IWHSS09, Apr 1 1 Harut Avakian (JLab) Mainz, April 1, 2009 SIDIS results from JLAB

IWHSS09, Apr 1 2 Outline Describe the complex nucleon structure in terms of partonic degrees of freedom of QCD Physics motivation –Transverse Momentum Distributions (TMDs) of quarks and spin- azimuthal asymmetries in semi-inclusive DIS SIDIS results from JLab at 6 GeV –Tests of the applicability of the partonic picture –Studies of spin-orbit correlations with CLAS Measurements of TMDs at 6 GeV –Longitudinally polarized proton target measurements (E05-113) –Transversely polarized 3 He (E06-010/011) and proton targets (E08-015) Summary

IWHSS09, Apr 1 3 z sin2  moment of the cross section for unpolarized beam and longitudinal target U unpolarized L long.polarized T trans.polarized SIDIS kinematical plane and observables Transverse spin effects are observable as correlations of transverse spin and transverse momentum of quarks.

IWHSS09, Apr 1 4 Structure of the Nucleon GPDs/IPDs d2kTd2kT d2kTd2kT TMD PDFs f 1 u (x,k T ),.. h 1 u (x,k T )  Gauge invariant definition (Belitsky,Ji,Yuan 2003)  Universality of k T -dependent PDFs (Collins,Metz 2003)  Factorization for small k T. (Ji,Ma,Yuan 2005) W p u (k,r T ) “Mother” Wigner distributions d2rTd2rT PDFs f 1 u (x),.. h 1 u (x) quark polarization

IWHSS09, Apr 1 5 CLAS at JLAB Electron beam energy 6 GeV Lumi ~10 34 cm -2 sec -1

IWHSS09, Apr 1 6 Scattering of 5.7 GeV electrons off unpolarized and polarized proton and deuteron targets SIDIS with CLAS at 6 GeV  DIS kinematics, Q 2 >1 GeV 2, W 2 >4 GeV 2, y<0.85  0.4>z>0.7, M X 2 >2 GeV 2 2 eXeX  e  1)Polarized NH3/ND3 (~5 days) 2)Polarized H days (2001/2005)

IWHSS09, Apr 1 7  multiplicities in SIDIS ep→e’  X  +/- multiplicities at large z diverge from SIDIS predictions  0 multiplicities less affected by higher twists 0.4<z<0.7 kinematical range, where higher twists are expected to be small DSS (Q 2 =2.5GeV 2 ) DSS (Q 2 =25GeV 2 ) M.Aghasyan Hall-C

IWHSS09, Apr 1 8 R pd- Both ratios agree with PDF models for z 1.4 GeV) Tests of partonic picture with  ratios 6 GeV R pd+

IWHSS09, Apr 1 9 A 1 P T -dependence in SIDIS M.Anselmino et al hep-ph/  + A LL can be explained in terms of broader k T distributions for f 1 compared to g 1  0 2 =0.25GeV 2  D 2 =0.2GeV 2 In perturbative limit predicted to be constant Como-2005 constituent quark model ( Pasquini et al ).

IWHSS09, Apr 1 10 BBS/LSS no OAM BBS/LSS with OAM Quark longitudinal polarization JMR model q Dq M R, R=s,a For given x the sign of the polarization is changing at large k T Effect of the orbital motion on the q- may be significant (H.A.,S.Brodsky, A.Deur,F.Yuan 2007)  u/u (dipole formfactor), J.Ellis, D-S.Hwang, A.Kotzinian

IWHSS09, Apr 1 11 A 1 P T -dependence in SIDIS M.Anselmino et al hep-ph/  + A 1 suggests broader k T distributions for f 1 than for g 1  - A 1 may require non-Gaussian k T -dependence for different helicities and/or flavors  0 2 =0.25GeV 2  D 2 =0.2GeV 2 0.4<z<0.7

IWHSS09, Apr 1 12 Extracting widths from A 1 Assuming the widths of f 1 /g 1 x,z and flavor independent Anselmino et al Collins et al Fits to unpolarized data

IWHSS09, Apr 1 13 A 1 P T -dependence CLAS data suggests that width of g 1 is less than the width of f 1 Anselmino Collins

IWHSS09, Apr 1 14 Collins Effect: azimuthal modulation of the fragmentation function D(z,P T )=D 1 (z,P T )+H 1 ┴(z,P T ) sin(  h  S’ ) spin of quark flips wrt y-axis  S’ =  -  S sin(  h  S ) CC SS STST y x hh PTPT sTsT  S’ CC F UT ∞h 1 H 1 ┴ s T (q×P T )↔ H 1 ┴ sin(2  h ) CC x PTPT hh S=hS=h y y x SS hh PTPT  S =  +  h x PTPT hh S=S= y hadronizing quark Intial quark polarization

