Hall C Inclusive Experiments: Update on measurements of longitudinal structure function of Nucleons and Nuclei. Eric Christy Hampton University

Transcription

1 Hall C Inclusive Experiments: Update on measurements of longitudinal structure function of Nucleons and Nuclei Eric Christy Hampton University HallC Winter Workshop,

2 Focus of this talk is an update on the nuclear target inclusive L/T separation experiments from 6 GeV.

3 Status of FL (R) data from Hall C Experiment target(s) W range Q2 range Status E p RR nucl-ex/ E p,d DIS+RR PRL98:14301 E p,d DIS+RR Analysis finalized/ Publication drafted E d RR+QE Finalizing d analysis E d RR+QE Cross section, FL finalized Non-singlet moments Finalized ~ Feb E I C,Al,Fe RR+QE Finalizing d analysis E II C,Al,Fe RR+QE Final Iteration of d in progress Final results Spring

4 E02-109, E06-009, E Unexpected, significant loss of manpower working on most recent experiments over last year + ½. However... progress has been ongoing recent dedicated effort will help finalize results for publication priority is to finalize / publish higher Q2 data from phase-ii Spring 2016: RD-RA non-singlet p-n moments 4

5 Reminder: longitudinal / transverse separations Reduced cross-section: QED (calculable)) nucleon structure) 1 dσ = σ T ( x,q 2 ) +εσ L ( x,q2 ) Γ d Ω de' Fit linearly with at fixed W2 and Q2 (or x, Q2). F2 σl = Slope σt = Intercept F1 F2 = (FL + 2xF1)/(1+ /Q ) 2 2 { FL Extraction of F2 depends on FL and! Important for Jlab kinematics need 1-2% uncertainties pt-pt in to provide 15-20% R ( FL/FL) also requires multiple beam energies and spectrometer settings for multiple. Very challenging experimentally! 5

6 Proton F2, F1, FL well measured at 6 GeV DIS fit 'F2ALLM' H.Abramowicz and A.Levy, hep ph/ Res fit - E.C. and P.E. Bosted, PRC 81, MRST2004+TM MRST2004 Alekhin Used to study Q H duality, structure function moments, and input for other physics studies Deuteron and nuclear target data of similar quality to study => duality and QCD moments of neutron and p n Modifications of F1, FL in nuclear medium May 20, 2014 E. Christy, NuInt14 6

7 Nachtmann Moments of proton FL P. Monaghan, A. Accardi, MEC, C.E. Keppel, W. Melnitchouk, L. Zhu, PRL 110, (2013). M (Ln ) ( Q 2 ) = dx x n 2 F (L0 ) ( x ) TM contributions have been removed from data via Nachtmann moments. Different PDF NLO results are similar at Q2 > 20, but are significantly different at Low Q2. Note that only ABKM includes H T terms in fit. Contribution partially absorbed in MRST gluon? Differences in higher moments likely due to underestimated Gluon strength At high x and/or H T contributions. 7

8 Proton Results utilized by many other experiments and physics studies R results utilized in extracting spin structure functions from asymmetries. quantitative duality studies. Global fits to resonance region F2, FL I. Input for radiative corrections II. Structure function moments III. BONUS extraction of F2n 8

9 FL, R on Deuterium and heavier targets JLab Hall C: E02-109, E04-001, E Precision extraction separated structure functions on D, Al, C, Fe/Cu Search for nuclear effects in FL, R. Neutron and p-n moment extractions (non-singlet calculated on Lattice). Allow study quark-hadron duality for neutron, nuclei separated structure function. 9

10 L/T kinematics (d, C, Al, Cu, Fe) Phase-II Phase-I 10

11 Main Contributers: Ibrahim Albayrak Vahe Mamyan Simona Malace 11

12 Recent Progress E06 009: Final deuteron cross sections and separated structure functions after model interation. Most of final systematic uncertainties determined Updated deuteron and NS moments determined Finalizing systematic uncertainties on NS moments E04 001: Updated carbon cross section model (other nuclei in progress) Code for evaluation of full systematics implemented 12

13 Updated phase-ii 12C and deuteron cross sections Correlated Systematic uncertainty Band includes: Radiative corrections 1%. Absolute dq = 0.6 mrad Charge symmetric bkgd 5%. Coulomb corrections Nuclear elastic normaliztion 2% For uncertainties on stucture functions shift cross sections reperform L/T separations 13

14 Carbon d comparisons to updated fit Blue: E phase II Black: other world data - Improvements at low Q2 - check on final data interation in progress - Fits to other nuclei in progress 14

15 FL (R) in Nuclei *Well known since the EMC experiment that the nuclear medium modifies nucleon structure functions. BCDMS EMC SLAC Antishadowing However, after 25 years the mechanism is still not fully understood. shadowing Is the effect different in F1 and F2? * The latter => Fermi motion EMC nuclear dependence of R and FL! Important to know if A dependence exists in FL for full understanding of EMC effect. 15

16 Highest precision data on RA comes from SLAC E139/E140 SLAC analysis showed no clear evidence for RA Rd... However Re-analysis of L/T separations (P. Solvignon, J. Arrington, D. Gaskell,ArXiv: ) including neglected Coulomb effects for electron entering and exiting nucleus Following Dasu et.al Analysis of SLAC (PRD ) σa σd = σ TA σ TD ' (1 +r ε ) r = RA Rd, ' = /(1+ R d) Much of systematics cancel! => RA < Rd?? 16

17 Also R, FL nuclear target data Dissertation of V. Mamyan (UVA) PRELIMINARY W2 W2 updated analysis results show same general trend and possible evidence for nuclear dependence in R => Different nuclear dependence in F2, F1, FL But final systematics pending May 20, 2014 E. Christy, NuInt14 17

18 Deuteron FL and Moments (E02 109, E06 009) 18

19 Status of FL deuteron data Preliminary Data from phase-ii finalized additional data at lowest Q2 from phase-i forthcoming. Final systematic uncertaintes Finalized, but not shown. May 20, 2014 E. Christy, NuInt14 19

20 Moment procedure: 1. Subtract QE contribution with data driven method scale QE model to data 2. Unfold nuclear / smearing effects, eg. F2(n+p) = F2d * (F2(n+p)/F2d)fit proton: Christy Bosted fit neutron/deuteron: recent fit by M.E.C, N. Kalantarians, J. Ethier, W. Melnitchouk 3. Integrate xn Fd2(L) (n=0,2,4,6) to get nth Md(n) deuteron moments 4. nth non singlet moment: MNS(n) = 2Mp(n) M(n+p)(n) 20

21 QE Subtraction Preliminary - QE shape taken from deuteron fit - QE model scaling factor determined by matching data at each Q 2 - Data in QE includes both Hall C and SLAC NE11 (averaged) 21

22 d F 1 integrand of CN moment Q2 = 2 QE subtracted Fermi corrected n=4 F1 integrand F1 integrand n=2 n=6 22

23 d F L integrand of CN moment QE subtracted and Fermi corrected FL integrand n=2 n=4 n=6 23

24 Methodology of D2 moment determinations From I. Albayrak

25 Moment uncorrelated uncertainties n=2 Uncertainty on moments determined by: n=4 1. vary data sampling gaussian with width given by pt-pt uncertainties. 2. determine moment for each Of 1000 different 'universes' n=6 3. distribution width gives Uncertainty on moment. 25

26 Final n+p, neutron, and non-singlet results expected over next month MNS(n) = 2Mp(n) Mp+n(n) Plan publication draft available by end of March 2016 Thanks! 26