Physics Program with 12 GeV JLab J. P. Chen, Jefferson Lab EIC Workshop, APS-DNP/JPS Joint Meeting, 10/13/2009  Introduction and Overview  Nucleon Structure - Spin-Flavor Structure in Valance Region  Nucleon Structure - Generalized Parton Distributions  Nucleon Structure - Transverse Momentum Dependent Distributions  Nucleon Structure - Form Factors  Parity Violation Electron Scattering - Low Energy Test of Standard Model  Nuclear Physics: Hadronization, Short-Range Correlations, Few-Body  Exotic Meson Search: Gluon Excitations Acknowledgement: Some slides “borrowed” from colleague’s talks

QCD and Nucleon Structure A major challenge in fundamental physics: Understand QCD in all regions, including strong (confinement) region Nucleon = u u d + sea + gluons Structure mostly determined by strong interaction Mass, charge, magnetic moment, spin, axial charge, tensor charge Decomposition of each of the above fundamental quantities Mass: ~1 GeV, but u/d quark mass only a few MeV each! Momentum: total quarks only carry ~ 50% Spin: ½, total quarks contribution only ~30% Spin Sum Rule Tensor charge Transverse sum rule? Multi-dimensional structure and distributions Confinement -- QCD vacuum: gluon field and sea

Jefferson Lab Experimental Halls HallA: two HRS’ Hall B:CLAS Hall C: HMS+SOS 6 GeV polarized CW electron beam Pol=85%, I=180  A Luminosity ~ Polarized ~ Will be upgraded to 12 GeV by ~ 2014

Hall A polarized 3 He target longitudinal, transverse and vertical Luminosity = P(in-beam) = 65% Effective polarized neutron I=15 uA Hall B/C Polarized p/d target Polarized NH 3 /ND 3 targets Luminosity ~ (Hall C), ~ (Hall B) In-beam average polarization 70-90% for p, 30-40% for d

CHL-2 Upgrade magnets and power supplies Enhance equipment in existing halls 6 GeV CEBAF Add new hall

Experimental Halls (new) Hall D: linear polarized photon beam, Selonoid detetcor ­ GluoX collaboration: exotic meson spectroscopy gluon-quark hybrid, confinement Hall B: CLAS12 ­ GPDs, TMDs, … Hall C: Super HMS + existing HMS ­ Form factors, structure functions, … Hall A: Dedicated devices + existing spectrometers ­ Super BigBite, Solenoid, Moller Spectrometer ­ SIDIS, PVDIS, …

Overview of Physics Program Gluonic Excitations and the Origin of Confinement Nucleon Structure Quark spin-flavor structure in valence region Deep Exclusive Reactions (DVCS, DVMP) to study GPDs SIDIS to measure Transversity and TMDs Form Factors – Constraints on the GPDs Symmetry Tests Parity violation to test Standard Model and precision study of hadronic physics The Physics of Nuclei Medium Effects: Hadronization, EMC effects Short-Range Correlations Few-Body

12 GeV Upgrade Kinematical Reach Reach a broad DIS region Decisive inclusive DIS measurements at high-x Precision Deep Exclusive Reactions (e.x. DVCS) to study GPDs Precision SIDIS for transversity and TMDs Parity Violating DIS to test Standard Model and precision study of hadronic physics

Structure Functions at High x Valence Quark Distributions

Hall A 11 GeV with HRS BONUS at Hall B 11 GeV with CLAS12 F 2 n /F 2 p  d/u ratio at high-x

Hall B CLAS, Phys.Lett. B641 (2006) 11 Hall A E99-117, PRL 92, (2004) PRC 70, (2004) JLab 6 GeV Results on A 1 at high x SU(6) pQCD

Inclusive Hall A and B and Semi-Inclusive Hermes BBS BBS+OAM F. Yuan, H. Avakian, S. Brodsky, and A. Deur, arXiv: Polarized Parton Distribution at Large x pQCD with Quark Orbital Angular Momentum

