Un modèle de particule à spin de masse nulle dans le champ de gravitation

This unpublished over than forty years old thesis -- in French -- deals with ''A model of massless spinning particle in the gravitational field''.This model is built in the framework of the Souriau's one for spinning particles in general relativity.First, the most general equations for the motion of massless spinning particles are carried out.Then, an analytical solution is found for the de Sitter's universe as a homogeneous one: it brings out no new effect.In the frame of the Swcharzschild's solution of the Einstein's equations, new phenomenons are predicted by the means of a numerical resolution of the equations yield by this model.Among them, a tiny birefringence--like effect is predicted between right and left hand polarized photons, as an example of massless particles.But it was far from being measurable then in the situations which were studied therein.However, a new interest for this kind of model has recently raised.Cette thèse non publiée et datant de plus de quarante ans -- en français -- traite d'"Un modèle de particule à spin de masse nulle dans le champ de gravitation".Ce modèle est construit dans le cadre de celui de Souriau pour des particules à spin en relativité générale.D'abord les équations les plus générales pour le mouvement de particules à spin de masse nulle sont obtenues.Ensuite, une solution analytique est trouvée dans le cas de l'univers de de Sitter en tant qu'univers homogène: elle n'apporte aucun effet nouveau.Dans le cadre de la solution de Schwarzschild des équations d'Einstein, de nouveaux phénomènes sont prédits par l'intermédiaire d'une résolution numérique des équations déduites de ce modèle.Parmi ceux-ci, un minuscule effet analogue à la biréfringence est prédit entre les photons polarisés à droite et à gauche, pris comme exemple de particules sans masse.Mais il était loin d'être mesurable dans les situations qui y étaient alors étudiées.Toutefois, un nouvel intérêt pour ce type de modèle est apparu récemment

J/ψ\psi and ψ′\psi' production in p, O and S induced reactions at SPS energies

The production of the \jpsi\ and \psip\ charmonia states has been studied, through their dimuon decay, in proton, Oxygen and Sulphur induced reactions, by the NA38 experiment at the CERN SPS. The proton data was collected with beams of 200 and 450~GeV, while the ion beams had an energy of 200~GeV per incident nucleon. The \jpsi\ production cross-section per nucleon-nucleon collision exhibits a remarkably continuous pattern, as a function of the product of the mass numbers of the interacting nuclei, from pp up to S-U reactions. The same pattern is observed within S-U collisions, as a function of the collision centrality. While in p-A interactions both charmonia states exhibit the same A-dependence, in \mbox{S-U} collisions the \psip\ production is very strongly suppressed

Transverse momentum of J/ψ,ψ′\psi,\psi' and mass continuum muon pairs produced in 32^{32}S-U collisions at 200 GeV/c per nucleon

F. Fialkoff's has led us to wonder about the most widely borrowed novels in public libraries and how they are promoted. We analysed the best lending statistics in three libraries in Lorraine (North-East France) and tried to identify the most frequently borrowed novels. This project led us to exchange ideas with librarians. We would like to find out about their presuppositions and thus, know more about libraries because we will know about librarians better. This study allows to compare how the librarians apprehend reading and how readers do. We would like to show the gap between the two representations

Centrality dependence of the charged-particle multiplicity density at mid-rapidity in Pb-Pb collisions at sNN\sqrt{s_{NN}} = 2.76 TeV

The centrality dependence of the charged-particle multiplicity density at mid-rapidity in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV is presented. The charged-particle density normalized per participating nucleon pair increases by about a factor 2 from peripheral (70-80%) to central (0-5%) collisions. The centrality dependence is found to be similar to that observed at lower collision energies. The data are compared with models based on different mechanisms for particle production in nuclear collisions.The centrality dependence of the charged-particle multiplicity density at mid-rapidity in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV is presented. The charged-particle density normalized per participating nucleon pair increases by about a factor 2 from peripheral (70-80%) to central (0-5%) collisions. The centrality dependence is found to be similar to that observed at lower collision energies. The data are compared with models based on different mechanisms for particle production in nuclear collisions

