Research Perspectives at Jefferson Lab Kees de Jager
Research Perspectives at Jefferson Lab Kees de Jager Jefferson Lab Duality 05 Workshop LFN Frascati June 6 -8, 2005 Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 1
CEBAF @ 12 Ge. V, WHY? • • Gluonic Excitations and the Origin of Confinement Developing a Unified Description of Hadron Structure Þ Valence Quark Structure and Parton Distributions Þ Form Factors – Constraints on the GPDs Þ The Generalized Parton Distributions (GPDs) as Accessed via Deep(ly) Exclusive Reactions Þ Other Topics in Hadron Structure • • The Physics of Nuclei Þ The Quark Structure of Nuclei (resolving the EMC effect) Þ The Short-Range Behavior of the N-N Interaction and Its QCD Basis Þ Quark propagation through Nuclear Matter (hadronization) Symmetry Tests in Nuclear Physics Þ Precision Tests of the Standard Model Þ Spontaneous Symmetry Breaking Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 2
Enhanced Kinematical Access to the DIS Regime 12 Ge. V will access the regime (x > 0. 3), where valence quarks dominate Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 3
with enough luminosity to reach the high-Q 2, high-x region Counts/hour/ (100 Me. V)2 (100 Me. V 2) for L=1035 cm-2 sec-1 Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 4
Gluonic Excitations from Alex Dzierba Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 5
Gluonic Excitations and the Origin of Confinement The quarks in a meson are sources of a color electric flux which is trapped in a flux tube connecting the quarks. The formation of the flux tube is related to the self-interaction of gluons via their color charge. From G. Bali linear potential • Flux tubes result in a linear confining potential • Do flux tubes apply to light-quark systems? • Very little is known about gluonic (or flux-tube) excitations Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 6
Photons Preferred for Flux Tube Excitations Normal mesons: JPC = 0 -+ 1+- 2 -+ First excited state of flux tube has JPC=1+- or 1 -+ combined with S=1 for quarks results in JPC = 0 -+ 0+- 1 -+ 2+- exotic (mass ~ 1. 7 – 2. 3 Ge. V) Photons couple to exotic mesons via g VM transition (same spin configuration) Double-blind Monte Carlo simulation: 2 % exotic signal clearly visible Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 7
Strategy for Exotic Meson Search • Use photons to produce meson final states with a mass up to 2. 5 Ge. V – tagged photon beam with 8 – 9 Ge. V – linear polarization to constrain production mechanism • Use large acceptance detector – hermetic coverage for charged and neutral particles – typical hadronic final states: f 1 h KKh b 1 w – high data-acquisition rate • Perform partial-wave analysis – identify quantum numbers as a function of mass – check consistency of results in different decay modes Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 8 KK
Hadron Structure from Zein-Eddine Meziani and Volkert Burkert Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 9
Unpolarized Neutron to Proton ratio • In the nlargep x region (x>0. 5) the • Impact: • determine valence d quark momentum ratio F 2 /F 2 is not well determined due to the lack of a free neutron target distribution • extract helicity dependent quark distributions through inclusive DIS • high x and Q 2 background in high energy particle searches. • construct moments of structure functions Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 10
Unpolarized Neutron to Proton ratio DIS from A=3 nuclei Spectator tagging • • • Nearly free neutron target by tagging • low-momentum proton from deuteron at backward angles Small p (70 -100 Me. V/c) Minimize on-shell extrapolation (neutron only 7 Me. V off-shell) Backward angles ( pq> 110 o) Minimize final-state interactions Mirror symmetry of A=3 nuclei Extract F 2 n/F 2 p from ratio of 3 He/3 H structure functions and superratio R R = ratio of ”EMC ratios” for 3 He and 3 H can be calculated to within 1% • Most systematic and theoretical uncertainties cancel Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 11
