We report on our recent evaluation of the s-channel cut contribution to J/ψ hadroproduction. We show that it is likely significantly larger than the usual cut contribution of the colour-singlet model (CSM), which is known to underestimate the experimental measurements. Here the s-channel cut develops for configurations with off-shell quarks in the bound state. A correct treatment of its contribution requires the introduction of a fourpoint function, partially constrained by gauge invariance and limiting behaviours at small and large momenta. When the unconstrained degrees of freedom are fixed to reproduce the Tevatron data, we show that RHIC data are remarkably well reproduced down to very low transverse momenta P T without need of resummation of initial-state gluon effects. This unique feature might be typical of s-channel cut contribution.

Abstract. Using standard group theoretical techniques we construct the exact wave function of the [70, 1 − ] multiplet in the orbital, spin and flavor space. This symmetric wave function is compared to that customarily used in the 1/N c expansion, which is asymmetric. The comparison is made by analyzing the matrix elements of various operators entering the mass formula. These matrix elements are calculated by the help of isoscalar factors of the permutation group, specially derived for this purpose as a function of N c . We also compare two distinct methods used in the study of the [70, 1 − ] multiplet. In the first method the generators are divided into two parts, one part acting on a subsystem of N c − 1 quarks called core and another on the separated quark. In the second method the system is treated as a whole. We show that the latter is simpler and allows to clearly reveal the physically important operators in the mass formula.

Abstract.We present results showing that, thanks to axion-photon mixing in external magnetic fields, it is actually possible to produce an effect similar to the one needed to explain the large-scale coherent orientations of quasar polarisation vectors in visible light that have been observed in some regions of the sky.

Abstract.A model for anomalous J/Ψ suppression in high energy heavy ion collisions is presented. As the additional suppression mechanism beyond standard nuclear absorption inelastic J/Ψ scattering with hadronic matter is considered. Hadronic matter is modeled as an evolving multi-component gas of point-like non-interacting particles (MCHG). Estimates for the sound velocity of the MCHG are given and the equation of state is compared with Lattice QCD data in the vicinity of the deconfinement phase transition. The approximate cooling pattern caused by longitudinal expansion is presented. It is shown that under these conditions the resulting J/Ψ suppression pattern agrees well with NA38 and NA50 data.

We summarise the perspectives on heavy-quarkonium production at the LHC, both for proton-proton and heavy-ion runs, as emanating from the round table held at the HLPW 2008 Conference. The main topics are: present experimental and theoretical knowledge, experimental capabilities, open questions, recent theoretical advances and potentialities linked to some new observables.Comment: Summary of the round table on quarkonium production held at the Joint Meeting Heidelberg-Liege-Paris-Wroclaw: Three Days of Strong Interactions and Astrophysics (HLPW08), Spa, Liege, Belgium, 6-8 March 2008. 30 pages, 12 figures, LaTeX, uses aip-6s.clo, aipproc.cls and aipxfm.sty (included