H. Avakian, Baryons, Dec 10 1 Transverse spin physics at CLAS and CLAS12 H.Avakian (JLab) BARYONS’10 Dec. 7-11, 2010, Osaka, Japan

H. Avakian, Baryons, Dec 10 2Outline Physics motivation k T -effects with unpolarized and longitudinally polarized target data Physics with transversely polarized hadrons and quarks Future studies of 3D PDFs at CLAS at 6 GeV Transverse structure & CLAS12 How spin-orbit correlations are related to the orbital momentum, longitudinal structure and nuclear effects?

H. Avakian, Baryons, Dec Structure of the Nucleon d2kTd2kT W p u (k,r T ) “Mother” distributions (Wigner, GTMDs,..) d2rTd2rT d2kTd2kT PDFs q(x),  q(x)… d2rTd2rT Spin and longitudinal momentum correlations with k T and r T lead to observable effects in exclusive and semi- inclusive processes TMD PDFs q(x,k T ),  q(x,k T )… GPD/IPDs H(x,r T ), H~(x,r T )…

Nucleon TMDs Transverse Momentum Distributions (TMDs) of partons describe the distribution of quarks and gluons in a nucleon with respect to x and the intrinsic transverse momentum k T carried by the quarks

H. Avakian, Baryons, Dec SIDIS: partonic cross sections kTkT P T = p ┴ +z k T p┴p┴ Ji,Ma,Yuan Phys.Rev.D71:034005,2005 Use azimuthal moments in SIDIS to study spin-orbit correlations.

H. Avakian, Baryons, Dec CLAS configurations  e  ep→e’  X  Polarizations:  Beam: ~80%  NH3 proton 80%,ND3 ~30%  HD (H-75%,D-25%) 1)Polarized NH3/ND3 (no IC, ~5 days) 2)Unpolarized H (with IC ~ 60 days) 3)Polarized NH3/ND3 with IC 60 days 10% of data on carbon 4)Polarized HD-Ice (no IC, 25 days) Unpolarized, longitudinally and transversely polarized targets Unpolarized and longitudinally polarized targets 0.05 K 0.6 K 1 K 4K4K Inner Calorimeter HD-Ice

H. Avakian, Baryons, Dec Scattering of 5.7 GeV electrons off polarized proton and deuteron targets SIDIS with JLab 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 Large P T range and full coverage in azimuthal angle  crucial for studies

H. Avakian, Baryons, Dec 10 8 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 arXiv:

H. Avakian, Baryons, Dec Quark distributions at large k T : lattice Higher probability to find a quark anti-aligned with proton spin at large k T and b T B.Musch et al arXiv: B.Pasquini et al Significant correlations of spin and transverse degrees of freedom predicted

H. Avakian, Baryons, Dec Quark distributions at large k T : lattice B.Musch et al arXiv:  u/u JMR model q Dq M R, R=s,a Sign change of  u/u consistent between lattice and diquark model

H. Avakian, Baryons, Dec A 1 A 1 P T -dependence CLAS data suggests that width of g 1 is less than the width of f 1 Anselmino Collins Lattice New CLAS data would allow multidimensional binning to study k T -dependence for fixed x PTPT PTPT arXiv:

H. Avakian, Baryons, Dec ~10% of E data 12 Longitudinal Target SSA measurements at CLAS p 1 sin  +p 2 sin2  0.12<x<0.48 Q 2 >1.1 GeV 2 P T <1 GeV ep→e’  X W 2 >4 GeV 2 0.4<z<0.7 M X >1.4 GeV y<0.85 p 1 = 0.059±0.010 p 2 =-0.041±0.010 p 1 =-0.042±0.015 p 2 =-0.052±0.016 p 1 =0.082±0.018 p 2 =0.012±0.019 CLAS-2009 (E05-113) CLAS PRELIMINARY CLAS-2000 Data consistent with negative sin2  for  +

H. Avakian, Baryons, Dec Kotzinian-Mulders Asymmetries B.Musch arXiv: B.Pasquini et al, arXiv: HERMES CLAS (5 days) Worm gear TMDs are unique (no analog in GPDs)