IWHSS09, Apr 1 15 SIDIS (  *p->  X) x-section at leading twist Measure Boer-Mulders distribution functions and probe the polarized fragmentation function Measurements from different experiments consistent TMD PDFs

IWHSS09, Apr 1 16 Kotzinian-Mulders asymmetry Data indicate that spin-orbit correlations with long.pol. target may be significant Provide measurement of SSA for all 3 pions, extract the RSMT TMD (Ralston-Soper (1979), Mulders-Tangerman (1995) curves,  QSM from Efremov et al Transversely polarized quarks in the longitudinally polarized nucleon More data needed to clarify the situation with negative pions

IWHSS09, Apr 1 17 What comes next Hall-A Transversely polarized 3 He target measurement (E06-010/011) Hall-B Longitudinally polarized proton (NH 3 ) target measurement (E05-113) Hall-B Transversely polarized proton target measurement (E08-015) Currently running Calibrating September 2011 Sivers asymmetry Collins asymmetry with transverse (neutron) target Correlations of transverse and longitudinal momenta (P T - dependences) in A LL Collins asymmetry with longitudinally polarized (proton) target Exclusive asymmetries as background Sivers asymmetry Collins asymmetry with transverse proton target Shape of proton studies Exclusive asymmetries as background Fixed bins in x/Q 2 Wide kinematical coverage, multiple hadronic states

IWHSS09, Apr 1 18 Cell: Astral Cell: Maureen e e’e’   HRS L BigBite 16 o 30 o Polarized 3 He Target Target Single-Spin Asymmetry in Semi-Inclusive n ↑ (e, e’  +/- ) p t ~ 65% (proposal 42%) First measurement of the neutron Collins and Sivers asymmetries in SIDIS. High density polarized 3 He target. Run in Hall A from 10/24/08-2/5/ shift workers, 7 Ph.D. students. Reaction on a Transversely Polarized 3 He Target E06-010:

IWHSS09, Apr 1 19 Experimental Setup Inner Calorimeter (424 PbWO 4 crystals) to detect high energy photons at forward lab angles. Polarized target (NH3/ND3) 13 o 50 o IC 1)Polarized NH3 with IC 60 days 2)Polarized HD-Ice (no IC, 25 days)

IWHSS09, Apr 1 20 A LL P T -dependence in SIDIS M.Anselmino et al hep-ph/ study the P T -dependence for different quark helicities and flavors for bins in x,  2 (x) flavor decomposition in P T -bins.  0 2 =0.25GeV 2  D 2 =0.2GeV 2 0.4<z<0.7 E05-113

IWHSS09, Apr 1 21 Kotzinian-Mulders asymmetry Provide measurement of SSA for all 3 pions, extract the RSMT TMD (Ralston- Soper (1979), Mulders-Tangerman (1995) Study Collins fragmentation with longitudinally polarized target curves,  QSM from Efremov et al 60 days of CLAS L= cm -2 s -1 Transversely polarized quarks in the longitudinally polarized nucleon E05-113

IWHSS09, Apr 1 22 Pros 1.Small field (∫Bdl~ Tm) 2.Small dilution (fraction of events from polarized material) 3.Less radiation length 4.Less nuclear background (no nuclear attenuation) 5.Wider acceptance much better FOM, especially for deuteron Cons 1.HD target is highly complex and there is a need for redundancy due to the very long polarizing times (months). 2.Need to demonstrate that the target can remain polarized for long periods with an electron beam with currents of order of 1-2 nA 3.Additional shielding of Moller electrons necessary (use minitorus) CLAS transversely polarized HD-Ice target Heat extraction is accomplished with thin aluminum wires running through the target (can operate at T~ mK) HD-Ice target at ~2nA ~ NH3 at 5 nA HD-Ice target vs std nuclear targets

IWHSS09, Apr 1 23 Collins SSAs CLAS with a transversely polarized target will allow measurements of transverse spin distributions and constrain Collins fragmentation function Anselmino et al (2007)Boffi et al (2009) helicity-transversity=pretzelosity CLAS E08-015

IWHSS09, Apr 1 24 Measurement of Sivers function and GPD-E DVCS Transverse asymmetry (function of momentum transfer to proton) is large and has strong sensitivity to GPD - E CLAS will provide a measurements of Sivers asymmetry at large x, where the effect is large and models unconstrained by previous measurements. Meissner, Metz & Goeke (2007) GPD-E=0 (DVCS) (SIDIS) CLAS E08-015

IWHSS09, Apr 1 25 Summary Significant azimuthal moments in pion production in SIDIS are measured using CLAS with longitudinally polarized target. Measurements of azimuthal dependences of double and single spin asymmetries indicate that correlations between spin and transverse motion of quarks may be significant. P T -dependences of the double and single-spin asymmetries provide important input for studies of flavor and helicity dependence of quark transverse momentum dependent distributions. Upcoming CLAS SIDIS experiments at 6 GeV will significantly improve the statistical precision of longitudinally polarized target data, and will provide new data on transversely polarized target

IWHSS09, Apr 1 26 Support slides….

