Short Range NN Correlations (from Inclusive Cross Sections)

1. Short Range NN Correlations(from Inclusive Cross Sections) Nadia Fomin Los Alamos National Laboratory August 19th, 2011 Newport News, VA

2. Data mining E02-019 • Inclusive Quasielastic and Inelastic Data allows the study of a wide variety of physics topics • Scaling (x, y, ξ, ψ) • Superfast quarks [N. Fomin et al, PRL 105, 212502 (2010)] • Short Range Correlations – NN force [N. Fomin et al, arXiv:1107.3583,submitted to PRL] • Q2 –dependence of the F2 structure functions for a variety of nuclei • Momentum Distributions • Duality

3. Deuterium • Usually, we look at x>1 results in terms of scattering from the nucleon in a nucleus and they are described very well in terms of y-scaling (scattering from a nucleon of some momentum) • Quasielastic scattering is believed to be the dominant process F(y,q) x=1 Deuterium

4. F(y)  n(k) for 2H

5. Not so fast, heavy nuclei • Scaling is not perfect • Final State Interactions (known to exist from (e,e’,p), where the proton is absorbed in the nucleus) • Contribution from inelastic processes • Excitation of the nucleus – barrier to extracting momentum distributions Au

6. Other scaling variables? ycw– analogous to y, but accounts for the excitation of the residual nucleus (Ciofi degli Atti – PRC, 2009) Other scaling variables also exist, but this approach is model-dependent

7. High momentum nucleons - Short Range Correlations 3N SRC 2N SRC C. Ciofi degli Atti and S. Simula, Phys. Rev. C 53 (1996).

8. Short Range Correlations -- Not a new idea Independent Particle Shell Model : For nuclei, Sα should be equal to 2j+1 => number of protons in a given orbital However, it as found to be only ~2/3 of the expected value The bulk of the missing strength it is thought to come from short range correlations • NN interaction generates high momenta (k>kfermi) • momentum of fast nucleons is balanced by the correlated nucleon(s), not the rest of the nucleus

9. Short Range Correlations P_min (GeV/c) x • To experimentally probe SRCs, must be in the high-momentum region (x>1) • To measure the probability of finding a correlation, ratios of heavy to light nuclei are taken • In the high momentum region, FSIs are thought to be confined to the SRCs and therefore, cancel in the cross section ratios 1.4<x<2 => 2 nucleon correlation 2.4<x<3 => 3 nucleon correlation

10. Short Range Correlations – 2 Nucleons (CLAS and SLAC) 4He 56Fe Egiyan et al, Phys.Rev.C68, 2003 Plots by D. B. Day No observation of scaling for Q2<1.4 GeV2

11. 3He 3He E02-019 2N Ratios (A/D) α2N -Light-cone momentum fraction of the struck nucleon vs x Raw Cross Section Ratios vsα2N Onset of scaling occurs for fixed α2N, but not x

12. Onset of 2N SRC region is not A-independent 2H 197Au

13. E02-019: 2N correlations in A/D ratios 18° data <Q2>=2.7 GeV2 R(A, D) for α2N >1.275

14. CM Motion of the 2N pair • If we’re in the regime of quasielastic scattering from a nucleon in an n-p SRC at rest  σA/σDyields the number of nucleons in high momentum pairs relative to deuterium • Need to remove the smearing effect of the CM motion of the 2N SRC pairs • Enhances the high momentum tails in heavy nuclei • Correction was calculated via convolution of iron CM motion with deuterium n(k) Isoscalar corrections removed from SLAC and CLAS results (where applicable)

15. Short Range Correlations – 3N 1.4<x<2 => 2 nucleon correlation 2.4<x<3 => 3 nucleon correlation Egiyan et al, PRL 96, 2006

16. <Q2>(GeV2) CLAS: 1.6 E02-019: 2.7 E02-019 Ratios Preliminary • Excellent agreement for x≤2 • Very different approaches to 3N plateau, later onset of scaling for E02-019 • Very similar behavior for heavier targets • Need higher statistics data for a more definitive comparison

17. E02-019: 2N correlations in A/D ratios 18° data <Q2>=2.7 GeV2 R(A, D) for α2N >1.275

18. Examine the A dependence of SRCs – 2N • A-dependence, especially the 9Be looks very familiar • Possible connection to physics in a completely different kinematic regime

19. A EMC effect vs A • Beryllium strikes again

20. What does this mean ? • EMC effect appears to follow “local” density • Sounds like the short range structure that we would normally study at x>1 (result of nucleon interaction at short range) J.Seely, et al., PRL103, 202301 (2009)

21. SRC vs EMC • Suggests both effects could be sensitive to a similar quantity • Probing what happens when nucleons come close together Linear relationship between EMC effect and SRC L. Weinstein, E. Piasetzky, D.W. Higinbotham, J. Gomer, O. Hen, R. Schneor PRL 106:052301,2011

22. Overlapping nucleons enhancement of F2 structure function two-nucleon only two-nucleon only 5% 6 quark bag 5% 6 quark bag qD(x) Small effect, possible contribution to EMC effect? Noticeable effect at x>1

23. “Superfast” quarks Current data at highest Q2 (JLab E02-019) already sensitive to partonic behavior at x>1 N. Fomin et al, PRL 105, 212502 (2010)

24. The Future is now -- E08-014 (recently completed) δp = ±4.5% δp = ±3% E02-019 kin# 6.5 CLAS

25. Patricia Solvignon E08-014 -- Statistics Only half of the data are included (higher systematic errors for those not shown)

26. Soon….. • 2H • 3He • 4He • 6,7Li • 9Be • 10,11B • 12C • 40Ca • 48Ca • Cu • Au x>1 at 12 GeV Follow up experiments for EMC effect and x>1 approved with high scientific ratings EMC effect 12 GeV

27. Summary • E02-019 offer a very rich data set • 1 PRL, another one submitted • Results suggest a local density dependence of the EMC effect as well as SRCs • These hints and suggestions need to be further investigated with new experiments

28. Analysis repeated for other targets All data sets scaled to a common Q2 (at ξ=1.1) N. Fomin et al, PRL 105, 212502 (2010)