J/ΨJ/\Psi yield vs. multiplicity in proton-proton collisions at the LHC

We address the question of understanding the production of $J/\psi$ particles regarding the global underlying event in proton-proton collisions. To do so, we propose to look at a new observable: the $J/\psi$ production as a function of the charged particles multiplicity of the event. We demonstrate the interest for an experimental measurement by varying the model of multiple interactions in the PYTHIA generator.Comment: 4 pages, 2 figures, QUARKONIUM 2010: Three Days Of Quarkonium Production in pp and pA Collisions, 29-31 Jul 2010, Palaiseau, Franc

Measurement of J/Psi production in pp collisions at sqrt(s)=2.76 and 7 TeV with ALICE

We present results from the ALICE experiment on the inclusive J/Psi production in pp collisions at sqrt(s)=2.76 and 7 TeV. The integrated and differential cross sections are evaluated down to pT=0 in two rapidity ranges, |y|<0.9 and 2.5<y<4, in the dielectron and dimuon decay channel respectively. The measurement at sqrt(s)=2.76 TeV, the same energy as Pb-Pb collisions, provides a crucial reference for the study of hot nuclear matter effects on J/Psi production. The J/Psi yield in pp collisions at sqrt(s)=7 TeV has also been studied as a function of the charged particle multiplicity and first results are presented.Comment: 4 pages, 4 figures, parallel talk at Quark Matter 2011, Annecy, Franc

Heavy-flavour and quarkonium production in the LHC era: from proton-proton to heavy-ion collisions

This report reviews the study of open heavy-flavour and quarkonium production in high-energy hadronic collisions, as tools to investigate fundamental aspects of Quantum Chromodynamics, from the proton and nucleus structure at high energy to deconfinement and the properties of the Quark-Gluon Plasma. Emphasis is given to the lessons learnt from LHC Run 1 results, which are reviewed in a global picture with the results from SPS and RHIC at lower energies, as well as to the questions to be addressed in the future. The report covers heavy flavour and quarkonium production in proton-proton, proton-nucleus and nucleus-nucleus collisions. This includes discussion of the effects of hot and cold strongly interacting matter, quarkonium photo-production in nucleus-nucleus collisions and perspectives on the study of heavy flavour and quarkonium with upgrades of existing experiments and new experiments. The report results from the activity of the SaporeGravis network of the I3 Hadron Physics programme of the European Union 7th Framework Programme

Status of Quarkonium Database

Physics Working Group "DataBase on Quarkonia results

A database for quarkonium and open heavy-flavour production in hadronic collisions with HepData

12 pages, 8 figuresWe report on the creation of a database for quarkonium and open heavy-flavour production in hadronic collisions. This database, made as a collaboration between HepData and the ReteQuarkonii network of the integrating activity I3HP2 of the 7th Framework Programme, provides an up-to-date review on quarkonia and open heavy-flavour existing data. We first present the physics motivation for this project, which is connected to the aim of the ReteQuarkonii network, studies of open heavy-flavour hadrons and quarkonia in nucleus-nucleus collisions. Then we give a general overview of the database and describe the HepData database for particle physics, which is the framework of the quarkonia database. Finally we describe the functionalities of the database with as example the comparison of the production cross section for the J/$\psi$ meson at different energies

Multiplicity and transverse-momentum dependence of two- and four-particle correlations in pPb and PbPb collisions

Measurements of two- and four-particle angular correlations for charged particles emitted in pPb collisions are presented over a wide range in pseudorapidity and full azimuth. The data, corresponding to an integrated luminosity of approximately 31 inverse nanobarns, were collected during the 2013 LHC pPb run at a nucleon-nucleon center-of-mass energy of 5.02 TeV by the CMS experiment. The results are compared to 2.76 TeV semi-peripheral PbPb collision data, collected during the 2011 PbPb run, covering a similar range of particle multiplicities. The observed correlations are characterized by the near-side (abs(Delta(phi)~0) associated pair yields and the azimuthal anisotropy Fourier harmonics (v[n]). The second-order (v[2]) and third-order (v[3]) anisotropy harmonics are extracted using the two-particle azimuthal correlation technique. A four-particle correlation method is also applied to obtain the value of v[2] and further explore the multi-particle nature of the correlations. Both associated pair yields and anisotropy harmonics are studied as a function of particle multiplicity and transverse momentum. The associated pair yields, the four-particle v[2], and the v[3] become apparent at about the same multiplicity. A remarkable similarity in the v[3] signal as a function of multiplicity is observed between the pPb and PbPb systems. Predictions based on the color glass condensate and hydrodynamic models are compared to the experimental results