PoS(CD15)001 . 1 2 g http://pos.sissa.it/ = 0.02 GeV 2 , and proton and PT) calculations. 2 ), and show some χ 1 h at low Q , down to Q 1 2 g g and 1 g He target in Hall A. 3 † ∗ data is especially useful in testing the Chiral Perturbation theory ( measurement. In addition to this, we will discuss the transverse spin structure of the 2 2 d , provide an important tool to study the longitudinal spin structure. We will present an 2 g [email protected] neutron nucleon which can be accessedresults from using measurements chiral-odd done transversity on polarized distribution ( Speaker. This work is supported in part through funds provided by the U.S. Department of Energy under Contract Number overview of the experimental program topresent measure these some structure recent functions results at on Jefferson the Lab, and neutron polarizabilities, proton and Our understanding of nucleon spin structureJefferson is still Lab far have from made complete. significant Experiments contributionsspin conducted to structure at improve by our measuring knowledge of polarized the structure longitudinal functions, The low Q The spin-dependent sum rules and the spin polarizabilities, constructed from the moments of ∗ † Copyright owned by the author(s) under the terms of the Creative Commons c The 8th International Workshop on Chiral29 Dynamics, June CD2015 2015 *** - 03 JulyPisa, 2015 Italy Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). DE-FG02-94ER40818.The author would like to thankE06-010(d2n) the experiments spokespersons at and JLab collaborators for of providing saGDH, several EG4, useful SANE plots and and inputs. Kalyan Allada An Overview of Recent Nucleon SpinMeasurements Structure at Jefferson Lab Massachusetts Institute of Technology E-mail: PoS(CD15)001 ) ) ). 1 q h ,~ µν ν (2.3) (2.6) (2.1) (2.4) (2.5) (2.2) W : = ( ) 0 µ k ) ~ 0 , 0 p Kalyan Allada E − p = ( µ 0 = ( p is the Bjorken scaling µ , and transversity ( 2 q x ) with initial four-momentum , ) ) and a hadronic tensor ( l ν )) . The kinematics of the process 2 2 ν E θ θ µν Q M Q ( L 2 = , − ) 0 P cos P ν = . . P µν p q ( q − M 2 = 0.02 - 6 GeV . 2 X 1 P W Q 2 ( = 2 0 + µν y Q 2 ) + L 0 = 0 EE p M x 2 PT theory. The spin of the nucleon is also an E ( ( E since the target is at rest and the final (hadronic) l χ 4 2 ) from ' 2 q 0 α Q ~ 2 → 2 , = q g ) = M 2 P − ) 0 ( q = and N = ( σ dE PT) is used to describe the experimental data and make + 2 µ 1 d χ p Ω g Q P ) + ( d p ( q l = W . The four-momentum of exchanged virtual photon is X . In this proceedings an overview of these experiments along with some of the 2 and the scattering angle of the lepton is given by 0 E scatters off a nucleon and is detected with final four-momentum − ) is the negative of the squared four-momentum transferred and E k ~ 2 , = Q E = 2.0 GeV ν In the Born approximation, the differential cross section of the inclusive electron scattering In the process of inclusive lepton-nucleon scattering a lepton ( High-energy electron scattering is a powerful techniques for studying the internal structure of 2 = ( Q µ p with a nucleon can be expressed as a product of leptonic tensor ( where the nucleon’s four-momenta is undetected state is with can be described by following Lorentz invariant quantities: where variable which represents the fraction of nucleon momentum carried by the stuck quark. at preliminary and final results will be discussed. 