Unpolarized Neutron to Proton Ratio Hall B 11 Ge. V with CLAS 12 Hall C 11 Ge. V with HMS Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 12
Inclusive measurements of asymmetries A 1 n at 11 Ge. V A 1 p at 11 Ge. V W>1. 2 Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 13
Flavor decomposition At RHIC with W production Ee = 11 Ge. V polarized NH 3 and 3 He Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 14
Flavor decomposition: polarized sea . . Predictions: Instantons (c. QSM): JLab @11 Ge. V • First data from HERMES 0 Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 15
Quark-gluon correlations and g 2 Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 16
g 2 at JLab with 11 Ge. V Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 17
Moments of Structure Functions target mass correction term dynamical twist-3 matrix element dynamical twist-4 matrix element • Both d 2 and f 2 are required to determine the color polarizabilities • To extract f 2, d 2 needs to be determined first Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 18
Color “Polarizabilities” Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 19
d 2 with 11 Ge. V at JLab Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 20
Charged Pion Electromagnetic Form Factor Where does the dynamics of the q-q interaction make a transition from the strong QCD (confinement) to the p. QCD regime? • It will occur earliest in the simplest systems the pion form factor F (Q 2) provides a good starting system to determine the relevant distance scale experimentally • In asymptotic region, F 8 s ƒ Q-2 HMS+SHMS (11 Ge. V) projection Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 21
Proton Charge Form Factor Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 22
CLAS 12 : Neutron GMn With 12 Ge. V Upgrade e. D ep Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 23 en(ps) e +n
GPDs & Deeply Virtual Exclusive Processes “handbag” mechanism Deeply Virtual Compton Scattering (DVCS) hard vertices x+ x- g x – longitudinal quark momentum fraction – longitudinal momentum transfer x –t – Fourier conjugate to transverse impact parameter t H(x, , t), E(x, , t), . . x= x. B 2 -x. B Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 24
Kinematics Coverage of the 12 Ge. V Upgrade overlap with other experiments unique to JLab High x. B only reachable with high luminosity H 1, ZEUS e d a r g p U b a JL Upgraded JLab has complementary & unique capabilities Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 25
DVCS SSA Measures phase and amplitude directly DVCS and Bethe-Heitler are coherent can measure amplitude AND phase DVCS at 11 Ge. V can cleanly test correlations in nucleon structure (data shown – 2000 hours) Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 26
DVCS/BH Transverse Target Asymmetry E = 11 Ge. V Sample kinematics Q 2=2. 2 Ge. V 2, x. B = 0. 25, -t = 0. 5 Ge. V 2 Transversely polarized target Ds ~ sinf. Im{k 1(F 2 H – F 1 E) +…}df AUTx Target polarized in scattering plane AUTy Target polarized perpendicular to scattering plane § Asymmetry highly sensitive to the u-quark contributions to proton spin Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 27
Exclusive 0 production on transverse target T AUT = - 2 (Im(AB*))/ 0 |A| (1 - - |B| ( +t/4 m 2) - Re(AB AUT + A ~ 2 Hu + Hd B ~ 2 Eu + Ed A ~ Hu - Hd B ~ Eu - E d Asymmetry depends linearly on the GPD E, which enters Ji’s sum rule. CLAS 12 K. Goeke, M. V. Polyakov, M. Vanderhaeghen, 2001 x. B Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 28
Physics of Nuclei from Will Brooks Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 29
Unpacking the EMC effect • With 12 Ge. V, we have a variety of tools to unravel the EMC effect: Parton model ideas are valid over fairly wide kinematic range High luminosity High polarization • New experiments, including several major programs: Precision study of A-dependence; x>1; valence vs. sea g 1 A(x) “Polarized EMC effect” – influence of nucleus on spin Flavor-tagged polarized structure functions u. A(x. A) and d. A(x. A) x dependence of axial-vector current in nuclei (can study via parity violation) Nucleon-tagged structure functions from 2 H and 3 He with recoil detector Study x-dependence of exclusive channels on light nuclei, sum up to EMC Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 30
