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Harut Avakian (JLab)

Studies of spin-orbit correlations in kaon electroproduction in DIS with longitudinally polarized hydrogen and deuterium targets. Harut Avakian (JLab). PAC34 JLab, January 27, 2009. Proposal PR12-09-09: Measure helicity distributions and the Collins fragmentation of kaons in SIDIS.

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Harut Avakian (JLab)

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  1. Studies of spin-orbit correlations in kaon electroproduction in DIS with longitudinally polarized hydrogen and deuterium targets Harut Avakian (JLab) PAC34 JLab, January 27, 2009 Proposal PR12-09-09: Measure helicity distributions and the Collins fragmentation of kaons in SIDIS Spokespersons: H. Avakian, E. Cisbani, K. Griffioen, K. Hafidi, P. Rossi PAC34, JLab, January 27

  2. The CLAS Collaboration PAC34, JLab, January 27

  3. Outline Transverse structure of the nucleon and correlations between longitudinal and transverse degrees of freedom. Introduction kT-effects with longitudinally polarized target Double spin asymmetries and kT-widths Single Spin Asymmetries and the Collins effect Projections for 12 GeV Summary PAC34, JLab, January 27

  4. SIDIS kinematical plane and observables z U unpolarized L long.polarized T trans.polarized sin2f moment of the cross section for unpolarized beam and longitudinal target Transverse spin effects are observable as correlations of transverse spin and transverse momentum of quarks. PAC34, JLab, January 27

  5. Target fragmentation Current fragmentation h h h M GPD PDF xF 0 1 -1 Fracture Functions kT-dependent PDFs Generalized PDFs Single hadron production in hard scattering xF>0 (current fragmentation) h xF<0 (target fragmentation) xF- momentum in the CM frame Wide kinematic coverage of large acceptance detectors allows studies of hadronization both in the target and current fragmentation regions PAC34, JLab, January 27

  6. Factorization of kT-dependent PDFs proven at low PT of hadrons (Ji et al) Twist-3 Transverse Momentum Dependent (TMD) Distributions Quark polarization • kT – leads to 3D description with 8PDFs Real and imaginary parts of the DL≠0 interference contributions Nucleon polarization PAC34, JLab, January 27

  7. constituent quark model (Pasquini et al). A1 PT-dependence in SIDIS m02=0.25GeV2 mD2=0.2GeV2 M.Anselmino et al hep-ph/0608048 Como-2005 In perturbative limit predicted to be constant p+ ALL can be explained in terms of broader kT distributions for f1 compared to g1 PAC34, JLab, January 27

  8. q Dq Du/u (dipole formfactor), J.Ellis, D-S.Hwang, A.Kotzinian Helicity distributions: Diquark model Jakob, Mulders, Rodrigues, Nucl. Phys. A 1997 JMR model MR, R=s,a For given xthesignof the polarization is changing at large kT Difference in q+=f1+g1 (quark aligned with proton spin) and q-=f1-g1 - (anti-aligned) kT-dependences may lead to observable effects PAC34, JLab, January 27

  9. A1 PT-dependence in SIDIS M.Anselmino et al hep-ph/0608048 0.4<z<0.7 m02=0.25GeV2 mD2=0.2GeV2 p+ A1 suggests broader kT distributions for f1 compared to g1 p- A1 may require non-Gaussian kT-dependence for different helicities and/or flavors PAC34, JLab, January 27

  10. - Collins asymmetry with longitudinally pol. proton First discussed by Kotzinian & Mulders (1996) Correlation between the transverse momentum and transverse spin of quarks in longitudinally polarized proton Clean observable: no Sivers type contributions, no twist-3 contributions Collins effect measurement with longitudinally pol. target provide access to the chiral-odd Ralston-Soper-Mulders-Tangerman (RSMT) distribution functions and probes the polarized fragmentation function PAC34, JLab, January 27

  11. Transversely polarized quarks in the long. polarized nucleon Brodsky & Yuan (2006) Light cone constituent quark model Pasquini,Cazzaniga & Boffi, Phys.Rev.D78:034025,2008 PAC34, JLab, January 27

  12. p↑p→hX BRAHMS Observed SSA show strong dependence on the final state hadron Collins SSA measurements e+e-→hhX +(u,d) K+(u,s) • K+ and + asymmetries consistent within error bars • K- and - asymmetries may have opposite sign PAC34, JLab, January 27

  13. L=1 Leading r opposite to leading p(into page) r production may produce an opposite sign AUT r hep-ph/9606390 Collins effect Sub-leading pion opposite to leading (into page) Simple string fragmentation (Artru model) Fraction of direct kaons may be significantly higher than the fraction of direct pions. LUND-MC PAC34, JLab, January 27

  14. The Collins function First calculation of the Collins function Bacchetta et al, Phys.Lett.B659:234-243,2008 HERMES/COMPASS/Belle spectator model Kaon Pion The Kaon Collins effect may be significant! PAC34, JLab, January 27