2. Inclusive Electron Scattering predictions. The polarization of electron and nucleoncan provides additional be degrees used of freedom to which constructimportant observables quantity to that test has the spin not contribution is been experimentally completely well measured, understood.still the not contributions completely Although, from understood. transverse the quark Severallongitudinal longitudinal spin recent spin is quark experiments structure were functions conducted at JLab to measured nucleon. It has a longand history starting later from at pioneering CERN experimentsand and done is at DESY. detected SLAC In in in this a 60s spectrometer. process andQuantum While 70s, Electrodynamics the the (QED), electron-quark electron the interaction scatters is internal described fromChromodynamics dynamics by of (QCD). a well-known the QCD quark nucleon is in is welldistance the described understood scale), by nucleon and Quantum but verified it in isinteractions the not becomes perturbative so very region well complicated (short- understood to insuch describe. the as non-perturbative Hence, region Chiral at where Perturbation low quark-gluon energies, Theory effective ( field theory Nucleon Spin Structure Measurements at Jefferson Lab 1. Introduction PoS(CD15)001 (2.8) (2.9) (2.7) (2.10) (2.12) (2.11) , : one where Kalyan Allada  2 ) 2 d Q , x ( 2 ]. ) that arises from quark- 1  ζ ) Mxg ¯ s 2 . . . ∆ ) gives the quark momentum − dy dx y 2 ) and spin-dependent structure + dy )  ) 2 , 2 ) 2 s  Q ) F 2 ) , 2 ∆ Q Q , 2 x ( , Q , 1 y ( Q , x y Q 1 9 2 , F ( ( x , F x 1 1 ( y ( ( 2 g g 2 ) + ) g ¯ ζ ¯ 1 g 3 d θ x ) or Z ∆ 2 ) + ) + is the twist-2 (Wandzura-Wilczek) term and Q ) + 2 + cos 2 , 2 0 ) + Q d x Q 2 Q , ( E , ∆ 2 WW , y 1 x Q ( 3 ( x + F ]: ( , 1 ( 9 1 x 2 1 h E [ ( g ( q 1 2 WW 1  2 g M can be accessed experimentally by measuring the cross ) + g 0 m g has no simple interpretation in the native parton model.  ¯ u 2  E 2 − E 2 can be written as a sum of twist-2 and twist-3 terms: x ∆ g g 2 d 2 1 ) = dy 2 0 + 2 g Q ) = 1 Z , α u 2 ν Q x and 2 4 are the polarized quark(antiquark) distributions. , ∆ Z Q 1 x M ( ) , , can be constructed: ( g ¯ ) = s − 2 4 9 x 2 2 ( = ∆ d g provides a clean way to access the twist-3 effects. Also, using the  ( = Q 0 s 1 2 ( 2 2 ↑⇑ 2 2 WW ¯ g ∆ g ) is given by dE g d = σ is further split into two terms - one containing leading twist transversity ⇑ 2 Ω 1 ) probes the quark longitudinal spin distribution [ d 2 g and d 2 , g ) Q ¯ ], and in the other it is proportional to the instantaneous average sum of the − ] d , 4 0 x 3 ∆ ( ( ↓⇑ 1 ). In the naive parton model, ]. dE d g σ 2 5 ∆ ) suppressed by the quark mass, and a truely twist-3 part ( 2 Ω g , 1 d d ) , h ¯ 1 u dependent quantity, g = ∆ can be related to a specific matrix element containing local operators of quarks and is the higher twist (twist-3) term and g 2 ( || 2 u 2 Q σ d g ∆ ∆ The spin structure functions The second spin structure function can be determined from the twist-2 part of where ¯ distribution ( The higher twist term ¯ gluon interactions [ Hence the measurement of section differences between twoverse) different with target respect to polarization the directionslongitudinally electron polarized (longitudinal beam ( polarization. and trans- The cross section difference when target is transverse electric and magnetic forcevirtual the photon struck [ quark experiences at the instance it is hit by the OPE, a it is expressed as aover quark linear flavors combination [ of electric and magnetic “color polarizabilites”, summed Nucleon Spin Structure Measurements at Jefferson Lab The leptonic tensor can bea calculated precisely combination in of QED, symmetric andhadronic the and hadronic structure antisymmetric tensor into parts. can spin-independent be structure Thisfunctions written functions as effectively ( ( parametrizes the internal where It is related toexpansion the (OPE) quark-gluon analysis correlation at high through Q higher twist effects. In the operator product where gluon fields, and is calculable in lattice QCD. There are two interpretations of distribution and PoS(CD15)001 . . 