H. Avakian, Baryons, Dec Beam SSA: A LU from JLab 0.5<z<0.8 Beam SSA from hadronization (Collins effect) by Schweitzer et al. Photon Sivers Effect Afanasev & Carlson, Metz & Schlegel Beam SSA from initial distribution (Boer-Mulders TMD) F.Yuan using h 1 ┴ from MIT bag model No leading twist contributions: provides access to quark-gluon correlations

H. Avakian, Baryons, Dec x PTPT hh S=S= y HT function related to force on the quark. M.Burkardt (2008) Chiral odd HT-distribution How can we separate the HT contributions? Compare single hadron and dihadron SSAs Only 2 terms with common unknown HT G~ term! M.Radici

H. Avakian, Baryons, Dec 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 CLAS transversely polarized HD-Ice target HD-Ice target vs std nuclear targets

H. Avakian, Baryons, Dec Collins SSAs CLAS with a transversely polarized target will allow measurements of transverse spin distributions and constrain Collins fragmentation function Anselmino et al CLAS E (2011)

H. Avakian, Baryons, Dec 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

H. Avakian, Baryons, Dec CLAS12 LTCC FTOF PCAL EC HTCC Lumi = cm -2 s -1 High beam polarization 80% High target polarization 85% NH 3 (30 days) ND 3 (50 days) Wide detector and physics acceptance allow studies of both current and target fragmentation regions using semi inclusive and exclusive processes Solenoid 5T DC R1, R2, R3 LTCC HTCC FTOF PCAL EC CLAS12 L = cm -2 s -1 Primary goal of experiments: study of the 3D structure of the nucleon

H. Avakian, Baryons, Dec CLAS12: Kinematical coverage Large P T, Q 2 accessible with CLAS12 are important for studies of the 3D structure and separation of HT contributions. Q 2 >1GeV 2 W 2 >4 GeV 2 (10) y<0.85 M X >2GeV SIDIS kinematics eXeX

H. Avakian, Baryons, Dec E : E : Pion SIDIS E : E : Kaon SIDIS E : E : Pion SIDIS E : E : Kaon SIDIS LOI : LOI : Pion SIDIS LOI : LOI : Kaon SIDIS PAC approved experiments & LoI N q U L T  Complete program of TMDs studies for pions and kaons  Kaon measurements crucial for a better understanding of the TMDs “kaon puzzle”  Kaon SIDIS program requires an upgrade of the CLAS12 detector PID  RICH detector to replace LTCC (talk by P. Rossi) Project under development TMDs 12 GeV in Hall B

H. Avakian, Baryons, Dec Longitudinally polarized target: helicity distributions High precision measurements of double spin asymmetries will significantly improve the knowledge of helicity distributions Wide range in P T of hadrons would allow measurements of transverse momentum dependence of partonic distributions in the valence region

H. Avakian, Baryons, Dec CLAS12: CLAS12 will provide pretzelosity measurement in the valence region for Kaons and pions. B. PasquiniB. Pasquini et al. arXiv: Exciting relation: (in bag & spectator model) helicity - transversity = ‘measure’ of relativistic effects In models (bag, diquark) pretzelosity defines the OAM She, Zhu & Ma, Phys. Rev. D 79 (2009)

H. Avakian, Baryons, Dec Nonperturbative TMD Perturbative region P T -dependence of beam SSA  sin  LU(UL) ~F LU(UL) ~ 1/Q (Twist-3) 1/P T Check of the higher twist nature of observed SSA critical SSA test transition from non-perturbative to perturbative region 1/Q

H. Avakian, Baryons, Dec Summary CLAS longitudinally polarized NH3 and ND3 target data provides superior sample of events allowing detailed studies of single and double spin asymmetries using multidimensional bins Measurements of spin and azimuthal asymmetries with unpolarized, longitudinally polarized and transversely polarized targets in semi-inclusive processes at JLab : Measure TMDs of partons in the valence region Provide detailed info on partonic spin-orbit correlations Study quark-gluon correlations (HT) Study nuclear modification of 3D PDFs CLAS12 will significantly increase the luminosity, kinematical coverage and particle identification capabilities of CLAS6