  15. 2/3 cm Proximity Gap 60/80 cm pad cathode coated with CsI film CLAS12 Wide detector and physics acceptance (current/target fragmentation) LTCC PCAL Lumi = 1035cm-2s-1 High beam polarization 80% High target polarization 85% NH3 (30 days) ND3 (50 days) EC HTCC FTOF ~4s K-p separation at ~5 GeV/c Replace 2 sectors of LTCC with a proximity RICH detector PAC34, JLab, January 27

  16. Kaon distributions in ep  e’KX SIDIS kinematics LUND-MC Q2>1GeV2 W2>4 GeV2(10) y<0.85 MX>2GeV forward High energy kaons are at small angles (q<30o) More kaons at small x PAC34, JLab, January 27

  17. ALL PT-dependence Anselmino et al, Phys.Rev.D74:074015,2006. proton deuteron GRSV-2000+Kretzer • Azimuthal asymmetry sensitive to the difference of widths in PDFs • Proton and deutron data provide a complete set required for the flavor decomposition PAC34, JLab, January 27

  18. Collins fragmentation: Longitudinally polarized target Kotzinian-Mulders Asymmetry proton deuteron Pasquini et al. • Study the Collins function of kaons • Provides independent information on the RSMT TMD PAC34, JLab, January 27

  19. Collins Effect: from asymmetries to distributions need Combined analysis of Collins fragmentation asymmetries from proton and deuteron may provide independent to e+e- (BELLE) Information on the underlying Collins function. PAC34, JLab, January 27

  20. Summary • Probe the Collins polarized fragmentation function of kaons • Provide complementary to pions info on the flavor and helicity dependence of quark transverse momentum distributions • Study the transverse polarization of quarks in the longitudinally polarized nucleon through measurements of the leading twist chiral-odd Ralston-Soper-Mulders-Tangerman distribution function. • Study higher twist effects and probe T-odd distributions in a wide range of Q2 • Latest experimental data indicate that spin-orbit correlations may be significant, leading to hadron flavor dependent observable spin and azimuthal asymmetries Beam request: 80 days of CLAS12@ 11 GeV with L=1035cm-2sec-1 (shared with E12-07-107) with longitudinally polarized NH3(30days) and ND3(50 days) with RICHupgrade Precision measurement of spin and azimuthal asymmetries (sin2f, cosf and sinf) in kaon production in DIS will allow us to: PAC34, JLab, January 27

  21. Support slides…. PAC34, JLab, January 27

  22. RICH 2/3 cm 60/80 cm Proximity Gap Replacement of LTCC with proximity focusing CsI Rich detector  good separation of p/K/p in the 2-5 GeV/c momentum range no impact on the baseline design of CLAS 12  minimum impact on spectrometer performaces pad cathode coated with CsI film Contalbrigo Marco PAC34 27 January 2009 A Rich detector for CLAS12 A Rich detector would strongly enhance the CLAS12 capabilities in particle identification and would open possibilities for new physics PAC34, JLab, January 27

  23. CLAS12 - Electromagnetic Background Low energy electromagnetic processes, especially Møller scattering of beam electrons off atomic electrons are the main contributor to the background load in an open large acceptance spectrometer such as CLAS12. The full event and background load has been measured with CLAS, e.g. for DVCS process at 5.7 GeV. The GEANT simulation reproduces hit occupancy on tracking chambers. We used the calibrated simulation code to extrapolate to 11 GeV and simulate the same process at higher luminosity for CLAS12 situation. This background was also studied in a full Geant4 simulation. PAC34, JLab, January 27

  24. CLAS12 Background at L=1035cm-2s-1, T = 150ns Electrons Photons Photons One Event One Event Shielding 5 T Magnetic Field and Shielding PAC34, JLab, January 27

  25. CLAS12 – Electromagnetic & Hadronic Rates (in MHz) Deposited Energy detector > 20 KeV RICH (5o-30o) (in 2 sectors) SVT (5o-35o) DC1 (5o-35o) Photons      Hadrons Photons      Hadrons Photons      Hadrons L1 31.3 2.5 L2 31.1 2.2 L3 24.6 2.2 1.7 3.1 32.3 0.85 Comment: For deposited energy of 20 KeV RICH would see about 35 hits in 1μsec window, randomly distributed over ~20 m2 and uncorrelated with track in DC. This is a very conservative estimate as for electrons to be knocked out from the RICH radiator > 500 KeV energy deposition is needed. PAC34, JLab, January 27

  26. Rpd- Both ratios agree with PDF models for z<0.7 (Mx>1.4 GeV) PAC34, JLab, January 27

  27. D-/D+ from Deuteron p+ to p- ratio Unfavored to favored ratio consistent with HERMES and EMC for z=0.55 PAC34, JLab, January 27

  28. p multiplicities in SIDIS ep→e’pX M.Aghasyan Hall-C DSS (Q2=2.5GeV2) DSS (Q2=25GeV2) p+/- multiplicities at large z diverge from SIDIS predictions p0 multiplicities less affected by higher twists 0.4<z<0.7 kinematical range, where higher twists are expected to be small PAC34, JLab, January 27

