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Eli Piasetzky

Short Range Correlations and the EMC Effect. Work done in collaboration with: L. B. Weinstein (ODU) D. Higinbotham, J. Gomez (JLab) O. Hen, R. Shneor (TAU). Eli Piasetzky. Tel Aviv University, ISRAEL.

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Eli Piasetzky

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  1. Short Range Correlations and the EMC Effect Work done in collaboration with: L. B. Weinstein (ODU) D. Higinbotham, J. Gomez (JLab) O. Hen, R. Shneor (TAU) Eli Piasetzky Tel Aviv University, ISRAEL

  2. Deep Inelastic Scattering (DIS) E E` Incident lepton scattered lepton (,q) W2 nucleon Final state Hadrons xB gives the fraction of nucleon momentum carried by the struck parton Electrons, muons, neutrinos E, E’ 5-500 GeV Q2 5-50 GeV2 w2 >4 GeV2 Information about nucleon vertex is contained in F1 (x,Q2) and F2(x,Q2), the unpolarized structure functions 0 ≤ XB ≤ 1

  3. DISis a hard process that has the resolving power required to probe the partonic structure of hadrons Nucleons Scale: several tens of GeV Nucleon in nuclei are bound by ~MeV Naive expectation : DIS off a bound nucleon = DIS off a free nucleon (Except some small Fermi momentum correction)

  4. The European Muon Collaboration (EMC) effect DIS cross section per nucleon in nuclei ≠ DIS off a free nucleon

  5. SLAC E139 Data from CERN SLAC JLab 1983- 2009 Theoretical interpretations: hundreds of papers G. Miller: EMC = Every Model is Cool

  6. EMC is alocal density effect,not a bulk property of nuclear medium JLab / Hall C J. Seely et al. PRL 103, 202301 (2009)

  7. Inclusive electron scattering A(e,e’) 2N-SRC 3N-SRC E E` Incident electron scattered electron (,q) 2N-SRC A hard process that has the resolving power required to probe the partonic structure of nuclei E, E’ 3-5 GeV Q2 2 GeV2 nucleus 0 ≤ XB ≤A Nucleons xB counts the number of hadrons involved

  8. Inclusive A(e,e’) measurements Adapted from Ciofi degli Atti • At high nucleon momentum, • distributions aresimilarin shape for • light and heavy nuclei:SCALING. • Can be explained by 2N-SRC dominance. • Within the 2N-SRC dominance picture, one can get the probability of 2N-SRC in any nucleus, from the scaling factor. For fixed high Q2 and xB>1, xB determines a minimum pi Deuterium Q2=2 GeV2 Prediction by Frankfurt, Sargsian, and Strikman:

  9. JLab. CLAS A(e,e') Result K. Sh. Egiyan et al. PRC 68, 014313 (2003) Observed “scaling” means that electrons probe high-momentum nucleons in 2(3) -nucleon phase. The scaling factors determine the per-nucleon probability of the 2(3) N-SRC phase in nuclei with A>3, relative to 3He. K. Sh. Egiyan et al. PRL. 96, 082501 (2006) For 12C 2N-SRC (np, pp, nn) = 20 ± 4.5%. The probabilities for 3N SRC are smaller by one order of magnitude relative to the 2N SRC. More r(A,d) data: SLAC D. Day et al. PRL 59,427(1987) JLab. Hall C E02-019

  10. New Preliminary Results from JLab Hall C (E02-019) Q2=2.5GeV2 a2N(A/d)

  11. : Comparing the magnitude of the EMC effect and the SRC scaling factors SRC scaling factor EMC slope SLAC data: Frankfurt, Strikman, Day, Sargsyan, Phys. Rev. C48 (1993) 2451. Q2=2.3 GeV/c2 Gomez et al., Phys. Rev. D49, 4348 (1983). Q2=2, 5, 10, 15 GeV/c2 (averaged)

  12. EMC Slopes 0.35 ≤ XB ≤ 0.7 SRC Scaling factors XB ≥ 1.4

  13. Deuteron is not a free np pair EMC The slopes for 0.35 ≤ XB ≤ 0.7 0.079±0.06 bound to free n p pairs (as opposed to bound to deuteron) SRC A SRC=0 free nucleons

  14. The free neutron structure function For 0.35 ≤ XB ≤ 0.7 Fermi smearing using relativistic deuteron momentum density SLAC Data, J. Arrington et al. JPG 36(2009)205005. World parameterization of Fd, Fp With medium correction Extracted from this work Corrected for the EMC effect as calculated in a PLC model

  15. Where is the EMC effect ? 80% nucleons (20% kinetic energy) SRC np Mean field Largest attractive force 20% nucleons (80% kinetic energy) pp nn Nuclei are optimized to yield the strongest EMC effect possible OR High local nuclear matter density, large momentum, large off shell. large virtuality ( )

  16. How large is EMC effect in dense nuclear systems? What are the consequences of a large EMC in these systems? n stars Central HI collisions

  17. EMC Summary The EMC is a local density effect not a bulk property of the nuclear medium. SRC The magnitude of the EMC effect and SRC scaling factor are linearly related. We speculate that observed correlation arises because both EMC and SRC are dominated by high momentum (large virtuality) nucleons in nuclei. The observed phenomenological relationship is used to extract: ( For 0.35 < XB < 0.7 ) ratio of deuteron to free n p pair cross sections. DIS cross section for a free neutron. 0.079±0.06 SRC=0 F2n(x,Q2), thefree neutron structure function.

