Spin Physics Program in Jefferson Lab's Hall C

Transcription

1 Spin Physics Program in Jefferson Lab's Hall C Oscar A. Rondón INPP - University of Virginia DIFFRACTION 014-8th International Workshop on Diffraction in High-Energy Physics Primošten, Croatia September 13, 014

2 Probing Nucleon Structure with Polarized Electromagnetic Scattering

3 Inelastic e-nucleon Scattering Inclusive EM scattering is described by hadronic and leptonic tensors Symmetries reduce hadronic tensor to four structure functions (SF's): Symmetric part: unpolarized W1, W Anti-symmetric part: spin-dependent G1, G A μν λ W = ϵμ νλ σ q σ σ σ M S G (ν,q )+ [ M ν S p S q ] G (ν,q )} { 1 e- e- Target fragments Current jet ( Inclusive scattering: undetected final state * hadronic structure does not contribute for Bjorken x > ~ 0.1 JLab's domain is best region for illuminating nucleon structure 3

4 Structure Functions in Inclusive DIS G1, G, W1 and W, contain all the information on nucleon structure that can be extracted from inclusive data In high energy DIS, g1 and g scale like F1 and F (up to log violations) lim Q, ν M W 1 (ν,q )=F 1 (x ) lim Q, ν ν W (ν, Q )=F (x) lim Q M ν G 1 (ν, Q )=g 1 ( x), ν lim Q M ν G (ν, Q )=g ( x), ν Bjorken x=q /( M ν) In the quark parton model g1 and F1 are also related to parton distribution functions - PDF's: 1 F 1 ( x)= e f (q f (x )+q f (x)) 1 g 1 ( x)= e f (q f (x ) q f (x)) 4

5 Virtual Compton Asymmetries The spin SF's are also related to virtual photon cross-sections and spin asymmetries (SA) the helicity of the virtual photon-nucleon system is 3/ or ½ for transverse photons, ½ for longitudinal ones SA A1 is defined in terms of the difference for 3/ and ½ helicity cross sections A represents the interference between initial transverse and final longitudinal amplitudes obeys Soffer-Teryaev bound A1= ) (1/ ) σ(3/ σ T T ) (1/ ) σ(3/ +σ T T 1 xm A1= ( g 1 γ g ) ; γ= F1 Q A = ) σ(1/ TL ) (1/ ) σ(3/ +σ T T A1 +1 σl R R= σ T γ γ A = ( g 1+ g )= g T F1 F1 5

6 Model Independent Extraction of Spin Structure Functions G1 and G can be separated by measuring cross section differences for opposite beam helicities with target spins parallel and transverse to the beam, N, = 4 E ' [ E cos E ' cos M G E E ' cos cos N 1 N G ] Q E cos =sin N sin cos cos N cos,, : final lepton angles transverse target spin N: comparable G1, G terms d d 4 E ' = E ' sin cos [ M G 1, Q E G, Q ] d de ' d de ' Q E G1 is twist- (plus corrections) G has both twist- and twist-3 contributions 6

7 Transverse Polarized Scattering: Unlocking Twist-3 Twist- and twist-3 operators contribute at same order in transverse polarized scattering twist-: handbag diagram twist-3: qgq correlations direct access to twist-3 via g: twist- interacting qgq, beyond asymptotically free partons, is first step to understanding confinement log Q αqcd twist-3 (twist- corrections) (Comments NPP 19, 39 (1990)) "Unique feature of spin-dependent scattering" (R. Jaffe) 7

8 g and gt Spin Structure Functions Experimentally measured quantities g T ( x)=g 1 ( x)+ g ( x)= 1 e q g qt ( x) q g T in terms of Transverse Momentum Dependent distributions [1] q k m h1 ( x) t g 1T ( x, k t ) g T ( x )= d k t + + g T ( x) x M x M twist-3 TMD quark mass term qgq interaction Applying twist- Wandzura-Wilczek approximation of g 1 g WW ( x )= g 1( x)+ x dy g ( y) y 1 Twist-3 for the nucleon (neglecting quark mass) g = [ ] 1 dy 1 e q g Tq x g qt ( y) g qt ( y )) ; g T =qg term, g T = Lorentz invariance [] ( y [1] hep-ph/ v1 [] JHEP 0911 (009) 093 8