Suppression of charged particle production at large transverse momentum in central Pb–Pb collisions at √sNN=2.76 TeV

Inclusive transverse momentum spectra of primary charged particles in Pb–Pb collisions at √sNN=2.76 TeV have been measured by the ALICE Collaboration at the LHC. The data are presented for central and peripheral collisions, corresponding to 0–5% and 70–80% of the hadronic Pb–Pb cross section. The measured charged particle spectra in |η|<0.8 and 0.3<pT<20 GeV/c are compared to the expectation in pp collisions at the same sNN, scaled by the number of underlying nucleon–nucleon collisions. The comparison is expressed in terms of the nuclear modification factor RAA. The result indicates only weak medium effects (RAA≈0.7) in peripheral collisions. In central collisions, RAA reaches a minimum of about 0.14 at pT=6–7 GeV/c and increases significantly at larger pT. The measured suppression of high-pT particles is stronger than that observed at lower collision energies, indicating that a very dense medium is formed in central Pb–Pb collisions at the LHC

Two-pion Bose–Einstein correlations in central Pb–Pb collisions at √sNN=2.76 TeV

The first measurement of two-pion Bose–Einstein correlations in central Pb–Pb collisions at √sNN=2.76 TeV at the Large Hadron Collider is presented. We observe a growing trend with energy now not only for the longitudinal and the outward but also for the sideward pion source radius. The pion homogeneity volume and the decoupling time are significantly larger than those measured at RHIC

Rapidity and transverse momentum dependence of inclusive J/ψ production in pp collisions at √s=7 TeV

The ALICE experiment at the LHC has studied inclusive J/ψ production at central and forward rapidities in pp collisions at √s=7 TeV. In this Letter, we report on the first results obtained detecting the J/ψ through the dilepton decay into e+e− and μ+μ− pairs in the rapidity ranges |y|<0.9 and 2.5<y<4, respectively, and with acceptance down to zero pT. In the dielectron channel the analysis was carried out on a data sample corresponding to an integrated luminosity Lint=5.6 nb−1 and the number of signal events is NJ/ψ=352±32(stat.)±28(syst.); the corresponding figures in the dimuon channel are Lint=15.6 nb−1 and NJ/ψ=1924±77(stat.)±144(syst.). The measured production cross sections are σJ/ψ(|y|<0.9)=10.7±1.0(stat.)±1.6(syst.)−2.3+1.6(syst.pol.)μb and σJ/ψ(2.5<y<4)=6.31±0.25(stat.)±0.76(syst.)−1.96+0.95(syst.pol.)μb. The differential cross sections, in transverse momentum and rapidity, of the J/ψ were also measured

Transverse momentum spectra of charged particles in proton–proton collisions at √s=900 GeV with ALICE at the LHC

The inclusive charged particle transverse momentum distribution is measured in proton–proton collisions at s=900 GeV at the LHC using the ALICE detector. The measurement is performed in the central pseudorapidity region (|η|<0.8) over the transverse momentum range 0.15<pT<10 GeV/c. The correlation between transverse momentum and particle multiplicity is also studied. Results are presented for inelastic (INEL) and non-single-diffractive (NSD) events. The average transverse momentum for |η|<0.8 is 〈pT〉INEL=0.483±0.001 (stat.)±0.007 (syst.) GeV/c and 〈pT〉NSD=0.489±0.001 (stat.)±0.007 (syst.) GeV/c, respectively. The data exhibit a slightly larger 〈pT〉 than measurements in wider pseudorapidity intervals. The results are compared to simulations with the Monte Carlo event generators PYTHIA and PHOJET

ALICE addentum to the Technical Design Report of the time of flight system (TOF)

ALIC

ALICE Technical Design Report on Forward Detectors : FMD, T0 and V0

ALICE PHASE EI SEP ACC S2