Hadronization How do energetic quarks transform into hadrons? How quickly does it happen? What are the mechanisms? Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 31
Expected Results on Hadronization 12 12 Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 32
Parity Violation from Krishna Kumar Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 33
Electron-Quark Phenomenology A V V A C 1 u and C 1 d will be determined to high precision by other experiments C 2 u and C 2 d are small and poorly known: can be accessed in PV DIS New physics such as compositeness, new gauge bosons: Deviations to C 2 u and C 2 d might be fractionally large Proposed JLab upgrade experiment will make it possible to improve knowledge of 2 C 2 u-C 2 d by more than a factor of 20 Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 34
Parity Violating Electron DIS e- e. Z* N * X fi(x) are quark distribution functions For an isoscalar target like 2 H, structure functions largely cancel in the ratio: Provided Q 2 >> 1 Ge. V 2 and W 2 >> 4 Ge. V 2 and x ~ 0. 2 - 0. 4 Must measure APV to fractional accuracy better than 1% • 11 Ge. V at high luminosity makes very high precision feasible • JLab is uniquely capable of providing beam of extraordinary stability • Systematic control of normalization errors being developed at 6 Ge. V Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 35
2 H Experiment at 11 Ge. V E’ = 5. 0 Ge. V ± 10% Ibeam = 90 µA lab = 12. 5 o 60 cm LD 2 target • Use both HMS and SHMS to increase solid angle • ~2 MHz DIS rate, π/e ~ 2 -3 x. Bj ~ 0. 235, Q 2 ~ 2. 6 Ge. V 2, W 2 ~ 9. 5 Ge. V 2 Advantages over 6 Ge. V: • Higher Q 2, W 2, f(y) • Lower rate, better π/e • Better systematics: 0. 7% APV = 217 ppm 1000 hours (APV)=0. 65 ppm (2 C 2 u-C 2 d)=± 0. 0086± 0. 0080 Theory: +0. 0986 PDG (2004): -0. 08 ± 0. 24 Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 36
Physics Implications (2 C 2 u-C 2 d)=0. 012 (sin 2 W)=0. 0009 Unique, unmatched constraints on axial-vector quark couplings: Complementary to LHC direct searches Examples: • 1 Te. V extra gauge bosons (model dependent) • Te. V scale leptoquarks with specific chiral couplings Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 37
PV DIS and Nucleon Structure • • • Analysis assumed control of QCD uncertainties Higher twist effects Charge Symmetry Violation (CSV) d/u at high x Nu. Te. V provides perspective Result is 3 from theory prediction Raised very interesting nucleon structure issues: cannot be addressed by Nu. Te. V JLab at 11 Ge. V offers new opportunities PV DIS can address issues directly Luminosity and kinematic coverage Outstanding opportunities for new discoveries Provide confidence in electroweak measurement Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 38
Search for CSV in PV DIS • u-d mass difference • electromagnetic effects • Direct observation of parton-level CSV would be very exciting • Important implications for high-energy collider pdfs • Could explain significant portion of the Nu. Te. V anomaly For APV in electron-2 H DIS: Sensitivity will be further enhanced if u+d falls off more rapidly than u- d as x -> 1 Strategy: • measure or constrain higher twist effects at x ~ 0. 5 -0. 6 • precision measurement of APV at x ~ 0. 7 to search for CSV Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 39
APV in DIS on 1 H + small corrections • Allows d/u measurement on a single proton • Vector quark current (electron is axial-vector) • Determine that higher twist is under control • Determine standard model agreement at low x • Obtain high precision at high x Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 40
d/u at High x Deuteron analysis has nuclear corrections APV for the proton has no such corrections Must simultaneously constrain higher twist effects The challenge is to get statistical and systematic errors ~ 2% Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 41