2 1 g g are 2 (3.3) (3.4) (3.2) (3.1) / (2.13) 3 and σ 1 is zero at g . 2 ) and g 2 Kalyan Allada 2 1 . / Q 1 θ ( σ O sin  + . The top plot shows is given by ) 1  1 2 g ), a static property in the Q ... , 3 κ x ) ( s 2 , π moment to the nucleon axial α g 2 2 1 κ g M M ν 2 α 215 2 . to the polarized quark distributions 0) where it is related to from the measured cross sections. π 1 . . ) + 20 th moment of 2 2 > g 2 0 n g ) is given by dx − 2 − Q ) = , 2 2 Q ⇒ x ) = ( s Q and dx i ]( 1 , π α ) ) 1 9 g x 2 g (  ν 0 1 ( Q ] states that the first momentum of 2 g , E 56 E / . 8 1 x 4 = 0 to a large value. 3 2 3 ( region. Recent measurements from JLab on proton − 2 2 σ 2 n Q 2 − g x Q α ν − Q 1 1 s 4 0 0 ) π α M Z Z ν ( − = 2 ≡ = ) and it was found to be violated, resulting in “spin-crisis” / -decay. It can be expressed as 1 0 2 n 1 ∞ β  Γ Γ σ ↑⇒ A dE h ] links the isovector part of the 6 → σ g 7 ν Ω 2 ν 2 d d d ] relates the first moment of Q 6 ∞ 0 ) = − ν n 1 0 Z g 150 MeV is the threshold energy for pion production. ↓⇒ region. − dE ≈ σ p 2 1 ) Ω 2 g Q π d d ( M 1 m 2 0 = Z + ⊥ 1 ≡ ( σ ) π ∆ 2 represent the electron polarization along (opposite) to the beam direction. The cross m Q ) ) that governs the neutron ( ↓ = A n ( g 0 − ) in the Bjorken limit ( : p ↑ 1 ν d 2 Γ The Gerasimov-Drell-Hearn (GDH) sum rule links the energy-weighted photoabsorption cross The Burkhardt-Cottingham (BC) sum rule [ The experimentally measured spin structure functions are expressed as moments in order to The Ellis-Jaffe sum rule [ ∆ Q , u ∆ The current results of BC sum rule for proton and neutron are shown in Fig. the photoabsorption cross-sections where 1/2 andthe 3/2 center are of the mass sum system. of photontion The and cross GDH target sections integral helicities has in to been virtualThis generalized allows photon by constraining cross replacing GDH sections the integral photoabsorp- from [ any the proton data and theThere bottom is plot not shows much the data existing on neutron proton data in the for low the second moment of ground state: where section, a dynamical quantity, to particle’s anomalous magnetic moment( target covers this low ( in 1980s. The Bjorken sum rule [ Nucleon Spin Structure Measurements at Jefferson Lab where section difference when target is transversely polarized ( charge ( compare them to theoretical calculations. For example, the Using the two equations above one can extract both 3. Moments of Spin Structure Functions and Sum Rules Using the moments of structurealso be functions used several to spin test summoments the rules of theoretical have predictions. spin been structure Spin proposed sumtheoretically functions which calculable. rules to can are Therefore, static sum important rules properties quantities provide that of an relate nucleon important way or to the study QCD. quantities that can be PoS(CD15)001 x is 3 (3.5) (3.6) Kalyan Allada , . dx targets have been used in i dx ) 3  2 ) 2 Q to measure the spin structure , Q x , 3 ( were performed by three experi- x 2 ( 2 g 2 2 ] Q g x 2 He and NH 2 10 Q 2 3 ) + M Q 2 4 Q He or NH at low He nucleus. This target provides very high , 3 − 3 2 x ) He can be used as an effective neutron target ( describe the response of the nucleon to photon g is used as a proton target and polarized ND 2 3 1 3 g Q LT 2 , 5 δ x x and (  1 1 0 targets. These targets provide polarized luminosities g x g and 0 3 h Z 0 0 x γ 2 0 Z M 6 2 α Q and ND M 6 . Polarized NH 16 1 3 α Q − 16 ) = cm 2 1 Q − ) = ( He is dominated by the S-state, where two proton spins are anti-aligned s 2 3 LT Q 36 ( δ 0 γ using the CLAS detector. 