Elton S. Smith PaNic02, Sep 30 – Oct 4, Physics Prospects with the JLab 12 GeV Upgrade Elton S. Smith Jefferson Lab PANIC02 Osaka Gluonic Excitations 3-dim view of the Nucleon Valence Structure of the Nucleon

Elton S. Smith PaNic02, Sep 30 – Oct 4, JLab Today  Main physics programs ─ nucleon electromagnetic form factors (including strange form factors) ─ N → N* electromagnetic transition form factors ─ spin structure functions of the nucleon ─ form factors and structure of light nuclei  Superconducting recirculating electron accelerator ─ max. energy 5.7 GeV ─ max current 200  A ─ e polarization80%  Simultaneous operation in 3 halls L [cm -2 s -1 ] ─ 2 High Resolution Spectrometers (p max =4 GeV/c)10 39 ─ 2 spectrometers (p max =7 and 1.8 GeV/c) + special equipment10 39 ─ Large Acceptance Spectrometer for e and  induced reactions10 34

Elton S. Smith PaNic02, Sep 30 – Oct 4, GeV CEBAFCHL-2 Upgrade magnets and power supplies 12 Enhance equipment in existing halls add Hall D (and beam line)

Elton S. Smith PaNic02, Sep 30 – Oct 4, Gluonic Excitations Dynamical role of Glue Confinement

Elton S. Smith PaNic02, Sep 30 – Oct 4, Lattice QCD From G. Bali Flux tubes realized Confinement arises from flux tubes and their excitation leads to a new spectrum of mesons → Flux Tube Model

Elton S. Smith PaNic02, Sep 30 – Oct 4, Understanding Confinement The Ideal Experiment The Real Experiment

Elton S. Smith PaNic02, Sep 30 – Oct 4, Hybrid Mesons 1 GeV mass difference (  /r) Hybrid mesons Normal mesons

Elton S. Smith PaNic02, Sep 30 – Oct 4, Normal Mesons – qq color singlet bound states Spin/angular momentum configurations & radial excitations generate our known spectrum of light quark mesons. Starting with u - d - s we expect to find mesons grouped in nonets - each characterized by a given J, P and C. J PC = 0 – – 0 + – 1 – – … Not-allowed: exotic J PC = 0 – – – 1 + – 2 ++ … Allowed combinations

Elton S. Smith PaNic02, Sep 30 – Oct 4, Quantum Numbers of Hybrid Mesons Quarks Excited Flux Tube Hybrid Meson like Exotic Flux tube excitation (and parallel quark spins) lead to exotic J PC

Elton S. Smith PaNic02, Sep 30 – Oct 4, Mass (GeV) qq Mesons L = Each box corresponds to 4 nonets (2 for L=0) Radial excitations (L = qq angular momentum) exotic nonets 0 – – – 1 – + 1 – – 2 – – – + 2 – Glueballs Hybrids Meson Map Lattice GeV GeV GeV

Elton S. Smith PaNic02, Sep 30 – Oct 4, Exotic Signal J PC =1 ─ + E852  1 (1600) →     ↳     ↳  PRL 86, 3977 (2001) M =1.60  0.05  = 0.34  0.06

Elton S. Smith PaNic02, Sep 30 – Oct 4, Families of Exotics  1 I G (J PC )=1 - (1 -+ ) NN  e X  , ,   ’ 1 I G (J PC )=0 + (1 -+ )  1 I G (J PC )=0 + (1 -+ ) K 1 I G (J PC )= ½ (1 - )  1    1   b 1,   ’ 1   Couple to V.M + e 1 -+ nonet

Elton S. Smith PaNic02, Sep 30 – Oct 4,  Use photons to produce meson final states ─ tagged photon beam with 8 – 9 GeV ─ linear polarization to constrain production mechanism  Use large acceptance detector ─ hermetic coverage for charged and neutral particles ─ typical hadronic final states: f 1  KK  KK  b 1   ─ high data acquisition rate  Perform partial-wave analysis ─ identify quantum numbers as a function of mass ─ check consistency of results in different decay modes Strategy for Exotic Meson Search

Elton S. Smith PaNic02, Sep 30 – Oct 4, Coherent Bremsstrahlung flux E  (GeV) 12 GeV electrons This technique provides requisite energy, flux and polarization collimated Incoherent & coherent spectrum tagged with 0.1% resolution 40% polarization in peak electrons in photons out spectrometer diamond crystal

