Nuclear physics with a medium energy EIC C. Weiss (JLab), POETIC Workshop, Indiana University, Bloomington, 20 Aug 12

Transcription

1 Nuclear physics with a medium energy EIC C. Weiss (JLab), POETIC Workshop, Indiana University, Bloomington, 0 Aug Overview of ep/ea physics with generic medium energy EIC s = 0 70 GeV,L 34 cm s I) 3D structure of nucleon in QCD Sea quark and gluon polarization Spatial distributions, orbital motion Multiparton correlations II) Fundamental color fields in nuclei Nuclear quark/gluon densities Shadowing, coherent processes Color transparency III) Emergence of hadrons from color charge Color neutralization, hadron formation Interaction of color charge with matter Based on review article A. Accardi et al., EPJA48 (0) 9. Input to JLab MEIC Concpetual Design Report (0) Guiding principles Focus on physical system, not formal descriptors: What do we learn about dynamics? Unifying perspective low high energies Science Requirements and Conceptual Design for a Polarized Medium Energy Electron-Ion Collider at Jefferson Lab S. Abeyratne, A. Accardi,7, S. Ahmed, D. Barber 6, J. Bisognano 8, A. Bogacz, A. Castilla 3,7, P. Chevtsov 4, S. Corneliussen, J. Delayen 3, W. Deconinck 5, Ya. Derbenev, S. DeSilva 3, D. Douglas, V. Dudnikov, R. Ent, B. Erdelyi, Yu. Filatov 9,, D. Gaskell, V. Guzey, T. Horn 4, A. Hutton, C. Hyde 3, R. Johnson, Y. Kim 8, F. Klein 4, A. Kondratenko 6, M. Kondratenko 6, G. Krafft,3, R. Li, F. Lin, S. Manikonda, F. Marhauser, R. McKeown, V. Morozov, P. Nadel-Turonski, E. Nissen, P. Ostroumov, M. Pivi 5, F. Pilat, M. Poelker, A. Prokudin, R. Rimmer, T. Satogata, M. Spata, H. Sayed 3, M. Sullivan 5, C. Tennant, B. Terzić, M. Tiefenback, H. Wang, S. Wang, C. Weiss, B. Yunn, Y. Zhang Thomas Jefferson National Accelerator Facility, Newport News, VA 3606, USA Argonne National Laboratory, Argonne, IL 60439, USA 3 Brookhaven National Laboratory, Upton, NY 973, USA 4 Catholic University of America, Washington, DC 0064, USA 5 College of William and Mary, Williamsburg, VA 387, USA 6 Deutsches Elektronen-Synchrotron (DESY), 607 Hamburg, Germany 7 Hampton University, Hampton, VA Idaho State University, Pocatello, ID 8309, USA 9 Joint Institute for Nuclear Research, Dubna, Russia Moscow Institute of Physics and Technology, Dolgoprydny, Russia Muons Inc., Batavia, IL 605, USA Northern Illinois University, De Kalb, IL 605, USA 3 Old Dominion University, Norfolk, VA 359, USA 4 Paul Scherrer Institute, 53 Villigen PSI, Switzerland 5 SLAC National Accelerator Laboratory, Menlo Park, CA 94305, USA 6 Science and Technique Laboratory Zaryad, Novosibirsk, Russia 7 Universidad de Guanajuato, Guanajuato, Meico 8 University of Wisconsin-Madison, Madison, WI 53706, USA Editors: Y. Zhang and J. Bisognano (August, 0)

2 3D nucleon structure: Fields and particles Hadrons in QCD Relativity: Particle creation/annihilation, space time picture frame dependent Strong interactions: Vacuum structure, non perturbative effects Quantum mechanics: Fluctuations Uniquely challenging dynamical system! Field theoretical description Imaginary time t iτ, statistical mechanics Lattice QCD; analytic methods interactions wave function, Q e e Particle based description Parton picture P : Wave function Feynman, Gribov: Closed system. Alt: Light front quantization Components with different particle number Many body system: Constituents, interactions, spatial structure, orbital motion,... High energy process takes snapshot Short distance interactions: Factorization

