Workshop on nuclear Parton Distribution Functions

22 févr. 2010, 09:00 → 23 févr. 2010, 18:30 Europe/Paris

Auditorium M. Vivargent (LAPTH)

Christophe Furget (LPSC), François Arleo (LAPTH), Ingo Schienbein (LPSC), Magali Estienne (Subatech)

The workshop is intended to discuss informally various aspects of nuclear parton distribution functions (nPDF). Several topics could be discussed, in particular: * Current knowledge on nPDF, status on global fit analyses * Uncertainties and consequences on various observables (prompt photons, heavy quarkonia, jets, ...) * Future constraints on nPDF in p-A and A-A collisions at the LHC * Link between nPDF and saturation Ample time will be given for informal discussions. One of the goals of the workshop is to federate the activities of various groups in France. In particular it aims at enhancing exchanges between theorists and experimentalists on this topic. It is partly funded by the CNRS program "Projets Exploratoires Pluridisciplinaires - Physique Théorique et ses Interfaces" submitted by the organisers of the workshop.

lun. 22 février

09:30 → 12:00 nPDF and saturation

slides Milhano.pdf

09:30 Gluon saturation and nuclear PDFs

I will discuss the topic of gluon saturation at small x, and what it implies for the use of nuclear parton distribution functions.

Orateur: Dr Francois Gelis (IPhT)

Slides Gelis.pdf

10:20 break

10:50 Non-linear QCD meets data: from proton to nuclei

Orateur: José Guilherme Milhano (CENTRA-IST & CERN-PH-TH)

11:25 Saturation effects in p-A collisions at the LHC with the ALICE muon spectrometer

At very high energies or small values of Bjorken x, the increase of parton density in hadronic matter is expected to lead to a saturated partonic distribution regime. It has been suggested that such an initial state effect, expected to be present before the Quark Gluon Plasma phase, has been observed in heavy-ion collisions at RHIC energies. The study of high partonic density effects in QCD can be formulated in terms of an effective field theory, the Color Glass Condensate (CGC). This theoretical framework is used in particular to describe the new kinematic regime that is accessible at the LHC in p-A collisions. In this talk the principal features of the high density regime will be described, together with a brief look at the experimental observations for saturation effects obtained at RHIC energies. Special attention will be given to the prospects of observing saturation effects at the LHC in p-A collisions with the ALICE experiment. In particular, heavy flavour and quarkonia production will be discussed in terms of physics performance studies of the ALICE Muon Forward Spectrometer.

Orateur: Cynthia Hadjidakis (IPN)

Slides Hadjidakis.pdf

12:00 → 14:15 Lunch

14:15 → 18:05 Heavy flavour

14:15 "Quarkonia as tools ?" : further experimental needs

Orateur: Dr Jean-Philippe Lansberg (Ecole Polytechnique - CPhT)

15:05 Cold Nuclear Matter effects on J/psi production with extrinsic transverse momentum

%----------------------------------------------------------------------------- % THIS IS THE CONFERENCE TEMPLATE % % Do not modify the dimensions of the page % No paragraph indent or paragraph skip % \documentclass[11pt]{article} % \pagestyle{empty} \setlength{\topmargin}{-0.3in} \setlength{\textheight}{9.9in} \setlength{\oddsidemargin}{-0.1in} \setlength{\textwidth}{6.5in} \parindent=0pt \parskip=0pt % % list of words for which Latex has wrong hyphenation points %\hyphenation{ave-ra-ge un-der-lying} % \begin{document} % {\small \it Workshop on Nuclear Parton Distribution Functions, LAPTH Annency, Feb. 22 - 23, 2010} \vspace{0.5in} \centerline{\Large \bf Cold Nuclear Matter effects on $J/\psi$ production} \centerline{\Large \bf with extrinsic transverse momentum} \vspace{8pt} \centerline{ {\bf E.~G.~Ferreiro}$^{\rm a}$, {\bf F.~Fleuret}$^{\rm b}$, {\bf J.~P.~Lansberg}$^{\rm c}$ and {\bf A.~Rakotozafindrabe}$^{\rm d}$} \vspace{8pt} \centerline{\small$^{\rm a}$Departamento de F\'{\i}sica de Part\'{\i}culas, Universidade de Santiago de Compostela }\centerline{15782 Santiago de Compostela, Spain, {\it elena@fpaxp1.usc.es}} \vspace{8pt} \centerline{\small$^{\rm b}$ Laboratoire Leprince Ringuet, \'Ecole Polytechnique, {CNRS-IN2P3}, } \centerline{91128 Palaiseau Cedex, France, {\it fleuret@llr.in2p3.fr}} \vspace{8pt} \centerline{\small$^{\rm c}$ Centre de Physique Th\'eorique, \'Ecole Polytechnique, {CNRS}, } \centerline{91128 Palaiseau Cedex,France, {\it lansberg@cpht.polytechnique.fr}} \vspace{8pt} \centerline{\small$^{\rm d}$ IRFU/SPhN, CEA Saclay }\centerline{91191 Gif-sur-Yvette Cedex, France, {\it andry.rakotozafindrabe@cea.fr}} \vspace{16pt} We study the Cold Nuclear Matter (CNM) effects on $J/\psi$ production, whose understanding is fundamental to evaluate the Quark Gluon Plasma or Hot Nuclear Matter effects. Two CNM effects are of particular importance: the shadowing of the initial parton distributions (PDF) due to the nuclear environment and the nuclear absorption of the $c\bar{c}$-pair. Recent theoretical works~\cite{CSM-upgrade,Upsilon-LHC,next-paper-JPhi} have emphasized that the production mechanism of the $J/\psi$ is not {\it via} a $2 \to 1$ Drell-Yan like process. This modifies the way to compute the nuclear shadowing~\cite{first-extrinsic-paper}. We will present our results in $dA$ and $AA$ collisions at RHIC energy~\cite{first-extrinsic-paper}, using several parametrizations of the nuclear PDF~\cite{paper-nPDF-comparison,second-extrinsic-paper}, and including the $p_T$-dependence of CNM effects up to intermediate values of $p_T$, which are not accessible in the usual studies. \vspace{8pt} \bibliographystyle{unsrt} \begin{thebibliography}{6} \bibitem{CSM-upgrade}H.~Haberzettl and J.~P.~Lansberg, \textit{Phys. Rev. Lett.} {\bf 100}, (2008) 032006. \bibitem{Upsilon-LHC}P.~Artoisenet, J.M.~Campbell, J.P.~Lansberg, F.~Maltoni and F.~Tramontano, \textit{Phys. Rev. Lett.} {\bf 101}, (2008) 152001. \bibitem{next-paper-JPhi}S.J.~Brodsky and J.P.~Lansberg, SLAC-PUB-13736, \textit{arXiv:0908.0754}. \bibitem{first-extrinsic-paper}E.~G.~Ferreiro, J.~P.~Lansberg, F.~Fleuret, A.~Rakotozafindrabe, \textit{Phys. Lett. B} {\bf 680} (2009) 50-55. \bibitem{paper-nPDF-comparison}E.~G.~Ferreiro, J.~P.~Lansberg, F.~Fleuret, A.~Rakotozafindrabe, \textit{arXiv:0903.4908}, Contribution to Rencontres de Moriond~2009: QCD and High Energy Interactions. \bibitem{second-extrinsic-paper}E.~G.~Ferreiro, J.~P.~Lansberg, F.~Fleuret, A.~Rakotozafindrabe, \textit{arXiv:0912.4498}. \end{thebibliography} \end{document}

