1 / 38

Newport Beach, CA 25 October 2012

Overview of Medium Energy Physics (“Cold QCD”): Presentation to the Hadron Physics Town Meeting (Presentation to the 2007 NSAC Long Range Plan Implementation Subcommittee) Roy J. Holt. Newport Beach, CA 25 October 2012. Key questions in hadron physics.

cybele
Télécharger la présentation

Newport Beach, CA 25 October 2012

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Overview of Medium Energy Physics (“Cold QCD”): Presentation to the Hadron Physics Town Meeting(Presentation to the 2007 NSAC Long Range Plan Implementation Subcommittee)Roy J. Holt Newport Beach, CA 25 October 2012

  2. Key questions in hadron physics • What is confinement and how is it connected with dynamical chiral symmetry breaking, the origin of more than 98% of visible mass in the Universe?  • What are the dynamics underlying elastic and transition form factors and structure functions of hadrons? How does valence quark structure affect the sea? • Where is the missing spin in the nucleon? Are there significant contributions from gluons or valence quark orbital angular momentum? • Can we reveal a novel landscape of nucleon substructure through measurements of new multidimensional distribution functions? • Do gluonic excitations have a role in the spectroscopy of light mesons and baryons? • How do nuclei emerge from QCD? • What is the relation between short-range N-N correlations and the partonic structure of nuclei? Argonne National Laboratory

  3. Form factors describing nucleon shape/structure Elastic electron scattering from a nucleon j=<e’||e> J=<p’||p> Deep inelastic scattering Nucleon vertex: 1990 Nobel Prize Dirac Pauli 1961 Nobel Prize Cross section for scattering from a point-like object Argonne National Laboratory

  4. Tremendous advances in electron scattering • Unprecedented capabilities: • High Intensity • High Duty Factor • High Polarization- M. Poelker (2012 Lawrence Award) • Large acceptance detectors • State-of-the-art polarimetry, polarized targets Focal plane polarimeter – Jefferson Lab Polarized 3He target Argonne National Laboratory

  5. The proton form factor: Re-wrote the textbooks proton neutron Polarization measurements ) Revolutionized our knowledge  NP2010 Two-photon experiments: OLYMPUS (DESY), JLab, Novosibirsk Argonne National Laboratory

  6. Flavor separation of proton form factors • Very different behavior for u & d quarks • Evidence for diquark correlations – axial diquark -> soft f.f. Q4F2q/k Cates, de Jager, Riordan, Wojtsekhowski, PRL 106 (2011) 252003 Q4 F1q NSAC milestone HP4 (2010) completed Thanks to Craig Roberts

  7. Only JLab 12 GeV can access these form factors to ~10 GeV2 Locations of the zeroes depend on the relative probability of finding scalar & axial diquarks in proton Requires SBS Plot credit: JLab whitepaper Six 12-GeV experiments Argonne National Laboratory

  8. Proton Radius Puzzle 7 s PSAS 2012 Symposium ECT* Workshop - Nov. 2012 rp≅0.8768(69)fm (ep atom) rp≅0.8772(46)fm (ep scattering) rp=0.84184(67)fm (μp atom) Future sub 1% measurements: (1) ep elastic scattering at JLab (2) μp elastic scattering at PSI - 16 U.S. institutions! (~$2 M, no contingency) X. Zhan et al, PLB 705 (2011) 59 Argonne National Laboratory Thanks to R. Gilman, H. Gao

  9. Hadron polarizabilities – Compton scattering • High Intensity Gamma Source (HIgS) • Proton, neutron – polarized H target • Polarized 3He target (9 U.S. institutions) • MAMI (3 U.S. institutions) • Polarized hydrogen target + Crystal Ball • Complete proton in 2014, begin neutron “Faraday effect” HIgS projection D. Shukla, A. Nogga, D. Phillips, PRL (2007) • Lattice calculations • Chiral perturbation theory • Interplay of “pion cloud” and shorter distance effects • Pion polarizability • COMPASS –II (CERN) • (UIUC) Thanks to H. Gao, H. Griesshammer, D. Phillips, W. Briscoe, R. Miskimen, B. Norum Argonne National Laboratory

  10. hadronic leptonic Structure function Parton model Quark charge Prob. of q in proton Partonic structure of the nucleon Three longitudinal structure functions: EIC whitepaper Argonne National Laboratory