9 Hall C Spin Experiments 9

10 Hall C Spin Structure Program Spin Structure Functions at 6 GeV: Inclusive measurements SSF's in the Nucleon Resonances - RSS (published) PRL 98, (007), PRL 105, (010), PRC 74, (006) Proton SSF at high Bjorken x - SANE (preliminary results) Precision Deuteron spin structure - g1d/f1d (Hall B eg1/dvcs) Semi-inclusive measurements Flavor Decomposition of Spin - SemiSANE (1 GeV) Real Polarized Photons: Polarized Compton Scattering - WACS (1 GeV) 10

11 RSS - Resonances Spin Structure Precision Measurement of the Nucleon Spin Structure Functions in the Region of the Nucleon Resonances TJNAF E U. Basel, Florida International U., Hampton U., U. Massachusetts, U. Maryland, Mississippi S. U., North Carolina A&T U., U. of N. C. at Wilmington, Norfolk S. U., Old Dominion U., S.U. New Orleans, U. of Tel-Aviv, TJNAF, U. of Virginia, Virginia P. I. & S.U., Yerevan Physics I. Spokesmen: Oscar A. Rondon (U. of Virginia) and Mark K. Jones (Jefferson Lab) Measure proton and deuteron spin asymmetries A1(W, Q²) and A(W, Q²) at Q² 1.3 GeV² and 0.8 W 1.91 GeV Goals: study W dependence of asymmetries, onset of polarized local duality, and twist-3 effects 11

12 SANE - Spin Asymmetries of the Nucleon Experiment (TJNAF E07-003) SANE Collaboration Argonne National Lab., Christopher Newport U., Florida International U., Hampton U., Jefferson Lab., U. of New Hampshire, Norfolk S. U., North Carolina A&T S. U., Mississippi S. U., Ohio U., IHEP - Protvino, U. of Regina, Rensselaer Polytechnic I., Rutgers U., Seoul National U., Southern U. New Orleans, Temple U., Tohoku U., U. of Virginia, Yerevan Physics I., Xavier U. Spokespersons: S. Choi (Seoul), M. Jones (JLab), Z-E. Meziani (Temple), O. A. Rondon (U. of Virginia) Measure the proton spin structure function g(x, Q²) and spin asymmetry A1 (x, Q²) for.5 Q² 6.5 GeV² and 0.3 x 0.8 Goal: Learn all we can about proton spin structure from an inclusive double polarization measurement 1

13 Layout in JLab's Hall C: RSS CEBAF South Linac High Momentum Spectrometer HMS Hall C 13

14 Layout in JLab's Hall C: SANE CEBAF South Linac Polarized Target [1] e- Beam <P> ~ 73% HMS Hall C [1] Big Electron Telescope Array ~ 190 msr; = ± 10 14

15 BETA with DIS electron simulation [] [3] [4] [5] Beam BigCal Pb glass Calorimeter [1] [1] BigCal Collaboration [] North Carolina A&T U. [3] Temple U B field: 80, 180 [4] Norfolk State U. and U. of Regina [5] UVA- JLab (W. Armstrong) 15

16 Polarized Target Dynamic Nuclear Polarized ammonia NH3, ND3, at 5T and 1K Proton <P> ~70% in beam Deuteron <P> ~0% in beam Proton luminosity ~1035 Hz cm- Target used in multiple experiments: SLAC: E143, E155, E155x (g) JLab: GEn98, GEn01, RSS, SANE Ammonia + LHe 16

17 Data 17

18 Hall C Spin Structure Program Experiment Detector Detected particle Scattering Type Beam Energy [GeV] Field Direction Target RSS HMS e- Inclusive inelastic & elastic , 90 NH3 ND3 C, LHe [1] SANE BETA e, 0 Inclusive inelastic 5.9, , 80 NH3 HMS e Inclusive inelastic 5.9, , 80 NH3 C, LHe [1] Inclusive elastic NH3 Coincidence elastic NH3 BETA - HMS e-p [1] Unpolarized, for dilution factor 18