  29. Uncertainties PAC34, JLab, January 27

  30. Collins Effect: from asymmetries to distributions need Combined analysis of Collins fragmentation asymmetries from proton and deuteron may provide independent to e+e- (BELLE) Information on the underlying Collins function. PAC34, JLab, January 27

  31. Higher Twist SSAs and Quark-Gluon Correlations Discussed as main sources of SSA due to the Collins fragmentation Target sinf SSA (Bacchetta et al. 0405154) In jet SIDIS only contributions ~ D1 (Sivers type) Transversely polarized quarks With H1┴ (p0)≈0(or measured) Target and Beam SSA can be a valuable source of info on HT T-odd distribution functions PAC34, JLab, January 27

  32. SSA with unpolarized target quark polarization PAC34, JLab, January 27

  33. SSA with unpolarized target quark polarization PAC34, JLab, January 27

  34. SSA with long. polarized target quark polarization PAC34, JLab, January 27

  35. SSA with long. polarized target quark polarization PAC34, JLab, January 27

  36. CLAS: Fraction from baryonic decays in SIDIS Significant fraction from target fragmentation at pion momenta below 2 GeV PAC34, JLab, January 27

  37. Dilution factor in SIDIS Fraction of events from polarized hydrogen in NH3 Nu,Np -total counts from NH3 and carbon normalized by lumi ru, rp -total areal thickness of hydrogen (in NH3), and carbon target Cn=Nitr/Carbon ratio (~0.98) Diff. symbols for diff x-bins p- Multiple scattering and attenuation in nuclear environment introduces additional PT-dependence for hadrons PAC34, JLab, January 27

  38. CLAS12: Acceptance deformation due to incomplete azimuthal coverage Lab No significant effect seen from limited f coverage by RICH PAC34, JLab, January 27

  39. Inbendin/outbending configurations Different polarities increase the acceptance of positive and negative hadrons. PAC34, JLab, January 27

  40. Kinematic dependence of K/ ratios Critical for separation moment range 2<PK<5 and q<25 degree PAC34, JLab, January 27

  41. Kaon distributions in ep  e’KX Q2>1GeV2 W2>4 GeV2(10) y<0.85 MX>2GeV SIDIS kinematics High energy kaons are at small angles PAC34, JLab, January 27

  42. 4s K-p separation at 5 GeV/c 80 % kaon eff. with 1:1000 p rejection 95 % kaon eff. with 1:100 p rejection Already with 2 sectors gain of factor ~3 in the relevant z region of interest Contalbrigo Marco PAC34 27 January 2009 A Rich detector for CLAS12 MC simulation:  3 cm thick C5F12 radiator 80 cm CH4 proximity gap  1 cm pixel pad size  5 o-30 o radiator polar angle PAC34, JLab, January 27

  43. Transverse Momentum Dependent (TMD) Distributions Quark polarization • kT – leads to 3D description with 8PDFs Nucleon polarization Real and imaginary parts of the L=0 and L=1 interference contribution Related to transversity by Lorentz Invariant relations. In constituent quark model (Pasquini et al). PAC34, JLab, January 27

  44. Compare SIDIS experiments COMPASS/HERMES/CLAS cover different Q2 for the same x-range x=0.3 → Q2=~2 GeV2 (CLAS), ~7 GeV2(HERMES) ~30 GeV2(COMPASS) PAC34, JLab, January 27

  45. HERMES: Diffractive corrections to DIS PAC34, JLab, January 27

  46. Brodsky & Yuan (2006) Collins Effect: from asymmetries to distributions need CLAS12 Combined analysis of Collins fragmentation asymmetries from SIDIS and e+e- (BELLE) would allow separation of transverse spin distributions (Anselmino et al., arXiv:0707.1197 ) PAC34, JLab, January 27

  47. BBS/LSS with OAM JLab@12GeV: Inclusive DIS BBS/LSS no OAM PDF measurements at large x provide additional information on OAM PAC34, JLab, January 27

  48. qg interaction constant In color singlet Feynman diagrams every vertex loop The Large-Nc Behavior of the PDFs Use the large Nc limit of QCD to study TMD PDFs Introduced by ‘t Hooft in1974 Nc-power isospin P.Pobylitsa hep-ph/0301236 PAC34, JLab, January 27

  49. qg interaction constant In color singlet Feynman diagrams every vertex loop Change sign from + (SIDIS) to – (DY) Do not change sign (isoscalar) The Large-Nc limit of QCD to study TMD PDFs P.Pobylitsa hep-ph/0301236 Introduced by ‘t Hooft in1974 Nucleon mass M=O(Nc) I3 – nucleonisospin t3 – isospin Pauli matrice t1,t2 – isospin projection of quark fields (t3)uu =1, (t3)dd=-1 Large-Nc approach predicts signs and relative Nc power of TMDs, used in phenomenology. All others change sign u→d (isovector) PAC34, JLab, January 27

  50. GSIM12 Events for exclusive p+ production on proton (ep→e’p+n) Typical event PAC34, JLab, January 27

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