A 1 p at 11 GeV Projections for JLab at 11 GeV pQCD SU(6)

 u and  d at JLab 11 GeV Polarized Sea GeV Flavor Decomposition with SIDIS

Generalized Parton Distributions 3-d Quark-Gluon Structure of the Nucleon

Beyond form factors and quark distributions – Generalized Parton Distributions (GPDs) Proton form factors, transverse charge & current densities X. Ji, D. Mueller, A. Radyushkin, … M. Burkardt, … Interpretation in impact parameter space Structure functions, quark longitudinal momentum & helicity distributions Correlated quark momentum and helicity distributions in transverse space - GPDs

GPDs & Deeply Virtual Exclusive Processes x Deeply Virtual Compton Scattering (DVCS) t x+  x-  H(x, , t ), E(x, , t ),.. hard vertices  – longitudinal momentum transfer x – longitudinal quark momentum fraction – t – Fourier conjugate to transverse impact parameter  “handbag” mechanism x B 2-x B  =

Twist 2 contribution Twist 3 contribution strongly suppressed Hall A E Demonstrated Handbag Dominance at Modest Q 2 The Twist-2 term can be extracted accurately from the cross-section difference Dominance of twist-2  handbag dominance  DVCS interpretation straightforward

Deeply Virtual Exclusive Processes - Kinematics Coverage of the 12 GeV Upgrade JLab Upgrade Upgraded JLab has complementary & unique capabilities unique to JLab overlap with other experiments High x B only reachable with high luminosity H1, ZEUS

DVCS/BH- Beam Asymmetry With large acceptance, measure large Q 2, x B, t ranges simultaneously. A(Q 2,x B,t)  (Q 2,x B,t)  (Q 2,x B,t) E e = 11 GeV A LU

CLAS12 – L/T Separation ep ep        LL TT x B = t = GeV 2 Other bins measured concurrently Projections for 11 GeV (sample kinematics)

Single Spin Asymmetry in Semi-inclusive DIS Transverse Momentum Dependent Distributions

“Leading-Twist” TMD Quark Distributions Quark Nucleon Unpol. Long. Trans. Unpol. Long. Trans.

JLab 6 GeV experiment (E06-010/06-011) SSA in SIDIS n ↑ (e,e′π +/- ) on a Transversely Polarized 3 He Target Collins Sivers First neutron ( 3 He) measurement Completed data taking in 2/2009 Spokespersons: X. Jiang (Los Alamos) J.P. Chen (JLab) E. Cisbani (INFN) H. Gao (Duke) J.-C. Peng (UIUC) PhD Students: K. Allada (UKy) C. Dutta (UKy) J. Huang (MIT) J. Katich (W&M) X. Qian (Duke) Y. Wang (UIUC) Y. Zhang (Lanzhou)

3 He target 12 GeV: Solenoid detector for SIDIS and PVDIS GEMs Gas Cerenkov Calorimeter GEMs

Projection vs P T and x for  + (60 days) For one z bin ( ) Will obtain 4 z bins ( ) Also  - at same time With upgraded PID for K+ and K-

3-D Projections for Collins and Sivers Asymmetry (  + )

Parity Violating Electron Scattering Test Standard Model and Precision Study of Hadron Structure

Parity Violating DIS C 1u and C 1d will be determined to high precision by Q weak, APV Cs C 2u and C 2d are small and poorly known: one combination can be accessed in PV DIS New physics such as compositeness, leptoquarks: Deviations to C 2u and C 2d might be fractionally large AV V A Moller PV is insensitive to the C ij

PVDIS with SoLID High Luminosity on LH 2 & LD 2 Better than 1% errors for small bins x-range Moderate running times

Physics Implications Examples: 1 TeV extra gauge bosons (model dependent) TeV scale leptoquarks with specific chiral couplings Unique, unmatched constraints on axial-vector quark couplings: Complementary to LHC direct searches  (2C 2u -C 2d )=0.012  (sin 2  W )=0.0009

PV DIS and Nucleon Structure PVDIS provide precision study of hadron structure: –Higher twist effects –Charge Symmetry Violation (CSV) –d/u at high x JLab at 11 GeV offers new opportunities –PV DIS can address issues directly Luminosity and kinematic coverage Outstanding opportunities for new discoveries Provide confidence in electroweak measurement

Parity Violating Moller Scattering Q W e modified sin 2  W runs with Q 2 Semileptonic processes have theoretical uncertainties E158 established running, probing vector boson loops JLab measurement would have impact on discrepancy between leptonic and hadronic Z-pole measurements  (sin 2  W ) ~ Comparable to single collider measurements

Hadronization in Nuclear SIDIS Quark Propagation Through Nuclei

Nuclear Deep Inelastic Scattering and Hadronization  We can learn about hadronization distance scales and reaction mechanisms from semi-inclusive nuclear DIS  Nucleus acts as a spatial filter for outgoing hadronization products Initial focus on properties of leading hadron; correlations with subleading hadrons and soft protons also of interest.