1 − cm 1 − s Current results of BC sum rule. The top plot shows proton data and the bottom plot shows neutron 34 The generalized spin polarizabilities Experiments at JLab use the polarized electron beam with energies up to 6 GeV (now upgraded The most recent JLab measurements of and elastic region contributions included. Reproduced from Ref. [ functions. The measurements discussed belowHall were performed A in consists the of experimental two halls highelectron A cross resolution and sections spectrometers B. with (HRSs) high which precision.Hall are Both used A polarized to for measure spin inclusive structuresince measurements. the Polarized ground state of luminosities of up to 10 Figure 1: results. The open circles represent measured data, while black diamonds show the total integral with low- and the remaining neutron carries most of the spin of 4.1 Longitudinal Spin Structure Measurements at Low up to 10 to 12 GeV) and polarized targets such as polarized Nucleon Spin Structure Measurements at Jefferson Lab absorption and are connected to the higher moments of polarized structure functions. 4. Spin Structure Measurements at JLab used as a deuteron target.method, These operating targets under are very high polarized magnetic using fieldCLAS Dynamic (5 detector Nuclear T). and Hall Polarization B polarized (DNP) measurements NH were made using the ments: E97-110 and E08-027 experiments in Hall A and the EG4 experiment in Hall B. The EG4 PoS(CD15)001 ⊥ ∆ . The 2 and the ]. and their LT 2 15 δ g , Kalyan Allada 14 for proton. The , and He target in lon- 2 3 1 ). The goal of the g 13 2 g structure function at low 2 for proton. The experiment g . The results from this ex- 0.7 GeV 3 2 < Γ 2 structure function for both pro- Q 1 g coverage in the E08-027 experiment. PT theory and cross checking with < 2 χ Q on both proton and deuteron targets. (0.02 1 2 g Q ] is to extract proton range for this experiment was from 0.04 - 0.24 , are shown in Fig. targets, respectively. The experiment performed n 1 , along with 6 12 2 3 Γ 1 Q Γ -resonance and vector meson contributions. The heavy ∆ and and ND LT δ from EG4 experiment in Hall B to obtain 3 0. The final analysis of the data from this experiment is under ]. The data agrees well with the models. The shaded band || . The experiment measured spin-dependent cross section → 2 ∆ 19 2 , Q 18 ] are shown in red dotted curve which agrees with the data only for the 0.2 GeV 20 PT as ] used CLAS detector to measure the < χ 11 2 Q ]. < 17 ]. 17 The projected uncertainties of points [ , PT calculations [ 2 χ 16 [ Q 2 The preliminary results for first moment, The E97-110 experiment utilized polarized electron beam and a polarized The goal of E08-027 experiment in Hall A [ region of 0.02 2 Figure 2: baryon shows calculations with an estimate of the lower ton and deuteron using polarizeddoubly NH polarized inclusive electron scattering at low Q and will combine with the dataprojected on statistical precision and the kinematical reach for this experiment are shown in Fig. gitudinal or in-plane transverse directionferences. to measure Using doubly the polarized measured inclusive crossmoments cross sections for section the neutron dif- polarized were structure extracted.gral functions using The the goal measured of cross this sections. experiment was The to extract the GDH inte- periment are shown in redand triangles, HERMES. The along error with bars previous includeshown measurements both in from statistical the and JLab, plot systematic. SLAC are E143 The two from model calculations [ GeV Nucleon Spin Structure Measurements at Jefferson Lab experiment in Hall B [ experiment is to test the progress and very preliminary results are available for blue data points of thesame left for the side right plot side plot shows shows the the projections projections for for second moment LT spins polarizibility is currently in the advanced stages ofdata analysis will and