Orateur: Dr Andry Rakotozafindrabe (CEA Saclay, IRFU/SPhN)

Slides rakotozafindrabe_nPDFworkshop2010.pdf

15:35 Gluon shadowing and J/psi suppression in p A collisions : uncertainties and constraints

Orateur: François Arleo (LAPTH)

Slides arleo.pdf

16:05 break

16:35 The role of parton shadowing in the comparison of p-A and A-A results on J/psi suppression at SPS energies

The observation of an anomalous jpsi suppression in nucleus-nucleus collisions is one of the most important results of the SPS heavy-ion program. An essential ingredient in this result is the determination, obtained by studying p-A collisions, of cold nuclear matter effects. These effects are extrapolated to A-A collisions, determining a reference jpsi yield that is then compared with the measurements. In this article we investigate the role of parton shadowing on the determination of such a reference, and we calculate its effect for In-In and Pb-Pb collisions as a function of rapidity and centrality, for various nPDF parametrizations.

Orateur: Dr Enrico Scomparin (INFN-Torino (Italy))

Slides Enrico.ppt

17:05 Upsilon production in dAu collisions at RHIC

Orateur: Dr Nicolas Matagne (Université de Mons)

Slides Matagne.pdf

17:35 Direct Photon Production In Association With A Heavy Quark Jet at Hadron and Ion Colliders

The associated production of direct photons and heavy quarks probes the gluon and heavy quark PDFs. As such this process can be used to constrain those nPDFs and to distinguish between different nPDF sets. Predictions for hadron and ion colliders (ALICE, RHIC) are shown.

Orateur: Dr Tzvetalina Stavreva (LPSC)

Slides Stavreva.pdf

20:00 → 22:00 Banquet

mar. 23 février

09:15 → 10:35 Global fits

09:15 A Global Analysis of Nuclear PDFs and the Heavy Quark Components

We provide a brief overview of the historical developments of global analyses of nuclear PDFs incorporating heavy quarks into the PDF formalism. We then look at the various data sets which have been used to extract the proton PDF and highlight the necessity of addressing the nuclear dimension in a coherent framework.

Orateur: Prof. Fred Olness (SMU)

Slides Olness.pdf

10:05 Nuclear PDF from neutrino and charged lepton data

Orateur: Dr Karol Kovarik (LPSC Grenoble)

Slides Kovarik.pdf

10:35 → 11:00 break

11:00 → 12:00 Photons

11:00 Prompt Photon Production in p-A Collisions and Gluon Shadowing

We discuss the use of prompt photon production at the LHC to probe the gluon nuclear density, and more specifically the shadowing ratio G_A/G_p that one could access in foreseen p-A runs.

Orateur: M. Thierry Gousset (Subatech)

Slides Gousset.pdf

11:30 How well can isolated photons constrain the gluon pdfs in the proton?

Orateur: Mlle Raphaelle ICHOU (SUBATECH)

Slides Ichou.pdf

12:00 → 14:15 Lunch

14:15 → 17:25 LHC and future facilities

14:15 Constraints to nuclear parton densities in an LHeC

The possibilities to constrain nuclear parton densities through the eA option of the proposed LHeC at CERN will be presented and discussed. Emphasis will be presented in quantitative constrains to DGLAP global analysis, and in the problems due to our limited knowledge of the longitudinal structure function in the nuclear case.

Orateur: Dr Nestor Armesto (Universidade de Santiago de Compostela)

Slides Armesto.pdf

15:05 pA collisions at LHC: a tool to constrain nuclear PDFs

pA collisions at LHC: a tool to constrain nuclear PDFs

Orateur: Mme Paloma Quiroga Arias (Universidade de Santiago de Compostela)

Slides Quiroga.pdf

15:35 Measuring nuclear PDFs at the LHC: a wish list

Orateur: David d'Enterria (ICREA & ICC-UB)

Slides annecy_npdfs10.odp annecy_npdfs10.pdf