 (GeV)  z Observables – Hadronic Multiplicity Ratio ( ≈ medium-modified fragmentation function) In general, h = , K, , p,.… Significant dependence of R on Must Must measure multi-variable dependence for stringent model tests! = , = = , =

Each point is differential in Q 2,, z, and A; all are acquired simultaneously 12 GeV Anticipated Data

Summary 12 GeV JLab with high luminosity (10 39 unpol., pol.) and large acceptance will lead us to a new precision frontier Provide precision data on multi-dimension nucleon structure and a deep understanding of strong interaction: Spin-flavor structure in the valence region Generalized Parton Distributions with DVCS and limited DVMP Transverse Spin and TMDs with SIDIS Parity violating electron scattering provide precision low-energy tests of standard model and a precision tool to study hadronic physics Precision Study of hadronization and nuclei medium effects Other important physics opportunities: GlueX, Form Factors, Short-range Correlations, Few-Body, J/  …

Strong Interaction and QCD A major challenge in fundamental physics: Understand QCD in all regions, including strong interaction (confinement) region Strong interaction, running coupling ~1 -- QCD: accepted theory for strong interaction -- asymptotic freedom (2004 Nobel) perturbation calculation works at high energy -- interaction significant at intermediate energy quark-gluon correlations -- interaction strong at low energy (nucleon size) confinement, chiral symmetry breaking E ss

New Hall D, Enhanced Existing Halls A, B & C 9 GeV tagged polarized photons and a 4  hermetic detector D Super High Momentum Spectrometer (SHMS) at high luminosity and forward angles C CLAS upgraded to higher (10 35 cm -2 s -1 ) luminosity and coverage B Retain HRS Pair for continuation of research in which resolution comparable to nuclear level spacing is essential. Use Hall to stage “one-of-a-kind” specialized experiments requiring unique apparatus. A

Why Are PDFs at High x Important? Valence quark dominance: simpler picture -- direct comparison with nucleon structure models SU(6) symmetry, broken SU(6), diquark x  1 region amenable to pQCD analysis -- hadron helicity conservation? Clean connection with QCD, via lattice moments Input for search for physics beyond the Standard Model at high energy collider -- evolution: high x at low Q 2  low x at high Q 2 -- small uncertainties amplified -- example: HERA ‘anomaly’ (1998) Input to nuclear, high energy physics calculations

Proton Neutron World Data on A 1

Color “Polarizabilities”

E “g2p” SANE “d2n” just completed in Hall A 6 GeV Experiments Sane: just completed in Hall C “g2p” in Hall A, 2011 projected Jlab 6 GeV Results on d 2

Color Polarizability d 2 n with JLab 12 GeV Projections with 12 GeV experiments  Improved Lattice Calculation (QCDSF, hep-lat/ )

Link to DIS and Elastic Form Factors ),,( ~, ~,,txEHEH qqqq      J G =  1 1 )0,,()0,,( xExHxdxJ qqq Quark angular momentum (Ji’s sum rule) X. Ji, Phy.Rev.Lett.78,610(1997) DIS at  =t=0 )(),()0,0,( ~ )( ()0,0,( xqxqx H xq xqxH q q    Form factors (sum rules)  )(),,( ~, )(),,( ~ ) Dirac f.f.(),,(, 1 1, tGtxEdxtGtxH tF1F1 txH qP q qA q q q          ) Pauli f.f.(),,( 1 tF2F2 txEdx q q     

Access GPDs through DVCS x-section & asymmetries Accessed by cross sections Accessed by beam/target spin asymmetry t=0 Quark distribution q(x) -q(-x) DIS measures at  =0