19 BETA and HMS data 3 DIS Resonances RSS 5.75 GeV, 90o 180o SANE 5.9 GeV 80o 4.7 GeV 180o 5.9 GeV 80o 180o 4.7 GeV 80o 180o.5 Q [GeV ] W [GeV] Q x phase space of BETA's 80 data (SANE) cut on E' 1.3 GeV Central kinematics of HMS inclusive asymmetry data (RSS and SANE) 19

20 Measured Asymmetries A, A (RSS) - + N N ϵ Am = +C D ; ϵ = - + f Pb Pt C N N +N Am A phys = + Arc f rc N +,- = charge normalized, dead time corrected yields Pb, Pt = beam, target polarizations f = polarized dilution factor CN, CD = N polarization corrections Arc, frc= radiative corrections (Proton: PRL 98, (007)) 0

21 Measured Asymmetries A(80 ), A(180 ) + CN = N polarization corrections Arc, frc= radiative corrections Ab, fb = background corrections W [GeV] Pb, Pt = beam, target polarizations f = polarized dilution factor N +,- = charge normalized, dead time corrected yields E SAN inary m Preli 0.6 A A N N ϵ Am = ; ϵ= - + f Pb P t C N N +N 1 A m f b A b A phys= ( )+ Arc f rc 1 f b E SAN inary m Preli W [GeV] A =( A180 cos 80o + A 80 )/sin 80 o 1

22 Sample of Normalizations and corrections f Q²[GeV²] Pbeam E [GeV] W[GeV] fb MC Data Ptarget Run No.

23 Results 3

24 Spin Asymmetries A1 and A HMS single arm data in the resonances, Q² ~1.3 GeV² Model independent separation from measured asymmetries A1p E SAN RSS: PRL 98, (007) n limi Pre ary Ap in relim P E SAN ary W [GeV] W [GeV] (H-y. Kang) 4

25 Spin Asymmetries A1 and A HMS single arm data in the resonances, Q² ~1.8 GeV² Model independent separation from measured asymmetries ary n i m i l Pre A1p Ap y inar m i l Pre W [GeV] W [GeV] (H-y. Kang) 5

26 DIS Spin Asymmetry A1 A1p A 1p 01 APS ) inary m i l e (Pr BETA data - Statistical errors only p CLAS data of same W but different Q are merged in A1 (W) 6

27 g Spin Structure Functions PRL 105, (010) First world data for gp,d in the resonances Twist- gww computed using RSS fit to g1 point by point Clear difference between proton data and twist- part 7

28 g in DIS and Resonances BETA proton data DIS and resonances 0.3 < x < 0.8,.5 < Q < 6., E' 1.3 GeV (more data available down to 0.9 GeV) Twist- gww(4 GeV²) from PDF's SLAC E143, E155, E155x DIS data (Curves are twist- gww from PDF's) (W. Armstrong) 8

29 DIS Transverse Spin SF gt 0.8 gt 0.6 gt ary) n i m i (Prel 1 0 JLab twist- p SANE -3 GeV² SLAC.8-3 GeV² 3-4 GeV² 3-4 GeV² 4-5 GeV² 4-9 GeV² full gt 0.4 Bag Model (Jaffe & Ji) twist x SANE -3 GeV² SLAC.8-3 GeV² 3-4 GeV² 3-4 GeV² GeV² 4-9 GeV² gtp = F1 A / measures spin 0.7 Tangerman & Mulders hep-ph/ v1 Bag Model (1990's) distribution normal to * Data scaled.5 SANE gtp(x >.3) = 0.03±0.006 Model updates needed 9

