quarkonium production in Pb-Pb collisions at \sqrt{sNN} = 2.76 TeV and in p-Pb collisions at \sqrt{sNN} = 5.02 TeV. The measurements are performed in the dielectron de- cay channel at mid-rapidity (|yLAB| < 0.9) and in the dimuon decay channel at forward rapidity (2.5 < yLAB < 4). We focus in particular on the J/{\psi} nuclear modification factor measured both in Pb-Pb and p- -Pb collisions and on the {\Upsilon}(1S) nuclear modification factor measured in Pb-Pb collisions

Finite dimensional comodules over the Hopf algebra of rooted trees

The aim of this paper is an algebraic study of the Hopf algebra H_R of rooted trees, which was introduced in \cite{Kreimer1,Connes,Broadhurst,Kreimer2}. We first construct comodules over H_R from finite families of primitive elements. Furthermore, we classify these comodules by restricting the possible families of primitive elements, and taking the quotient by the action of certain groups. In the next section, we give a formula about primitive elements of the subalgebra of ladders, and construct a projection operator on the space of primitive elements. It allows us to obtain a basis of the primitive elements by an inductive process, which answers one of the questions of \cite{Kreimer}. In the last sections, we classify the Hopf algebra endomorphisms and the coalgebras endomorphisms, using the graded Hopf algebra gr(H_R) associated to the filtration by deg_p of \cite{Kreimer}. We then prove that H_R is isomorphic to gr(H_R), and deduce a decomposition of the group of the Hopf algebra automorphisms of H_R as a semi-direct product.Comment: LaTeX, 26 page

Projective metrics and contraction principles for complex cones

In this article, we consider linearly convex complex cones in complex Banach spaces and we define a new projective metric on these cones. Compared to the hyperbolic gauge of Rugh, it has the advantage of being explicit, and easier to estimate. We prove that this metric also satisfies a contraction principle like Birkhoff's theorem for the Hilbert metric. We are thus able to improve existing results on spectral gaps for complex matrices. Finally, we compare the contraction principles for the hyperbolic gauge and our metric on particular cones, including complexification of Birkhoff cones. It appears that the contraction principles for our metric and the hyperbolic gauge occur simultaneously on these cones. However, we get better contraction rates with our metric.Comment: 21 pages, 4 figure

Bayesian analysis of hierarchical multi-fidelity codes

This paper deals with the Gaussian process based approximation of a code which can be run at different levels of accuracy. This method, which is a particular case of co-kriging, allows us to improve a surrogate model of a complex computer code using fast approximations of it. In particular, we focus on the case of a large number of code levels on the one hand and on a Bayesian approach when we have two levels on the other hand. The main results of this paper are a new approach to estimate the model parameters which provides a closed form expression for an important parameter of the model (the scale factor), a reduction of the numerical complexity by simplifying the covariance matrix inversion, and a new Bayesian modelling that gives an explicit representation of the joint distribution of the parameters and that is not computationally expensive. A thermodynamic example is used to illustrate the comparison between 2-level and 3-level co-kriging

Incorporating Insurance Provisions in Microfinance Contracts: Learning from Visa®?

microfinance, insurance, reputation