DVCS interpreted in pQCD at Q 2 > 1 GeV 2 A LU E=5.75 GeV = 2.0GeV 2 = 0.3 = 0.3GeV 2 CLAS preliminary  [ rad ] Pioneering DVCS experiments First GPD analyses of HERA/CLAS/HERMES data in LO/NLO consistent with  ~ A. Freund (2003), A. Belitsky et al. (2003) Full GPD analysis needs high statistics and broad coverage twist-3twist-2 A UL =  sin  +  sin2  twist-3 contributions are small

CLAS12 - DVCS/BH Target Asymmetry e p ep  = 2.0GeV 2 = 0.2 = 0.25GeV 2 CLAS preliminary E=5.75 GeV A UL Longitudinally polarized target  ~sin  Im{F 1 H +  (F 1 +F 2 ) H... }d  ~ E = 11 GeV L = 2x10 35 cm -2 s -1 T = 1000 hrs  Q 2 = 1GeV 2  x = 0.05

DVCS DVMP GPDs – Flavor separation hard vertices hard gluon Photons cannot separate u/d quark contributions. long. only M =  select H, E, for u/d flavors M = , K select H, E

transverse polarized target 3D Images of the Proton’s Quark Content M. Burkardt PRD 66, (2002) b - Impact parameter T u(x,b ) T d(x,b ) T u X (x,b ) T d X (x,b ) T HuHu EuEu Needs:HdHd EdEd quark flavor polarization Accessed in Single Spin Asymmetries.

Transversity and TMDs Three twist-2 quark distributions (integrated over P ┴ ) : Momentum distributions: q(x,Q 2 ) = q ↑ (x) + q ↓ (x) Longitudinal spin distributions: Δq(x,Q 2 ) = q ↑ (x) - q ↓ (x) Transversity distributions: δq(x,Q 2 ) = q ┴ (x) - q ┬ (x) Tensor charge: integral of transversity over x TMDs (without integrating over P T ), 8 distributions + fragmentation functions: Distribution functions depends on x, k ┴ and Q 2 : δq, f 1T ┴ (x,k ┴,Q 2 ), … Fragmentation functions depends on z, p ┴ and Q 2 : D, H 1 (x,p ┴,Q 2 ) Measured asymmetries depends on x, z, P ┴ and Q 2 : Collins, Sivers, … (k ┴, p ┴ and P ┴ are related)

A UT sin(  ) from transv. pol. H target Simultaneous fit to sin(  +  s ) and sin(  -  s ) `Collins‘ moments Non-zero Collins asymmetry Assume  q(x) from model, then H 1 _unfav ~ -H 1 _fav Need independent H 1 (BELLE) `Sivers‘ moments Sivers function nonzero (  + )  orbital angular momentum of quarks Regular flagmentation functions

PKU-RBRC Workshop on Transverse Spin Physics, June 30, 2008 F. Bradamante Collins asymmetry – proton data comparison with M. Anselmino et al. predictions Franco Bradamante Transverse2008, Beijing

PKU-RBRC Workshop on Transverse Spin Physics, June 30, 2008 F. Bradamante Sivers asymmetry – proton data comparison with the most recent predictions from M. Anselmino et al. Franco Bradamante Transverse2008, Beijing

Current Status Large single spin asymmetry in pp->  X Collins Asymmetries - sizable for proton (HERMES and COMPASS ) large at high x, large for  -  - and  has opposite sign  unfavored Collins fragmentation as large as favored (opposite sign)? - consistent with 0 for deuteron (COMPASS) Sivers Asymmetries - non-zero for  + from proton (HERMES), consistent with zero (COMPASS)? - consistent with zero for  - from proton and for all channels from deuteron - large for K + ? Very active theoretical and experimental study RHIC-spin, JLab (Hall A 6 GeV, CLAS12, HallA/C 12 GeV), Belle, FAIR (PAX) Global Fits/models by Anselmino et al., Yuan et al. and … Solenoid with polarized 3 He at JLab 12 GeV Unprecedented precision with high luminosity and large acceptance

Precision Study of Transversity and TMDs From exploration to precision study Transversity: fundamental PDFs, tensor charge TMDs provide 3-d structure information of the nucleon Laboratory to study QCD Learn about quark orbital angular momentum Multi-dimensional mapping of TMDs 3-d (x,z,P ┴ ) Q 2 dependence multi facilities, global effort Precision  high statistics high luminosity and large acceptance

