Jean-Philippe LANSBERG
نویسندگان
چکیده
Quarkonia are meson states whose constituents are a charm or bottom quark and its correspondingantiquark (QQ̄). The study of the production of such bound states in high-energy hadron collisions represents an important test for the Quantum Chromo-Dynamics. Despite the fact that the quarkonium saga has already a 40-year history, the quarkonium production mechanism is still an open issue. Therefore, measurements at the new CERN Large Hadron Collider (LHC) energy regimes are extremely interesting.In this thesis, the study of inclusive J/ψ production in proton-proton (pp) collisions at√s = 2.76and 7 TeV, obtained with the ALICE experiment, is presented. J/ψ mesons are measured at forwardrapidity (2.5 < y < 4), down to zeropT, via their decay into muon pairs(μ+μ−). Quarkonium resonances also play an important role in probing the properties of the strongly interacting hadronic matter created, at high energy densities, in heavy-ion collisions. Under such extreme conditions, the created system, according to QCD, undergoes a phase transition from ordi-nary hadronic matter to a new state of deconfined quarks and gluons, called Quark Gluon Plasma (QGP). The ALICE experiment at CERN LHC has been specifically designed to study this state of matter. Quarkonia, among other probes, represents one of the most promising tools to prove the QGP formation. In order to correctly interpret the measurements of quarkonium production in heavy-ion collisions, a solid baseline is provided by the analogous results obtained in pp collisions.Hence, the work discussed in this thesis, concerning the inclusive J/ψ production in pp collisions, also provides the necessary reference for the corresponding measurements performed in Pb-Pb collisions which were collected, by the ALICE experiment, at the very same center-of-mass energy per nucleon pair (√sNN = 2.76 TeV).
منابع مشابه
Di-J/ψ production at the Tevatron and the LHC
We briefly review recent results which we have obtained in the study of J/ψ-pair production at the Tevatron and the LHC. We claim that the existing data set from CMS and D0 point at a significant double-parton-scattering contribution with an effective cross section smaller than that for jet-related observables. We have also derived simple relations involving feed-down fractions from excited sta...
متن کاملHeavy quarkonium production in hadronic collisions
Different theoretical models which attempt to describe hadronic production of heavy quarkonia are reviewed. Firstly, we consider the Color Singlet Model and point out the large discrepancies between the theoretical predictions and the results from the Tevatron detectors. Then some other models are introduced, quickly discussed and confronted with experimental results. Finally, we suggest possib...
متن کاملΥ Production at Hadron Colliders : a Review
We give an overview of the present status of knowledge of the production of J/ψ, ψ′ and Υ in high-energy hadron collisions. We first present two early models, namely the ColourSinglet Model (CSM) and the Colour-Evaporation Model (CEM). The first is the natural application of pQCD to quarkonium production and has been shown to fail dramatically to describe experimental data, the second is its ph...
متن کاملHeavy-Quarkonium Production in High Energy Proton-Proton Collisions at RHIC
We update the study of the total ψ and Υ production cross section in proton-proton collisions at RHIC energies using the QCD-based Color-Singlet (CS) Model, including next-to-leading order partonic matrix elements. We also include charm-quark initiated processes which appear at leading order in αs, but which have so far been overlooked in such studies. Contrary to earlier claims, we show that t...
متن کاملNonlinear dynamic of the multicellular chopper
In this paper, the dynamics of multicellular chopper are considered. The model is described by a continuous time three--dimensional autonomous system. Some basic dynamical properties such as Poincar'e mapping, power spectrum and chaotic behaviors are studied. Analysis results show that this system has complex dynamics with some interesting characteristics.
متن کامل