be expected to very have crucial preliminarythe results for soon. most testing recent These our calculations understanding of of spin the polarizibilities from various theory groups [ PoS(CD15)001 ) 2 and 0 γ were ex- 0.15 GeV LT Kalyan Allada δ < ( 2 Q and PT calculations are 0 χ γ from E07-110 experiment are . Two 2 0 ] shown in red dotted line has γ Q 22 from E07-110 experiment are shown in 2 Q . The red data points show the results 4 PT calculation [ 7 ] shown in light blue band agrees reasonably well χ 21 shown in the figure do not agree with the data. There are for neutron as a function of LT LT δ . The HB δ 2 and for neutron as a function of 0 1 γ Γ data, which maybe be due to the large resonance contributions to this PT calculations [ 0 χ γ below 0.12 GeV 2 PT calculations for χ Q ]. The preliminary results are shown in Fig. Preliminary results of Preliminary results of 16 data for 0 γ Using the data from this experiment the neutron spin polarizabilities the calculations from MAID model agree reasonably well, although, at low LT tracted [ shown in red color. The error bars represent statistical and the red band shows the systematics. large discrepancy with the observable. The from this experiment, along withred previous band JLab near measurements zero (shown showsδ in the blue systematics data uncertainties points). for the The this experiment. For both with Figure 4: the MAID model calculations are slightly higher than the data for Figure 3: Nucleon Spin Structure Measurements at Jefferson Lab red color. shown on the plot. The RB PoS(CD15)001 1 g and from 2 shows region 2 g g x LT ) target to δ . from SANE 3 2 and x d Kalyan Allada 1 g ] and using axial 14 0.8. The experiment ≤ for proton as a function x PT [ ] and E06-014 (d2n) ex- 1 χ for the neutron g ≤ 2 23 x . The data from past experiments 2 is shown in color, along with the et al., Q 2 ]. The data was used to extract and 0.3 Q 2 25 ], covariant B 13 (right) for proton as a function of 2 6.5 GeV at JLab were performed by two experiments: g 2 ≤ g 2 8 Q . The experiment used two spectrometers, a high and , where 180 and 80 indicates the target polarization ≤ 2 1 (left) and 80 g 1 PT approach [ g 0.9) using 4.7 GeV and 5.9 GeV polarized beam and a χ for proton. The systematic bands are shown below the data . The data from different ≤ 2 and A 5 g x PT calculations by V. Lensky 2 χ x 180 ≤ using B -weighted 2 and 4.32 GeV x LT (0.2 2 δ x measurements of ]. The B 2 ]. The goal of the SANE experiment was to measure the proton 15 Q 24 in the kinematic range 2.5 1 A of 3.21 GeV Measurements of Longitudinal Spin Structure Function He target which in turn was used for the extraction of neutron twist-3 matrix element 3 > 2 He target in longitudinal and transverse direction [ 2 Q 3 Preliminary results of region. These data will be used to extract the proton twist-3 matrix element Q x from < 2 The E06-014 experiment measured the double spin asymmetries (DSA) in deep inelastic and Most recent high and the right side plot shows g at x n 2 used polarized electron beam ofmeasure the 4.7 spin GeV asymmetries, and A 5.9 GeV on a polarized ammonia (NH SANE experiment are shown in Fig. and d resolution spectrometer (HRS) for the crossspectrometer section for measurements, asymmetry and measurements a in large Hall acceptance A. BigBite Figure 5: anti-parallel and near-perpendicular to the incomingacceptance beam electron direction. detector which The consists experimenthodoscope of used and a a an forward large tracker, electromagnetic gas calorimeter. Cherenkov The detector, preliminary a lucite results of proton anomaly contribution [ periment in Hall Aspin [ asymmetry experiment. The colored data areare also from shown SANE in experiment black at color. different resonance