Elton S. Smith PaNic02, Sep 30 – Oct 4, GlueX / Hall D Detector Electron Beam from CEBAF Lead Glass Detector Solenoid Coherent Bremsstrahlung Photon Beam Tracking Target Cerenkov Counter Time of Flight Barrel Calorimeter Note that tagger is 80 m upstream of detector

Elton S. Smith PaNic02, Sep 30 – Oct 4, Output: /- 3 MeV Output: 173 +/- 11 MeV Double-blind M. C. exercise Statistics shown here correspond to a few days of running. Mass Input: 1600 MeV Width Input: 170 MeV Finding an Exotic Wave An exotic wave (J PC = 1 -+ ) was generated at level of 2.5 % with 7 other waves. Events were smeared, accepted, passed to PWA fitter.

Elton S. Smith PaNic02, Sep 30 – Oct 4, Detector Designed to do Partial Wave Analysis Double blind studies of 3  final states  p n    X  Linear Polarization m  [GeV/c 2 ]  GJ a2a2   

Elton S. Smith PaNic02, Sep 30 – Oct 4, dimensional view of the Nucleon Deep Exclusive Scattering

Elton S. Smith PaNic02, Sep 30 – Oct 4, Generalized Parton Distributions and the GPD’s unify the description of inclusive and exclusive processes, connecting directly to the “normal” parton distributions: GPD’s provide access to fundamental quantities such as the quark orbital angular momentum that have not been accessible

Elton S. Smith PaNic02, Sep 30 – Oct 4, Limiting Cases for GPDs Ordinary Parton Distributions ( , t,  → 0) H 0 (x,0) = q(x) unpolarized H 0 (x,0) =  q(x) polarized ~ Nucleon Form Factors (Sum Rules) Dirac Pauli Axial vector Pseudoscalar EHEH ~, ~,, x P (x-  ) P P PP 2  t

Elton S. Smith PaNic02, Sep 30 – Oct 4, GPDs Contain Much More Information than DIS Quark distribution q(x) qq distribution Antiquark distribution q(x) DIS only measures a cut at  =0

Elton S. Smith PaNic02, Sep 30 – Oct 4, Measuring the GPD’s  Key experimental capabilities include : ─ CW (100% duty factor) electron beams (permits fully exclusive reactions) ─ modern detectors (permit exclusive reactions at high luminosity) ─ adequate energy (~10 GeV to access the valence quark regime)  Measurements of the GPD’s are now feasible

Elton S. Smith PaNic02, Sep 30 – Oct 4, Interpretation of the GPD’s Analogy with form factors Parton Distribution ↔ GPD’s Ref. Burkardt CM ii biq Rfrombdistanceaatxfractionmomentum withquarksofdensitypartonaisbxfwhere rxRtorelativemeasuredb bxfebdqxH             ),( 2  Charge ↔ Form Factor      M rm Rtorelativemeasuredr rerdqF ii cm rqi     )()( 3 

Elton S. Smith PaNic02, Sep 30 – Oct 4, dim picture Elastic ScatteringDeep InelasticDeep Exclusive from Belitsky and Mueller

Elton S. Smith PaNic02, Sep 30 – Oct 4, Meson Production as a Filter  Use quantum numbers of meson to select appropriate combinations of parton distributions in nucleon. Pseudo-scalars (polarized)  0 :  u v - ½  d v  :  u v - ½  d v + 2  s v Vector Mesons (unpolarized)  L 0 : u + u + ½ (d + d); g  L 0 : u + u - ½ (d + d); g  L 0 : s + s; g pp  (z)  j  (y)  (z)  i  (y) **

Elton S. Smith PaNic02, Sep 30 – Oct 4, Program to determine GPD’s ( ,  ) e  e N  e ( ,  ) K Other Channels ~, ~,, ~, ~, EHEHpe EHen EHep          Eenpe EHEHeppe ~ H ~ ~, ~,,        eNpe   ↳

Elton S. Smith PaNic02, Sep 30 – Oct 4, Deep Virtual Compton Scattering: A Window on Quark Correlations  DIS corresponds exactly to the imaginary part of the Deep Compton Scattering amplitude  Add determination of the final state (by exclusive reactions such as DVCS) and we can (finally!) probe nucleon quark structure and correlations at the amplitude level DIS is limited by the fact that it can only measure longitudinal distributions averaged over all quarks in the nucleon