H. Avakian, Baryons, Dec Support slides….

H. Avakian, Baryons, Dec Some analysis topics for latest polarized proton and deuteron target data SIDIS with JLab at 6 GeV Inclusive g1p Inclusive g1d DVCS A UL on proton DVCS A UL on neutron DVCS A LL SIDIS A UL & A LL for pions on proton SIDIS A UL & A LL for pions on deuteron SIDIS A UL & A LL for kaons and   on proton Modifications of azimuthal moments in nuclei Large acceptance of CLAS allows simultaneous measurements of hard exclusive and semi-inclusive reactions providing complementary information on the complex nucleon structure.

M.Osipenko 28 H. Avakian, Baryons, Dec 10

29 Some questions to address What is the shape of k T -distributions? Are there correlations between transverse space and momentum distributions? Can k T -distributions be flavor dependent? Are k T -distributions the same for different spin orientations? How spin-orbit correlations change the momentum distributions? What is the fraction of k T -generated in FSI? How quark-gluon correlations affect transverse momentum and space distributions? How nuclear medium changes k T and b T -distributions? How gluons and sea are distributed in k T

H. Avakian, Baryons, Dec 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 EMC

Nucleon TMDs Transverse Momentum Distributions (TMDs) of partons describe the distribution of quarks and gluons in a nucleon with respect to x and the intrinsic transverse momentum k T carried by the quarks

H. Avakian, Baryons, Dec HDice polarized targets of solid hydrogen,  +HD (E06-101); e+HD (E08-021) polarize to frozen-spin state at 12 mK, 15 tesla in new HDice Lab transfer to CLAS In-Beam-Cryostat renovated Lab in Test Lab Annex installing polarizing equip assembling Oxford dilution fridge - training SC magnet new NMR electronics under test - optimize H  D spin transfer fabricating CLAS target cells HD purity analysis  prep time - chromatography & Raman scat    HDice Lab Hall B

33 Single hadron production in hard scattering Measurements in different kinematical regions for nucleon and nucleus provide complementary information on the complex nucleon structure. x F - momentum in the CM frame x F >0 (current fragmentation) x F <0 (target fragmentation) h h Target fragmentationCurrent fragmentation Fracture Functions xFxF M 0 1 h h TMD GPD k T -dependent PDFsGeneralized PDFs PDF h FF DA exclusivesemi-inclusive semi-exclusive

H. Avakian, Baryons, Dec Collins fragmentation & higher twists s T (q×P T )↔ H 1 ┴ sin(2  h ) CC y x SS hh PTPT  S =  +  h x PTPT hh S=S= y HT function related to force on the quark. M.Burkardt (2008)  C  =  h  S’ D(z,P T )=D 1 (z,P T )+H 1 ┴(z,P T ) sin(  C ) Interactions make difference

H. Avakian, Baryons, Dec HDice In-Beam Cryostat for CLAS HDice Transfer Cryostat designed for both  (Start Counter) and e - (mini-Torus) ASME code review nearly complete under construction 0.05 K 0.6 K 1 K1 K 4 K4 K HDice IBC-CLAS loading    HDice In-Beam Cryostat

H. Avakian, Baryons, Dec cos  moment in A LL -P T -dependence P T -dependence of cos  moment of double spin asymmetry is most sensitive to k T - distributions of quarks with spin orientations along and opposite to the proton spin. hep-ph/  0 2 =0.25GeV 2  D 2 =0.2GeV 2 CLAS PRELIMINARY

H. Avakian, Baryons, Dec Exclusive     and     from CLAS e p e p  π + π - e - p  e - n  + π+π0π+π0 ++ Measurements of ratios      ,       … J u,J d Gluon exchange at low W suppressed (x-sections for   and   comparable) Quark exchange, which dominates, can be considered as part of SIDIS