Large Acceptance: Concept • CW 90 µA at 11 Ge. V • 40 -60 cm liquid H 2 and D 2 targets • Luminosity > 1038/cm 2/s JLab Upgrade • Need high rates at high x • For the first time: sufficient rates to make precision PV DIS measurements • solid angle > 200 msr • count at 100 k. Hz • online pion rejection of 102 to 103 Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 42
12 11 6 Ge. V CEBAF Add new hall Upgrade magnets and power supplies CHL-2 Enhance equipment in existing halls Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 43
Hall A w/ 2. 2, 4. 4, 6. 6, 8. 8 and 11 Ge. V Beam • Retain High Resolution Spectrometer (HRS) pair for the continuation of research in which energy resolution comparable to nuclear level spacing is essential • Use the hall infrastructure to support specialized large-installation experiments Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 44
CLAS 12 - Acceptance for DVCS Occupancy of DVCS events ep epg Q 2 > 2. 5 Ge. V 2 E = 11 Ge. V Kinematic Limit Central Detector For small t, protons recoil at large polar angles 60 50 40 30 Forward Detector 20 10 Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy 70 Duality 05, Frascati, June 8, 2005, 45
CLAS 12 Preshower EC (not visible) Forward EC Low Threshold Cerenkov Counter (LTCC) Forward Drift Chambers Forward TOF High Threshold Cerenkov (HTCC) New Torus Coils Central Detector Beamline Inner EC Reused CLAS element (not visible) Coil EC Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 46
Hall C: The SHMS and HMS Super. HMS SOS Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 47
Glue. X Detector Barrel Calorimeter Lead Glass Detector Solenoid Coherent Bremsstrahlung Photon Beam Time of Flight Note that tagger is 80 m upstream of detector Tracking Target Electron beam from CEBAF Cerenkov Counter Event rate to processor farm: 10 k. Hz and later 180 k. Hz corresponding to data rates of 50 and 900 Mbytes/sec, respectively Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 48
DOE Critical Decisions CD DOE Meaning Implications of CD Approval Time CD-0 Approve Mission Need Formal CDR work begins using DOE funds R&D for CDR begins PED funds can be requested Acquisition plan developed Serious search for non-DOE/NP funding April 2004 CD-1 Approve Preliminary Baseline Range Lehman review of CDR and approval PED funds can be spent ~August 2005 CD-2 Approve Second Lehman review to establish budget, Performance Baseline schedule and performance Long-lead procurements begin Request construction funding 2006/7 ? ? CD-3 Approve Start of Construction begins in earnest 2008/9 ? ? CD-4 Approve Start of Operations Science begins! 2013 ? ? Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 49
Status of 12 Ge. V project • The 12 Ge. V JLab upgrade, a formal recommendation of the NSAC Long Range Plan, will permit a major step forward in the study of “strong” QCD and hadron structure • Substantial progress has been made toward refining the experimental program and equipment designs • DOE has provided a “mission need statement” (CD-0 approval) • A recent DOE review of the science program was highly supportive • JLab is in the process of obtaining CD-1 approval • International involvement is essential to move this exciting project forward rapidly Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 50
Highlights of the 12 Ge. V Program Exploration of QCD in the Nonperturbative Regime: • Existence and properties of exotic mesons Detailed study of hadronic structure • Revolutionize Our Knowledge of Spin and Flavor Dependence of Valence PDFs • Revolutionize Our Knowledge of Distribution of Charge and Current in the Nucleon • Totally New View of Hadron (and Nuclear) Structure: • GPDs, Determination of the quark angular momentum Nuclear Structure in Terms of QCD • Spin and flavor dependence of EMC Effect • Study quark propagation through nuclear matter Parity Violation in Deep Inelastic Scattering • Factor 20 improvement in (2 C 2 u-C 2 d) • Sensitive tests of Charge Symmetry Violation & valence region Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U. S. Department Of Energy Duality 05, Frascati, June 8, 2005, 51
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