3 3D nucleon structure: Landscape Theoretical coverage EIC Components probed predominantly > 0. Valence quarks: Source, quantum numbers Also gluons at large! Intrinsic sea s s, c c? Q [GeV ] s = 70 GeV s = 0 GeV Sea quarks, gluons: Quantum numbers Generated by non perturbative QCD interactions! JLab GeV < Gluons, singlet sea: Radiatively generated Saturation at small : New dyn. scale Learn about interactions! saturation QCD radiation non pert. interact radiative gluons/sea sea quarks gluons valence quarks gluons Quantities measured Particle number densities, incl. spin/flavor dependence Transverse spatial distributions PDFs GPDs Orbital motion, angul. momentum TMDs Particle correlations MP distributions, GPDs Densities with operator definition N QCD Op N Calculable with non perturbative methods Scale dependence from RNG equation.

4 3D nucleon structure: Sea quark polarization Spin Interactions? u, s, s π, Κ d How are sea quarks polarized in nucleon? Non-perturbative QCD interactions connecting valence sea quarks Role of mesonic degrees of freedom? 0.3 ( u()- d()) HERMES 5 Flavor EIC 5 on 50 Semi inclusive scattering: Identify particles produced from struck quark Flavor asymmetries poorly constrained by present data HERMES SIDIS First constraints from RHIC W data EIC 5 on 50 GeV 0 days, ^33 Kinney, Seele EIC: Map sea quark distributions and their spin dependence High energy ensures independent fragmentation of struck quark

5 3D nucleon structure: Gluon polarization Interactions? Q What is the polarized gluon distribution? Origin of non-perturbative gluon fields? Constituent quark structure, quark correlations? Spin Gluon contribution to nucleon spin? Orbital angular momentum in wave function? 0.3 G 0. DSSV χ /χ =% band G() presently poorly constrained Q dependence of g (,Q ) EMC/SMC, SLAC, HERMES, COMPASS, JLab 6/ GeV Hard processes in p p RHIC: Recent data EIC: Fully quantitative determination Good results already with medium energy Talk Stratmann 0. EIC EIC stage- data 0-0. Q = GeV M. Stratmann, INT Workshop 0 Quark/gluon orbital angular momentum Much progress in theoretical understanding INT Workshop Feb ; many recent papers Manifest in semi inclusive spin asymmetries e.g. Sivers effect Talk Prokudin Challenge to separate OAM in wave function from QCD final state interactions Talk Burkardt

6 3D nucleon structure: Spatial distributions q + q gluons Q hard GPD J/ψ How are quarks/gluons distributed in transverse space? Fundamental size and shape of nucleon in QCD changes with t Distributions change with : Diffusion, chiral dynamics Input for saturation models, multiparton interactions in pp@lhc dσ T (ep e p J/ψ) / d dq dt [µb / GeV 4 ] s ep = 00 GeV, L = 34 cm - s -, 6 weeks = Weiss INT J/ψ electroproduction 5 < Q < GeV 40 < W < 60 GeV 80 < W < 0 GeV 60 < W < 00 GeV t [GeV ] power-like? Eclusiveprocessesγ +N J/ψ+N Gluonic form factor of nucleon: Generalized parton distribution Other channels γ,ρ 0,π,K sensitive to quarks Talks Hasch, Liuti, Fazio EIC: Gluon imaging of nucleon Luminosity for low rates, differential measurements

7 Color fields in nuclei: Physics modified structure collective effects What are the fundamental color fields in nuclei? Modification of nucleon structure Collective effects A N Non nucleonic degrees of freedom QCD origin of NN interaction at different energies Approach to black disk/saturation regime Interaction with high energy probe Q Transverse resolution r /Q Coherence length l coh ν/q factor l coh Final states: Inclusive, identified spectators, eclusive,...