IWHSS09, Apr 1 27

IWHSS09, Apr 1 28 Factorization studies R pd+ for any z, p t (if d and u have same p t dependence)! Simple LO picture in valence region: R pd- for any z, x!

IWHSS09, Apr 1 29 The CLAS Detector ~ 200 physicists 37 institutions large kinematical coverage high luminosity multi-particle final states charged particles: p>0.2 GeV/c 8 o <  <140 o  p /p~0.5% (  <30 o )  p /p~1-2%(  >30 o )   =1mrad   =4mrad

IWHSS09, Apr 1 30 Sivers effect: proton CLAS will provide a superior measurements of Sivers asymmetry at large x, where the effect is large and models unconstrained by previous measurements. Measure also asymmetries in target fragmentation region and for exclusive  channels (background) Vogelsang & Yuan Schweitzer et al CLAS E08-015

IWHSS09, Apr 1 31 Collins fragmentation: Longitudinally polarized target Study the Collins function of kaons Provides independent information on the RSMT TMD Kotzinian-Mulders Asymmetry protondeuteron Pasquini et al.

IWHSS09, Apr 1 32 Collins Effect: azimuthal modulation of the fragmentation function D(z,P T )=D 1 (z,P T )+H 1 ┴(z,P T ) sin(  h  S’ ) spin of quark flips wrt y-axis  S’ =  -  S sin(  h  S ) CC SS STST y x hh PTPT sTsT  S’ CC F UT ∞h 1 H 1 ┴ SS y x hh PTPT s T (p×k T )↔ h 1 ┴ F UU ∞h 1 ┴ H 1 ┴  S =  +  h s T (q×P T )↔ H 1 ┴ sin(2  h ) x CC PTPT hh S=hS=h y F UL ∞h 1L H 1 ┴ ┴ (s T k T )(pS L )↔ h 1L ┴ sin(  h +  S ) cos(2  h )

IWHSS09, Apr 1 33 JLab, Nov Hall A E06-010: Neutron (3He) Transversity Collins: transversity Sivers: Orbital Angular Momentum  First JLab transverse SSA measurement: running now to 2/09  First world neutron( 3 He) measurement

IWHSS09, Apr 1 34 Contributions to  in Double Polarized SIDIS TMDs Mulders et al

IWHSS09, Apr 1 35 Spin densities in transverse proton from Lattice (QCDSF/UKQCD) G.Miller/”pretzelosity” u-quark d-quark Spin of quark Boer-Mulders TMD

IWHSS09, Apr 1 36 SSA with unpolarized target quark polarization

IWHSS09, Apr 1 37 SSA with unpolarized target quark polarization

IWHSS09, Apr 1 38 SSA with long. polarized target quark polarization

IWHSS09, Apr 1 39 SSA with long. polarized target quark polarization

IWHSS09, Apr 1 40 CLAS: Fraction from baryonic decays in SIDIS Significant fraction from target fragmentation at pion momenta below 2 GeV

IWHSS09, Apr 1 41 Dilution factor in SIDIS Multiple scattering and attenuation in nuclear environment introduces additional P T -dependence for hadrons Fraction of events from polarized hydrogen in NH3 N u,N p -total counts from NH3 and carbon normalized by lumi  u,  p -total areal thickness of hydrogen (in NH3), and carbon target Cn=Nitr/Carbon ratio (~0.98) Diff. symbols for diff x-bins --

IWHSS09, Apr 1 42 Collins Effect: from asymmetries to distributions Combined analysis of Collins fragmentation asymmetries from SIDIS and e+e- (BELLE) would allow separation of transverse spin distributions (Anselmino et al., arXiv: ) need Brodsky & Yuan (2006) CLAS12

IWHSS09, Apr 1 43 Inclusive DIS BBS/LSS no OAM PDF measurements at large x provide additional information on OAM BBS/LSS with OAM

IWHSS09, Apr 1 44 Azimuthal Asymmetries in SIDIS Due to color coherence the configuration with gluon inside the quark cone is more probable Why < 0 ? Chay,Ellis,Stirling-1991   x  =180  =0

IWHSS09, Apr 1 45 HT and Semi-Exclusive Pion Production E. Berger, S. Brodsky 1979 (DY), E.Berger 1980, A.Brandenburg, V. Khoze, D. Muller 1995 A.Afanasev, C.Carlson, C. Wahlquist Phys.Lett.B398: ,1997 ++ Fragmentation  + 00 Azimuthal asymmetries with opposite sign from HT effects Effect may be suppressed for semi-exclusive  0 compared to  +/-