30 Operator Product Expansion for Spin SF's RSS d twist-3 matrix elements OPE connects SF's CornwallNorton moments to twist-, twist-3 matrix elements an, dn x ranges Measured CN Nachtmann Full 0< x <1 CN Nachtmann 1 an x g ( x,q )dx= + tmc, 1 0 N 1 N =0,, 4,.. N (d N a N ) + tmc, N =, 4,.. ( N +1) (tmc: target mass corrections) 0 d is mean color-magnetic field along spin Nachtmann moments needed to get twist-3 free of tmc 1 ( ξ ξ M d (Q ) = dx ξ g 1 +3(1 ) g x Q 0 Deuteron Neutron Moments at Q 1.3 GeV x g ( x,q )dx= N Proton measured range 0.3< x<.8 plus elastic (quasi-elastic for deuteron) unmeasured low x <0.3 suppressed by x weight (OPE valid to N= < Q/M0 ~ 1.3/0.5 per DIS resonances duality) ) (Ji & Unrau, PR D5 (1995) 7) 1 Q dx x ( g 1+ 3 g ) 0 30

31 Operator Product Expansion for Spin SF's OPE connects SF's CornwallNorton moments to twist-, twist-3 matrix elements an, dn 1 x g 1 ( x,q )dx= N 0 1 an + tmc, N =0,, 4,.. N (d N a N ) + tmc, N =, 4,.. ( N +1) (tmc: target mass corrections) x g ( x,q )dx= N 0 d is mean color-magnetic field along spin (all data E ' >1.3 GeV, W > GeV. Only projected error shown.) Nachtmann moments needed to get twist-3 free of tmc 1 ( ξ ξ M d (Q ) = dx ξ g 1 +3(1 ) g x Q 0 SANE's measured C-N d ) 1 Q dx x ( g 1+ 3 g ) 0 31

32 Operator Product Expansion for Spin SF's OPE connects SF's CornwallNorton moments to twist-, twist-3 matrix elements an, dn 1 x g 1 ( x,q )dx= N 0 1 an + tmc, N =0,, 4,.. SANE N (d N a N ) x g ( x,q )dx= + tmc, N =, 4,.. ( N +1) 0 (tmc: target mass corrections) N d is mean color-magnetic field along spin Nachtmann moments needed to get twist-3 free of tmc 1 ( ξ ξ M d (Q ) = dx ξ g 1 +3(1 ) g x Q 0 ) SANE analysis near final version Publication in preparation 1 Q dx x ( g 1+ 3 g ) 0 3

33 Hall C 1 GeV Spin Physics Experiment E E E E Title Beam days Rating Measurement of the Charged Pion Form Factor to High Q Measurement of the Ratio R=sigmaL/sigmaT in Semi-Inclusive Deep-Inelastic Scattering Inclusive Scattering from Nuclei at $x > 1$ in the quasielastic and deeply inelastic regimes The Search for Color Transparency at 1 GeV Measurement of Neutron Spin Asymmetry A1n in the Valence Quark Region Using an 11 GeV Beam and a Polarized 3He Target in Hall C A Path to 'Color Polarizabilities' in the Neutron:A Precision E Measurement of the Neutron $g_$ and $d_$ at High $Q^$ in Hall C E E E E E E E E E E E E E Precision measurements of the F_ structure function at large x in the resonance region and beyond Deuteron Electro-Disintegration at Very High Missing Momentum Detailed studies of the nuclear dependence of F in light nuclei. Proton Recoil Polarization in the 4He(e,e'p)3H, H(e,e'p)n, and 1H(e,e'p) Reactions The Neutron Electric Form Factor at Q^ up to 7 (GeV/c)^ from the Reaction d(e,e'n)p via Recoil Polarimetry Scaling Study of the L-T Separated Pion Electroproduction Cross Section at 11 GeV Precise Measurement of pi+/pi- Ratios in Semi-inclusive Deep Inelastic Scattering PartI: Charge Symmetry violating Quark Distributions Studies of the L-T Separated Kaon Electroproduction Cross Section from 5-11 GeV Transverse Momentum Dependence of Semi-Inclusive Pion Production In Medium Nucleon Structure Functions, SRC, and the EMC effect Measurement of Semi-Inclusive Àæ Production as Validation of Factorization Exclusive Deeply Virtual Compton and Neutral Pion Cross-Section Measurements in Hall C E The Deuteron Tensor Structure Function b1 E E E E Precision Measurements and Studies of a Possible Nuclear Dependence of R Wide-angle Compton Scattering at 8 and 10 GeV Photon Energies Wide Angle Exclusive Photoproduction of pi-zero Mesons Initial State Helicity Correlation in Wide Angle Compton Scattering Total Spin Physics days A AAB+ A 9 A B+ B+ AB+ B+ 36 AA B+ AB+ AA A B AB B (Conditionally approved) 33