Discussion Unprecedented precision 3-d mapping of SSA Collins, Sivers and other TMDs  +,  - and K +, K - Study factorization with x and z-dependences Study P T dependence Combining with CLAS12 proton and world data extract transversity and fragmentation functions for both u and d quarks determine tensor charge study TMDs for both valence and sea quarks study quark orbital angular momentum Combining with world data, especially data from high energy facilities study Q 2 evolution Global efforts (experimentalists and theorists), global analysis much better understanding of 3-d nucleon structure and QCD

The couplings depend on electroweak physics as well as on the weak vector and axial-vector hadronic current Both new physics at high energy scales as well as interesting features of hadronic structure come into play A program with many targets and a broad kinematic range can untangle the physics (g A e g V T +  g V e g A T ) PV Electron Scattering on Hadron

PAC34 Statistical Errors (%) vs Kinematics 4 months at 11 GeV 2 months at 6.6 GeV Error bar σ A /A (%) shown at center of bins in Q 2, x For SOLID Spectrometer

12 GeV PVDIS Sensitivity: C 1 and C 2 Plots Cs PVDIS Qweak PVDIS World’s data Precision Data 6 GeV

CSV Theory and Data MRST PDF global with fit of CSV Martin, Roberts, Stirling, Thorne [Eur Phys J C35, 325 (04)]: Analytic calculation similar to global fit Londergan & Thomas, (also B. Ma)

Search for CSV in PV DIS Sensitivity will be further enhanced if u+d falls off more rapidly than  u-  d as x  1 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 NuTeV anomaly For A PV in electron- 2 H DIS:

Sensitivity with PVDIS

Study Higher-Twist in PVDIS Twist-2 (mostly) cancel in asymmetry Twist-4 is (basically) leading twist Clean access twist-4 effect: free from twist-2 order dependence Study quark-quark correlations

Coherent Program of PVDIS Study Measure A D in NARROW bins of x, Q 2 with 0.5% precision Cover broad Q 2 range for x in [0.3,0.6] to constrain HT Search for CSV with x dependence of A D at high x Use x>0.4, high Q 2, and to measure a combination of the C iq ’s Strategy: requires precise kinematics and broad range xyQ2Q2 New Physicsnoyesno CSVyesno Higher Twistyesnoyes Fit data to: C(x)=β HT /(1-x) 3

PVDIS on the Proton: d/u at High x Deuteron analysis has large nuclear corrections (Yellow) A PV for the proton has no such corrections (complementary to BONUS) The challenge is to get statistical and systematic errors ~ 2% 3-month run

Fixed Target Møller Scattering Purely leptonic reaction Weak charge of the electron : Q W e ~ 1 - 4sin 2  W - Maximal at 90 o in COM (E’=E lab /2) - Highest possible E lab with good P 2 I - Moderate E lab with LARGE P 2 I Figure of Merit rises linearly with E lab SLAC E158 Jlab at 12 GeV Unprecedented opportunity: The best precision at Q 2 <<M Z 2 with the least theoretical uncertainty until the advent of a linear collider or a neutrino factory

Design for 12 GeV E’: 3-6 GeV  lab = 0.53 o o A PV = 40 ppb I beam = 90 µA 150 cm LH 2 target Beam systematics: steady progress (E158 Run III: 3 ppb) Focus alleviates backgrounds: ep  ep(  ), ep  eX(  ) Radiation-hard integrating detector Normalization requirements similar to other planned experiments Cryogenics, density fluctuations and electronics will push the state- of-the-art Toroidal spectrometer ring focus 4000 hours  (A PV )=0.58 ppb

New Physics Reach  ee ~ 25 TeV JLab Møller  ee ~ 15 TeV LEP200 LHC Complementary; 1-2 TeV reach New Contact Interactions Does Supersymmetry (SUSY) provide a candidate for dark matter? Lightest SUSY particle (neutralino) is stable if baryon (B) and lepton (L) numbers are conserved However, B and L need not be conserved in SUSY, leading to neutralino decay (RPV) Examples: Kurylov, Ramsey-Musolf, Su 95% C.L. JLab 12 GeV Møller

Two Possible Hadronization Mechanisms RG GY String model Gluon bremsstrahlung model