region at large Nucleon Spin Structure Measurements at Jefferson Lab three recent calculations of previous world data which is shown in black. The left side plot shows to high polarized points with corresponding color. This experiment extended the kinematic range from low reasonable agreement with MAID model estimations and the experimental data. 4.2 High the Spin Asymmetries of the Nucleon Experiment(SANE) in Hall C [ of PoS(CD15)001 dramatically . The data is Kalyan Allada 2 6 g shows the same 7 is a charged hadron h -weighted polarized spin struc- )X, where 2 h x 0 e He is shown in Fig. , 3 e of He( 1 3 g . The red and blue data points are from E06-014 ), that describes the nucleon structure in lead- x 1 g He. The neutron information was extracted from 9 3 ]. for 2 25 . These data improved the precision of d 7 ) is the third important parton distribution, along with unpolarized 1 h He plotted as a function of 3 He target in the SIDIS reaction 3 for 1 g He is shown in Fig. 3 of ) and longitudinal spin distribution ( 2 1 ]. The measurement was done by scattering off longitudinally polarized electrons on g f -weighted 26 -weighted polarized spin structure function ). An electron beam with energy of 5.9 GeV was used. The scattered electrons were 2 2 x ± x K or The E06-010 experiment at JLab measured the Collins and Sivers moments on effective neu- Transversity distribution ( The ± He using effective polarization approach [ π tron target which will bespectively used [ in extracting the transversity and Sivers distribution functions, re- ing order. Transversity describes the distributionpolarized of nucleon. transversely This polarized can quarks be in studiedleading a in hadron transversely is semi-inclusive deep detected inelastic in scattering coincidencetion (SIDIS) with that where the can a scattered be electron. accessed Another innumber interesting SIDIS density distribu- process of is unpolarized the partons Sivers insidefunction function. a components The transversely with Sivers polarized nonzero function orbital proton, angular provides and momentumthe the it and correlation requires thus between wave provides the information quark about orbital angular momentum (OAM) and nucleon spin. 4.3 Transverse Spin Structure Measurements distribution ( a transversely polarized over the previous measurements from JLabresults and as SLAC. the The top bottom but plotat with of each y-axis beam Fig. zoomed energy by3 were a used to factor extract 10. The measured DSAs and cross sections Figure 6: experiment. The blue and red bands on the plot represents systematics and the error bar represent statistical. Nucleon Spin Structure Measurements at Jefferson Lab consistent with the previous experiments at JLabture and function SLAC. The ( detected in the large acceptance BigBitethe Spectrometer standard and Hall the produced A hadronsspin spectrometer. were asymmetry detected was The in constructed target from spinfocused the on was data the flipped collected valence quark in every region. each 20 spin minutes state. and The the kinematics single were PoS(CD15)001 Kalyan Allada for the electroproduction x . The world data is shown in black and the data x 10 He target. The bands below the data points represent the experimental and 3 He plotted as a function of 3 for 2 g (right) from − π -weighted 2 The extracted neutron Collins (top) and Sivers (bottom) moments vs x (left) and + π of model uncertainties, which are labeled as Exp and Fit, respectively. Figure 8: Figure 7: Nucleon Spin Structure Measurements at Jefferson Lab from E06-014 is shown inthe color. error The bar blue represent and statistical. red The bands bottom on plot is the a bottom zoomed plot by (b) a represents factor systematics 10 and from the top plot. PoS(CD15)001 = 0.34 is x Kalyan Allada ]. Both the data He asymmetries , provide crucial 3 31 were measured on LT , is extracted which , . The error bars on δ 2 2 g − 30 d π from the measurements and 2 and 0 g γ 1 g , 409-416 (1992). and 1 55 g , 136 (1989). asymmetries favor negative values, , 1 (2009). data of + 49 63 2 π , 453 (1970). Q 56 ]. 