34 Extras 34

35 p p GE /GM from inclusive and coincidence data Ratio from: SANE inclusive HMS data at Q² =.06 GeV² p Ael = -0.0 ± 0.0 p p GE /GM = 0.60 ± 0.18 ± 0.06 ary ors only) n i m i Prel E stat. err (statistical + systematic error) BETAHMS ep coincidences at Q² = 5.66 GeV² p (SAN RSS p GE /GM = 0.67 ± 0.36 (statistical error only) (A. Liyanage) 35

36 SANE Collaboration (E ) P. Solvignon Argonne National Laboratory, Argonne, IL E. Brash, P. Carter, A. Puckett, M. Veilleux Christopher Newport University, Newport News, VA W. Boeglin, P. Markowitz, J. Reinhold Florida International University, Miami, FL I. Albayrak, O. Ates, C. Chen, E. Christy, C. Keppel, M. Kohl, Y. Li, A. Liyanage, P. Monaghan, X. Qiu, L. Tang, T. Walton, Z. Ye, L. Zhu Hampton University, Hampton, VA P. Bosted, J.-P. Chen, S. Covrig, W. Deconink, A. Deur, C. Ellis, R. Ent, D. Gaskell, J. Gomez, D. Higinbotham, T. Horn, M. Jones, D. Mack, G. Smith, S. Wood Thomas Jefferson National Accelerator Facility, Newport News, VA J. Dunne, D. Dutta, A. Narayan, L. Ndukum, Nuruzzaman Mississippi State University, Jackson. MI A. Ahmidouch, S. Danagoulian, B. Davis, J. German, M. Jones North Carolina A&T State University, Greensboro, NC M. Khandaker Norfolk State University, Norfolk, VA A. Daniel, P.M. King, J. Roche Ohio University, Athens, OH A.M. Davidenko, Y.M. Goncharenko, V.I. Kravtsov, Y.M. Melnik, V.V. Mochalov, L. Soloviev, A. Vasiliev Institute for High Energy Physics, Protvino, Moscow Region, Russia C. Butuceanu, G. Huber University of Regina, Regina, SK V. Kubarovsky Rensselaer Polytechnic Institute, Troy, NY L. El Fassi, R. Gilman Rutgers University, New Brunswick, NJ S. Choi, H-K. Kang, H. Kang, Y. Kim Seoul National University, Seoul, Korea M. Elaasar State University at New Orleans, LA W. Armstrong, D. Flay, Z.-E. Meziani, M. Posik, B. Sawatzky, H. Yao Temple University, Philadelphia, PA O. Hashimoto, D. Kawama, T. Maruta, S. Nue Nakamura, G. Toshiyuki Tohoku U., Tohoku, Japan K. Slifer University of New Hampshire H. Baghdasaryan, M. Bychkov, D. Crabb, D. Day, E. Frlez, O. Geagla, N. Kalantarians, K. Kovacs, N. Liyanage, V. Mamyan, J. Maxwell, J. Mulholland, D. Pocanic, S. Riordan, O. Rondon, M. Shabestari University of Virginia, Charlottesville, VA L. Pentchev College of William and Mary, Williamsburg, VA F. Wesselmann Xavier University, New Orleans, LA A. Asaturyan, A. Mkrtchyan, H. Mkrtchyan, V. Tadevosyan Yerevan Physics Institute, Yerevan, Armenia Ph.D. student, M.S. Student, Student 36