Elton S. Smith PaNic02, Sep 30 – Oct 4, CLAS Collaboration PRL 87, (2001) Measure interference between DVCS-BH e e’ p p GPD’s  Q 2 = 5.4 GeV 2 x = t = 0.3 GeV 2 CLAS experiment E 0 = 11 GeV P e = 80% L = cm -2 s -1 Run time: 2000 hrs DVCS Single-Spin Asymmetry

Elton S. Smith PaNic02, Sep 30 – Oct 4, Hard Meson Electroproduction (  o )  Physics issue: map out GPD’s (need to isolate  L )  Technique: determine  L from  →  decay angle distribution  CLAS at 11 GeV 400 hrs at L = cm -2 s -1 e’ p  GPD’s e p  L ~ Q -6  T ~ Q -8

Elton S. Smith PaNic02, Sep 30 – Oct 4, Valence Quark Structure of the Nucleon Parton Distributions at large x

Elton S. Smith PaNic02, Sep 30 – Oct 4, Enhanced Access to the DIS Regime  12 GeV will access the valence quark regime for x > 0.3  where constituent quark properties are not masked by the sea quarks

Elton S. Smith PaNic02, Sep 30 – Oct 4, Predictions for large x Bj Nucleon ModelF 2 n /F 2 p d/uA1nA1n A1pA1p SU(6)2/31/205/9 Valence Quark1/4011 pQCD3/71/511 Proton Wavefunction (Spin and Flavor Symmetric) )( 3 2 )( 3 1 )( 3 1 )( 18 1 )( 2 1     SS SSS uud d udu u up

Elton S. Smith PaNic02, Sep 30 – Oct 4, Valence Quark Distribution  Physics issue: ─ compare behavior of u and d quarks as x Bj → 1  Experimental problem: ─ extract information from comparison of hydrogen and deuterium data ─ need to correct for nuclear effects in D  Solution for CEBAF upgrade: ─ compare DIS off 3 He and 3 H (nuclear effects ~ same) pQCD Valence QuarkSU(6)

Elton S. Smith PaNic02, Sep 30 – Oct 4,  Study of spin structure functions has been limited to the low-x region  JLab at 12 GeV with its high luminosity is a prime facility for measurements at large x The Neutron Spin Asymmetry A 1 n Jlab E ( 3 He) preliminary

Elton S. Smith PaNic02, Sep 30 – Oct 4, Flavor Decomposition: (e,e’  + )/(e,e’  - )

Elton S. Smith PaNic02, Sep 30 – Oct 4, GeV Upgrade Project Status  Developed by CEBAF User Community in collaboration with JLab  Nuclear Science Advisory Committee, NSAC ─ plan presented during last 5-year Long Range Plan ─ recommended by NSAC for new construction  Plan presented to Department of Energy ─ presently waiting for CD-0 (determination of ‘mission need’)  Detailed report is being prepared to be reviewed by Jlab PAC in January  Construction ─ construction start expected in FY2007 (October 2006) ─ 3 year construction project

Elton S. Smith PaNic02, Sep 30 – Oct 4,

Elton S. Smith PaNic02, Sep 30 – Oct 4, CLAS++ Detector Forward TOF Preshower EC Forward EC Forward Cerenkov Forward DC Inner Cerenkov Inner Calorimeter Torus Cold Ring Central Detector

Elton S. Smith PaNic02, Sep 30 – Oct 4, SHMS - HMS Spectrometers After Upgrade Max. Central Momentum 11 GeV/c 9 GeV/c Min. Scattering Angle 5.5 deg 10 deg Momentum Resolution.15% -.2% Solid Angle 2.1 msr 4.4 msr Momentum Acceptance 20% 40% Target Length Acceptance 50 cm Opening Angle with HMS 25 deg16 deg Configuration QQ(DQ) Bend Angle 18.4 deg

Elton S. Smith PaNic02, Sep 30 – Oct 4, Physics Program at 12 GeV Gluonic Excitations Valence Structure of the Nucleon 3-dim view of the Nucleon Exciting Compelling In view of recent progress in lattice calculations Timely

Elton S. Smith PaNic02, Sep 30 – Oct 4, Ion Source RFQ Injector DTL CCL IR Beam Dump Snake Solenoids Snake 5 GeV CEBAF with Energy Recovery 5 GeV electrons 100 GeV light ions Electron-Light Ion Collider Layout 100 MV cryomodules Lia Merminga Luminosity = cm -2 s -1