32 11 , 195 (1977). 0. The high 72 ] and model calculations, which include a light-cone ] and quark-diquark calculations [ → 27 2 29 , 1444 (1974). , 9 Q , 1893 (2010). 28 19 measurements of spin polarizabilites, , 114502 (2013). , 1467 (1966). 2 88 and the right-hand side shows the results for Q 148 + π level. For the Sivers moments, the σ in the top and bottom panels, respectively. The left-hand side of the plot PT calculations as 8 χ results are consistent with zero within the uncertainties. These data, along with − π arXiv:hep-ph/9510362. We discussed recent results of nucleon structure functions The results for the extracted neutron Collins and Sivers moments from the [1] S. E. Kuhn, J. P. Chen and E. Leader, Prog. Part. Nucl. Phys. [5] M. Burkardt, Phys. Rev. D [2] S. Wandzura and F. Wilczek, Phys. Lett.[3] B J.L. Cortes, B. Pire, J.P. Ralston, Z.[4] Phys. CX.-D. - Ji, Particles Proceedings and of Fields the 7th International Conference on the Structure of Baryons, Santa Fe, 1995, [6] J. Ellis and R. L. Jaffe,[7] Phys. Rev. D J. D. Bjorken, Phys. Rev. [8] H. Burkhardt and W. N. Cottingham, Ann.[9] Phys. (N.Y.) M. Anselmino, B. L. Ioffe and E. Leader, Sov. J. Nucl. Phys. both proton and neutron targets. Using thesewill data provide the twist-3 test matrix of element, latticeJLab QCD by predictions. measuring Collins Finally, the andThese transverse data Sivers are spin moments used structure on in was the an studied global effective analysis at neutron for target the extraction for of theReferences transversity distribution first function. time. [10] J.-P. Chen, Int. J. Mod. Phys. E, [11] M. Battaglieri, A. Deur, R. De[12] Vita and M.A. Ripani, Camsonne, JLab J. experiment P. Chen E03-006. and K. Slifer, JLab experiment E08-027. the points indicate the statisticalexperimental precision (Exp) of and the fitting data, (Fit) whereasare systematic the uncertainties. less bands than The on total 25% the experimental bottom ofignoring uncertainties show the the the statistical pretzelosity uncertainty and incompared higher each with twist bin. terms a in phenomenological Theconstituent the fit fitting quark extraction [ model uncertainties (LCCQM) of result [ the from and moments. the calculations The indicate data that are the Collins asymmetries are small, though the data at 5. Summary shows the results for the Nucleon Spin Structure Measurements at Jefferson Lab are shown in Fig. more negative at the 2 whereas the performed at JLab. 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Sulkosky, An Overview of Longitudinal Spin Structure Measurements from JLab, Proceedings[18] of J. Soffer and O. V. Teryaev, Phys. Rev. D [15] N. Kochelev and Y. Oh, Phys. Rev.[16] D V. Sulkosky, The Spin Structure of [23] S. Choi, M. Jones, Z-E. Meziani[24] and O.B. A. Sawatzky, Rondon, S. JLab Choi, experiment X. E07-003 Jiang (SANE). [25] and Z.-E.Meziani, JLabM. experiment Posik E06-014 et (d2n). al., Phys. Rev. Lett. [26] X. Qian. et al. Phys. Rev.[27] Lett. M. Anselmino et al. Phys. Rev.[28] D S. Boffi et al. Phys. Rev.[29] D B. Pasquini, S. Cazzaniga, and S. Boffi. Phys. Rev. D Nucleon Spin Structure Measurements at Jefferson Lab [13] V. Lensky, J. M. Alarcon and V.[14] Pascalutsa, Phys. Rev.V. Bernard, C E. Epelbaum, H. Krebs, Ulf-G. Meißner, Phys. Rev. D [30] J. She and B. Q. Ma. Phys. Rev. D [31] B. Q. Ma, I. Schmidt, and[32] J. J.Z-B Yang. Phys. Kang, Rev. A. D Prokudin, P. Sun, F. Yuan, arXiv:1505.05589.