  11. SU(6) Upgraded JLab has unique capability to define the valence region Helicity conservation Scalar diquark The Neutron Structure Function Parton model -> • Proton structure function: • Neutron structure function (isospin symmetry): • Ratio: • Focus on high x: • Three 12-GeV experiments • Proton : PVDIS and SoLID (K. Paschke) • Deuteron: radial TPC and CLAS12 • 3H/3He: 3H target and existing spectrometers DSE NSAC milestone HP14 (2018) Argonne National Laboratory Thanks to C. Keppel, K. Kumar, G. Petratos

  12. Spin Structure of the neutron – valence region Polarized electron scattering from a polarized nucleon NSAC milestone HP14 (2018) Three 12-GeV experiments (benefits from SoLID) Thanks to N. Makins, Z.-E. Meziani Courtesy of Z.-E. Meziani, K. Griffioen, S. Kuhn, G. Petratos

  13. Tensor charge from transversity measurements at JLab Distribution of transversely polarized quarks inside a transversely polarized proton Tensor Charge Collins fragmentation function from KEK-B/Belle - M. Grosse-Perdekamp (UIUC) dd benefits from SoLID Two 12-GeV experiments Thanks to A. Prokudin and Z.-E. Meziani Argonne National Laboratory

  14. Drell-Yan is the best way to measure anti-quark distributions What is the A dependence of antiquarks? Experiment E906 FNAL: 3 national labs, 7 U. S. universities, 3 off-shore national labs, 4 off-shore universities Commissioning run completed No model predicts dbar/ubar <1. Longer term: Polarized FNAL, J-PARC at 50 GeV (beyond 2017)? Thanks to D. Geesaman, P. Reimer, J.-C. Peng Argonne National Laboratory

  15. HERMES Surprise! Strange quark distribution • Deep inelastic scattering with flavor tagging • Serious discrepancy with decades of neutrino data Intrinsic sea? Future: COMPASS-II at CERN (2015), JLab with12 GeV (RICH) A. Airapetian et al, PLB 666 (2008) 446 Thanks to H. Jackson, J.-C. Peng

  16. Strange sea and LHC • Parton distribution uncertainties at high x feed into benchmark LHC processes rs = ½( s + sbar)/dbar • Sea appears to be flavor symmetric at low x, consistent with HERMES ATLAS Collaboration, ArXiV:1203.4051 [hep-ex] Thanks to T. LeCompte Argonne National Laboratory

  17. Worldwide quest: spin structure of the nucleon • From DIS measurements DS ≈ 0.3 DG = 1.0±1.2 • quark polarization Dq(x) first 5-flavor separation from HERMES: Dq ≈ 0 RHIC-spin: future charge- current measurements • gluon polarizationΔG(x) RHIC-spin, HERMES, COMPASS • orbital angular momentum L  GPD’s and TMD’s What is the origin of the proton spin? Spin budget of the proton 30% 70% Jets, pions, ALL Far future: EIC

  18. Measurement of the gluon polarization DG at RHIC Dominates at low pT Dominates at high pT D. de Florian et al, Prog. in Part. Nucl. Phys. 67 (2012) 251 0.2 ʃdxDg(x,Q2=10GeV2) = 0.13 (error?) 0.05 RHIC whitepaper See E. Aschenauer’s talk for impact of 2013-14 experiments.

  19. W production expected from RHIC runs 12+13 See E. Aschenauer’s talk for impact on • Provides an important check of SIDIS method • No fragmentation function • Q2=MW2 (no high twist effects) and NSAC milestone HP8 (2013) B. Jacak, N. Xu, RHIC PAC 2012 http://www.bnl.gov/npp/pac0612.asp Thanks to E. Aschenaur Argonne National Laboratory

  20. Is there a flavor asymmetry in the sea quark helicity distributions? • Sea quark polarization at high x • JLab 12 GeV (Hall B) • Kaon detection - RICH Plot credit: K. Hafidi Argonne National Laboratory

  21. Multidimensional parton distribution functions Generalized parton distribution functions Transverse momentum distribution functions eg., Sivers distribution JLab whitepaper eighteen 12-GeV experiments! Separate talk: M. Guidal Argonne National Laboratory

  22. DIS Drell-Yan Transverse Momentum Distributions: The Sivers effect • NSAC Milestone HP13 (2015) “Test unique QCD predictions for relations between single-transverse spin phenomena in p-p scattering and those observed in deep-inelastic scattering.” • COMPASS-II, RHIC-spin, polarized FNAL HERMES Thanks to H. Jackson, M. Burkhardt