8 Color fields in nuclei: Landscape 0 Theoretical coverage EIC Fields probed in ea l coh R A : Modified nucleon structure, short range correlations JLab GeV: EMC effect for valence quarks EMC effect for gluons, antiquarks? l coh R A : Collective effects New regime accessible with medium energy EIC! Q [GeV ] s = 70 GeV QCD phenomena 00 0 s = 0 GeV JLab l coh [fm] Shadowing: QM interference in scattering from multiple nucleons Is it different for gluon and quark fields? Color transparency: Disappearance of interaction for small probes σ r Fundamental prediction of QCD as gauge theory Q l coh Coherent scattering: Quark/gluon fields of entire nucleus Nuclear GPDs, quark/gluon size R A Quantum fluctuations: Diffraction Saturation: Strong gluon fields, black disk regime in hard interactions New dynamical scale Qs

9 Color fields in nuclei: Gluon density C C C (, =.69 GeV ) C (, =0 GeV ) C valence quarks sea quarks gluons Q =.69 GeV Q =0 GeV EPS09NLO Eskola et al Shadowing EMC Nuclear quark/gluon densities > EMC effect: Modification of free nucleon structure: Antishadowing: Poorly understood Shadowing: QM interference Gluon poorly constrained Q dependence of nuclear structure function F A (,Q ) ] [ GeV Q MEIC NNPDF analysis Accardi, Dupre INT 4 EIC Stage II EIC Stage I Q = c c c c Q =.5 /3 Q = 0.5A Pb /3 Q =.5A Pb Medium energy EIC: Precise determination of nuclear quark/gluon densities Wide coverage in,q Inportant for understanding approach to saturation at small Shadowing affects nuclear enhancement of Qs

10 Color fields in nuclei: New probes with EIC Spectator tagging Bound nucleon structure: EMC effect tagged Neutron structure from D(e,e p)x JLab BONUS eperiment Requires forward p/n detection V, γ coherent Coherent nuclear processes A(e,e M)A Fundamental quark/gluon radii of light nuclei Kowalski, Caldwell 09: Heavy nuclei, very challeging Impact parameter dependent shadowing Color transparency in meson production Fundamental prediction of QCD transparency Complement to saturation eperiments: Disappearance at high Q

11 Hadrons from color charge: Fragmentation e + e? How do hadrons emerge from QCD color charge? Conversion energy matter Cosmic ray physics, early universe Dynamical mechanisms: QCD radiation, pair creation by soft fields Vacuum structure, q q condensate ep "hole", spin?? Fragmentation functions from e + e Many puzzles: s s, kaons, baryons Essential input to SIDIS EIC: New possibilities Fragmentation functions from ep: Favored unfavored, test universality N F z Correlations Current fragmentation Target fragmentation Target fragmentation: How does nucleon with color hole materialize?, spin dependence Correlations current target regions: Multiparton correlations New field of study: pp at LHC New possibilities for nucleon structure Qualtiatively new! Many applications! Unique for EIC

12 Hadrons from color charge: Matter t F t h? cold QCD matter + h? How does fast color charge interact with hadronic matter? t CN 0 A e q e A A A q hot QCD matter q Energy loss, attenutation Time scales for color neutralization t N, hadron formation t F Multiplicity Ratio Accardi, Dupre INT Z Ratio Vs Q 0.95 HERMES data π + + K EIC error bars h (R is arbitrary) A s = 00 GeV^ 0 < ν < 30 GeV π + + K D Meson 50 < ν < 70 GeV π + + K D Meson Cold vs. hot matter? ea/γa jets in AA EIC: Comprehensive studies Wide range of energy ν = 0 GeV: Move hadronization inside/outside nucleus, distinguish energy loss and attenuation Fied target: Correlations ν Q Wide range of Q : QCD evolution of fragmentation functions and medium effects Q HERMES data π + EIC error bars A (R is arbitrary) h π + (s=00 GeV ) π + (s=00 GeV && 0 < ν < 30 GeV) Hadronization of charm, bottom: Clean probes, QCD predictions High luminosity: Multidimensional binning s > 30GeV: Study jets and their substructure in ea

13 Summary Unique nuclear physics program with medium-energy EIC s = 0-70 GeV Three dimensional structure of nucleon in QCD Fundamental color fields in nuclei Emergence of hadrons from color charge Natural organization... could be sharpened further! Focus on what we learn about the dynamical system Many questions addressed by more than one measurement: Orbital angular momentum inclusive G, semi inclusive asymmetries; Quark correlations eclusive and semi inclusive processes Qualitatively new probes available in ea Spectator tagging, coherent processes: Should be developed further! ep better formalized, but ea completely new