Spin Structure of the neutron (3He) in the resonance region Patricia Solvignon Temple University, Philadelphia For the JLAB Hall A and E Collaborations The Challenges of QCD and the Opportunities of the 12GeV Upgrade

JLab, June 22, 2005P. Solvignon, Users Group Meeting  Understand transition between partons and hadrons  Study of higher twists  Spin and flavor dependence of quark-hadron duality  Access high x bj region if duality is demonstrated and well understood

JLab, June 22, 2005P. Solvignon, Users Group Meeting E saw a hint of duality in g 1 ( 3 He) Figure from Seonho Choi

JLab, June 22, 2005P. Solvignon, Users Group Meeting  Ran in January-February 2003  Inclusive experiment: 3 He(e,e’)X  Measured polarized cross-sections differences and asymmetries  Form g 1, g 2, A 1 and A 2 for 3 He   Spokepeople: N. Liyanage, J-P. Chen, Seonho Choi Graduate Student: P. Solvignon Test duality on the neutron SSF

JLab, June 22, 2005P. Solvignon, Users Group Meeting  Polarized e - beam at 3.0, 4.0 and 5.0 GeV; P avg = (77  3)%  Both HRS in symmetric configuration at 25 o and 32 o :  Double statistics  Control systematics  PID= Cerenkov + EM calo.   /e reduced by 10 4   (e - ) > 99% JLab HALL A

JLab, June 22, 2005P. Solvignon, Users Group Meeting  Longitudinaltransverse  Longitudinal and transverse configurations  High luminosity: s -1 cm -2  2 independent polarimetries: NMR and EPR  Based on spin exchange between optically pumped Rb and 3 He  About 1% N 2 is added for quenching

JLab, June 22, 2005P. Solvignon, Users Group Meeting   -     -   A // raw =  A  raw =    +     +   A //(  ) =  //(  ) / 2  o born  o born =  o raw - 2(  N 2 /  3 He )  N + R.C.  //(  )raw = 2 A //(  )  o  //(  ) =  //(  )raw + R.C.  Generate asymmetries:  Measure unpolarized cross section:  Form polarized cross sections differences:  Can also get Born asymmetries:

JLab, June 22, 2005P. Solvignon, Users Group Meeting A //  A  A 1 =  -  D(1+  ) d(1+  ) (  // + tan(  /2)   )  A // A  A 2 =  +  D(1+  ) d(1+  ) MQ 2 E 1 g 1 =    4  e 2 E´ E +E´ MQ g 2 =   4  e 2 2E´(E +E´) ( -  // + E + E´ cos   E´sin    ) (D and d depend of R) Extract g 1 and g 2 directly from our data Need external input of R to form A 1 and A 2

JLab, June 22, 2005P. Solvignon, Users Group Meeting Measured parallel elastic asymmetry to check the correction for beam and target polarizations Data and simulation agree at a 5% level

JLab, June 22, 2005P. Solvignon, Users Group Meeting QFS model from J.W. Lightbody and J.S. O’Connell

JLab, June 22, 2005P. Solvignon, Users Group Meeting N 2 dilution applied 1 st pass radiative corrections and

JLab, June 22, 2005P. Solvignon, Users Group Meeting Agreement between left and right arms cross sections is at 2% level.

JLab, June 22, 2005P. Solvignon, Users Group Meeting  raw with both arms combined  exp =  raw -  N  N corrected for density ratio

JLab, June 22, 2005P. Solvignon, Users Group Meeting Smoothed  exp After R.C., we obtain  born

JLab, June 22, 2005P. Solvignon, Users Group Meeting DIS fit : no Q 2 -evolution included here

JLab, June 22, 2005P. Solvignon, Users Group Meeting Large negative contribution of  (1232)

JLab, June 22, 2005P. Solvignon, Users Group Meeting Still large negative contribution of  (1232). But, at lower x, resonances seem to oscillate around the DIS curve.

JLab, June 22, 2005P. Solvignon, Users Group Meeting The  (1232) disappears and the resonance data seems to approach the DIS behavior.

JLab, June 22, 2005P. Solvignon, Users Group Meeting No resonance structure can be seen anymore.

JLab, June 22, 2005P. Solvignon, Users Group Meeting DIS data on 3 He

JLab, June 22, 2005P. Solvignon, Users Group Meeting A 1 is large and negative in the  (1232) region.

JLab, June 22, 2005P. Solvignon, Users Group Meeting A 1 is still negative in the  (1232) region.

JLab, June 22, 2005P. Solvignon, Users Group Meeting The  (1232) vanishes while the non-resonant background is rising. A 1 becomes positive in the  (1232) region.

JLab, June 22, 2005P. Solvignon, Users Group Meeting The two highest Q 2 data sets agree with each other and show the same trend as DIS data.

JLab, June 22, 2005P. Solvignon, Users Group Meeting

JLab, June 22, 2005P. Solvignon, Users Group Meeting  2 nd pass radiative corrections  Extract the neutron SSF  Extract moments of SSF (e.g. GDH sum rule, BC sum rule)  E provides precision data of SSF on neutron ( 3 He) for 1.0 < Q 2 < 4.0 (GeV/c) 2  Direct extraction of g 1 and g 2 from our data  Overlap between E resonance data and DIS  test of Quark-hadron duality for neutron and nuclei SSF  E data combined with proton data  test of spin and flavor dependence of duality Still to do:

Extra slides

JLab, June 22, 2005P. Solvignon, Users Group Meeting