  23. Polarized Drell-Yan and W production (2014+) STAR polarized Delivered 500 pb-1 PHENIX FNAL Polarized SeaQuest (>2017) 8 U.S. institutions, 4 off-shore institutions ~$10.5M including 50% contingency COMPASS-II (2014, if upgraded) 1 U. S. institution ~ $0.9M NSF (large area trackers) Thanks to E. Aschenauer, W. Lorenzon, M. Liu, M. Grosse-Perdekamp Forward upgrades -> transverse spin asymmetries Argonne National Laboratory

  24. e’ ~ e t g H, H, E, E (x,ξ,t) g* (Q2) x+ξ x-ξ ~ p’ p dx Eq(x,x,t) = Fq2(t) dx Hq(x,x,t) = Fq1(t) ~ Axial-Vector:H (x,ξ,t) Pseudoscalar:E (x,ξ,t) ~ ~ Quark angular momentum (Ji’s sum rule) Hq(x,0,0) = Dq(x) 1 ( H(x,x,t=0) + E(x,x,t=0) ) x dx = Jquark =1/2 DS+ D Lz X. Ji, Phy.Rev.Lett.78,610(1997) -1 Generalized parton distributions and DVCS Vector:H (x,ξ,t) Tensor:E (x,ξ,t) Forward limit (t →0, x→0) Hq(x,0,0) = q(x) Sum rules A. Radyushkin, PRD 56 (1996) 5524 C. Munoz Comacho et al, PRL 97 (2006) 262002 ; F. X. Girod et al, PRL 100 (2008)162002.

  25. Extraction of quark total angular momentum • DVCS is the “golden channel”: • g* + N -> g + N’ • “Lattice + experiment provides a much greater constraint on GPDs than from either alone.” - J. Negele • Major program for JLab 12 GeV, COMPASS-II, EIC NSAC milestones HP11 (2012), HP9 (2014) Plot credit: JLab whitepaper

  26. DVCS measurements and imaging Thanks to Z.-E. Meziani, JLab whitepaper Argonne National Laboratory

  27. “Valence” gluon can add one unit of angular momentum. A new form of matter: Matter formed from the force field (gluons): Conventional mesons: • meson spin • intrinsic parity • charge conjugation K. Juge et al, nucl-th:030711 separate talk: J. Dudek Thanks to C. Meyer, C. D. Roberts

  28. R M Search for exotic hybrid mesons at the 12-GeV JLab Two 12-GeV JLab experiments Hybrids are predicted by modern QCD treatments: DSE, lattice NSAC milestone HP15 (2018) Complementary work: GSI (PANDA) : antiproton-proton annihilation in charmonium region (2017-) (Northwestern U.) BES-III: electron-positron annihilation in charmonium region – also decays to light quark bound states (Indiana U.) Plot credit: NP2010 Thanks to K. Seth, M. Shepherd, J. Dudek Argonne National Laboratory

  29. Baryon spectrum from EBAC & Bonn-Ga (PDG12) Baryon resonances – JLab Physics Analysis Center Future: J-PARC, Mainz 6 U. S. institutions • Previous (p,2p) data in the N* mass range are all from 1970’s bubble chambers! • New Lattice calculations: arXiv:1201.2349 • N* resonances and exotic baryons. • Coupled channels dynamics are essential! Kamano, Nakamura, Lee et al., 2012 NSAC milestones HP3 (2009) completed, HP7 (2012) Thanks to K. Hicks, W. Briscoe, M. Pennington, T.-S. H. Lee Argonne National Laboratory

  30. A look at quarks in the nucleus: the EMC effect • EMC effect discovered 1982 (H. Montgomery et al.), remains a mystery today • Scattering from quarks in a nucleus is not just a superposition of scattering from quarks in nucleons • Dependence on nuclear density, short range correlations, flavor, spin, isospin? SLAC E-139, 1984, J. Gomez et al. J. Seeley et al, PRL 103 (2009) Argonne National Laboratory

  31. EMC effect and short range N-N interaction • EMC effect is correlated with short range N-N interaction – L. Weinstein et al, PRL 106, 052301 (2011) , J. Arrington et al, arXiv:1206.6343 • Flavor, isospin and spin dependence of EMC effect? JLab@12, Drell-Yan, MINERvA • Plot credit: JLab whitepaper SRC Scaling factors xB ≥ 1.5 N. Fomin et al, PRL 108, 092502 (2012) Four JLab 12 GeV experiments