37 37

38 Why is g interesting? tests twist-3 effects = quark-gluon correlations higher twist corrections to g1 with 3rd moment d matrix element test of lattice QCD, QCD sum rules, quark models from moments polarizabilities of color fields (with twist-4 matrix element f) 3rd moment related to color Lorentz force on transverse polarized quark (M. Burkardt, AIP Conf.Proc (009) 6) magnetic B= (4d+ f)/3 and electric E= (4d - f)/3. sign of d related to sign of transverse deformation (anomalous q) contains chiral odd twist- = quark transverse spin (mass term) test quark masses (covariant parton models) 38

39 RSS Spin Structure Functions g1 F. Wesselmann et al., Phys.Rev.Lett. 98, (007) (including spin asymmetries A1, A) p,d In preparation 39

40 RSS Proton Spin Asymmetries Fit A1 and A independently Four Breit-Wigner resonance shapes plus DIS background Reduced = for 1 d.o.f. 40

41 g in DIS and Resonances inary m i l e Pr x g APS g Sprin 0.1 ) inary m i l e (Pr x E143 (SANE Q² range) E155x (SANE Q² range) (H. Baghdasaryan) Proton (NH3) Hall C SANE (E07-003) 0.3 < x < < Q < 6.5 SANE (E'>=1.3) SLAC x g(< Q² < 6 GeV²) Total errors SANE & E143, statistical only E155x 41

42 DIS Spin Asymmetry A JLab 0.3 ) inary m i l e (Pr 0. A p x SANE -3 GeV² 3-4 GeV² 4-5 GeV² SLAC DIS Ap not zero is signal of parton transverse momentum d (1) connection to transverse twist-3 TMD g 1T: g ( x)= dx g 1T ( x )+ g T ( x) 4

43 Nucleon Spin beyond G1 and G Need to go beyond a0 to understand nucleon spin Partons have transverse momentum, implies OAM Orbital angular momentum (OAM) L is needed. Muller, Ji, Radyushkin, Generalized Parton Distributions GPDs functions of Mandelstam t, light cone momentum ξ exclusive scattering, DV Compton, meson H x, =t =0 =q x = f 1 x H x, =t =0 = q x = g 1 x x,,t E x,,t, E (no partonic analogs) J q= dx x [ H q x,,t =0 E q x,, t=0 ] (Ji's sum rule) J q= q L q 43

44 Nucleon Spin beyond G1 and G Need to go beyond a0 to understand nucleon spin Partons have transverse momentum, implies OAM Orbital angular momentum (OAM) L is needed. Mulders et al., Transverse Momentum dependent Distributions TMDs functions of x and kt Semi-inclusive scattering (detect final e, one hadron) Transverse Momentum Distributions by Polarization Target \ quark U L T U f1(x, kt) h1_ _ L g1 h1l_ _ T f1t _ _ g1t _ _ h1 h1t _ _ Longitudinal SSF (leading twist) q g 1 (x )= g 1 (x)= d k t g 1 L ( x, k t ) Transverse SSF (twist-3) k t q k t ) g ( x)= g ( x)= d k t g ( x, 1T M d (1) g T (x)=g 1 (x )+ g 1T=g 1( x)+g ( x) dx (1 ) 1T q (1) 1T 44

45 Double Spin SIDIS ALT g1t (x, kt) is chiral-even TMD for quarks with longitudinal helicity in a transverse polarized target Weighted by kt/m and integrated over kt, generates a cos( - s) azimuthal ALT, measurable in SIDIS AL T x, y, z T / M cos s P = Hall A E06-010, PRL 108 (01) 0500 x C x, y e g 1 Dh z 1T C ' x, y e f 1 x D h z 45

46 Duality in g1 Bloom Gilman duality for spin SF's Local Duality only above (13) Global duality (for W > threshold, or from elastic) obtains above Q > 1.8 GeV seen in p, d, and 3He DIS SSF's from PDF's extrapolated with target mass corrections 1n E E01-01 Curves from TM corrected PDF's 46

47 Duality in g1 Bloom Gilman duality for spin SF's Local Duality only above (13) Global duality (for W > threshold, or from elastic) obtains above Q > 1.8 GeV seen in p, d, and 3He DIS SSF's from PDF's extrapolated with target mass corrections CLAS eg1b Bands: DIS g1 47

48 48