  32. MINERnAMain Injector ExpeRiment ν-A • MINERvA is studying A dependence of neutrino interactions in unprecedented detail, with He, C, Scintillator (CH), H2O, Fe, Pb targets. • Uses high intensity NuMI Beamline at FNAL with MINOS near detector as muon spectrometer • Nuclear physics goals • High precision measurement of the axial form factor to high Q2 and search for A dependence of form factor • Studies of quark-hadron duality in neutrino interactions, complementing Jlab • Studying partonic nuclear effects with neutrino interactions • Precision cross section measurements and studies of final states • Schedule • Low E ν and anti-ν (average E ~4 GeV) 11/09-4/12 • ~1.7 Million ν CC interactions and 250 K anti-ν CC interactions on scintillator, ~300 K ν CC interactions on Fe and Pb • Medium E ν(avg E ~8 GeV) spring 2013 to about 2019 • MEP Participation • Hampton, Rutgers – PMT detector construction and testing, scintillator plane construction. He target funded by MEP • Slide credit: R. Ransome

  33. 12 GeV Anticipated Data: 1035 cm-2s-1 Hadronization and quark propagation in nuclear matter • What governs the transition of quarks and gluons into pions and nucleons? NSAC 2007 • Production length • Parton energy loss • Formation length • Color transparency • Hadron multiplicity • pT broadening CEBAF @ 12 GeV + CLAS12: ideal facility to study light quark hadronization: W. Brooks, K. Hafidi, K. Joo et al.

  34. Source: EIC whitepaper The EIC (>2020) Gluon imaging Gluon saturation Quark propagation Gluon and sea quark polarization Sea quark imaging Argonne National Laboratory

  35. 2020 and beyond: Electron Ion Collider SRF linac Warm large booster (up to 20 GeV) Pre-booster Brookhaven National Lab Jefferson Lab Transfer beam line Ion source “We recommend the allocation of resources to develop accelerator and detector technology necessary to lay the foundation for a polarized Electron-Ion Collider.” NSAC LRP 2007 Cold ion collider ring (up to 100 GeV) Electron collider ring (3 to 11 GeV) Medium energy IP Injector 12 GeV CEBAF Unique: high-luminosity with polarized electrons, nuclear and polarized ion beams

  36. Non-JLab, non-RHIC cold-QCD experiments Hadron program at HIGS (next 3 years) Future program at HIGS (beyond 3 years) • Chiral Dynamics using photopion production • Spin Polarizabilities of the neutron • Static- Electromagnetic-Polarizabilities • of the proton and neutron • Spin Polarizabilities of the proton • Spin Structure and the Gerasimov-Drell-Hearn (GDH) Sum Rule Measurements Thanks to C. Howell *Expected Argonne National Laboratory

  37. Concluding statement • Understanding hadrons will be one of nuclear physics’ greatest contributions to science • New 21st century tools have positioned us well for the next decade: • JLab 12 GeV, RHIC - Major U.S. facilities lead the world • FNAL – MI, CERN COMPASS-II, HIgS, Mainz, J-PARC, FAIR provide targeted experiments that complement the central program • Far future: EIC • We are camped on one of the most interesting frontiers in science Argonne National Laboratory

  38. Many thanks to • Helpful documents: • NP2010 Report • NSAC 2007 Long Range Plan • Whitepaper drafts: • JLab 12 GeV • The Case for Continuing RHIC Operations • Electron Ion Collider • JLab12, RHIC, COMPASS-II proposals • STAR and PHENIX decadal plans • NSAC Performance Measures 2008 M. Ahmed E. Aschenauer J. Arrington T. Barnes D. Beck W. Briscoe M. Burkhardt G. Cates A. Desphande C. Djalali E. Downie R. Ent C. Gagliardi H. Gao D. Geesaman R. Gilman H. Griesshammer M. Grosse-Perdekamp K. Hafidi K. Hicks C. Howell B. Jacak H. Jackson K. Joo B. Keister C. Keppel W. Korsch K. Kumar T.-S. H. Lee M. Liu W. Lorenzon T. LeCompte N. Makins C. Meyer Z.-E. Meziani R. McKeown R. Milner R. Miskimen H. Montgomery J. Nagle B. Norum K. Orginos K. Paschke J.-C. Peng M. Pennington D. Phillips G. Petratos J. Qiu R. Ransome P. Reimer C. Roberts J. Rubin K. Seth M. Shepherd M. Stratmann B. Surrow S. Vigdor W. Vogelsang H. Weller R. Wiringa B. Wojtsekhowski N. Xu Argonne National Laboratory

More Related