  18. I thanks the organizers for the invitation arXiv:1009.5666 [hep-ph]

  19. Hard exclusive measurements EVA / BNL E01-015 / Jlab p p SRC: pair with “large” relative momentum between the nucleons and small CM momentum. p n “Redefine” the problem in momentum space A triple – coincidence measurement K 1 K 1 > KF , K 2 > KF KF ~250 MeV/c K 2 (E07-006) • K 1 -K 2

  20. Fe(e,e’pp) Pb(e,e’pp) Ein =5.014 GeV Q2=2GeV/c2 X>1.2 JLab / CLAS Data Mining, EG2 data set, Or Chen et al.

  21. R. Subedi et al., Science 320, 1476 (2008). BNL / EVA 12C(e,e’pn) / 12C(e,e’p) [12C(e,e’pn) / 12C(e,e’pp)] / 2 [12C(e,e’pp) / 12C(e,e’p)] / 2

  22. At 300-500 MeV/c, there is excess strength in np momentum distribution due to strong correlations induced by the tensor NN potential. pp/np 3He 3He np np pp pn pp V18 pp Bonn 3He Schiavilla, Wiringa, Pieper, Carson, PRL 98,132501 (2007). Ciofi and Alvioli PRL 100, 162503 (2008). Sargsian, Abrahamyan, Strikman, Frankfurt PR C71 044615 (2005).

  23. (e,e’) 60-70% 10-20% 20±5% Deduced short range 12C structure is: 60-70 % - independent particle in a shell model potential. 80 ± 4.5 % - single particle moving in an average potential. 10-20 % - shell model long range correlations (e,e’p) 18 ± 4.5 % - SRC np pairs . (p,2pn) 20 ± 4.5 % - 2N SRC . 0.95±0.2% - SRC pp pairs. 2N-SRC n-p pairs p-p pairs 74-92 % 4.75±1% 0.95±0.2 % - SRC nn pairs. (e,e’pN) 4.75±1% n-n pairs Small ~1% - SRC of “more than 2 nucleons”. ? ~1% -non nucleonic degrees of freedom (e,e’)

  24. 4 4 6 3 2 6 1 3 1 2 2 1 What did we learn recently about SRC ? Standard model for short distance structure of nuclei CLAS / HALL B The probability for a nucleon to have momentum ≥ 300 MeV / c in medium nuclei is ~25% More than ~90% of all nucleons with momentum ≥ 300 MeV / c belong to 2N-SRC. . PRL. 96, 082501 (2006) ~80% of kinetic energy of nucleon in nuclei is carried by nucleons in 2N-SRC. Probability for a nucleon with momentum 300-600 MeV / c to belong to np-SRC is ~18 times larger than to belong to pp-SRC. PRL 98,132501 (2007). Dominant NN force in the 2N-SRC is tensor force. EVA / BNL and Jlab / HALL A Three nucleon SRC are present in nuclei. PRL 162504(2006); Science 320, 1476 (2008).

  25. p Summary of Results γ n A(e,e‘p) 12C(p,2p n) Tang et al. PRL 042301 (2003) Long range (shell model) correlations Piasetzky, Sargsian, Frankfurt, Strikman, Watson PRL 162504(2006). 12 C 2N-SRC 60-70% 10-20% n-p pairs Single nucleons 20±5% 74-92 % 4.75±1% p-p pairs 2N-SRC 4.75±1% n-n pairs A(e,e‘pN) A(e,e‘) R. Subedi et al., Science 320, 1476 (2008). Egiyan et al. PRC 68, 014313. Egiyan et al. PRL. 96, 082501 (2006)

  26. EMC data J. Gomez et al. Phys. Rev.D49, 4348 (1983) N. Fomin Ph. D thesis, UVA (2007) arXiv:0812.2144 EMC Slope 0.3 ≤ XB ≤ 0.7 SRC data K. Egiyan et al. Phys. Rev Lett. 96,082501 (2006). J. Seely et al. Phys. Rev. Lett. 103,202301 (2009) Scaling factors XB ≥ 1.2 SRC

  27. EMC Slope 0.3 ≤ XB ≤ 0.7 SRC

  28. Q2 dependence of the EMC effect J. Seely et al. PRL 103, 202301 (2009) EMC data: Gomez et al. : average over 2, 5, 10, 15 GeV/c2 Seely et al. : 5.3 GeV/c2 Q2 for a2: Nadia: 2.71 Egiyan: 1.4 - 2.6 Day: 1 - 3

  29. J. Seely et al. PRL 103, 202301 (2009) Hall C preliminary data, N. Fomin Ph. D thesis, UVA (2007) arXiv:0812.2144 The average density is calculated from the ab initio Greens Function Monte Carlo calculation of the spatial distributions of Pieper and Wiringa, Annu. Rev. Nucl. Part. Sci. 51, 53 (2001).

  30. We know more about SRC from Hard exclusive measurements 2 4 2 3 1 1 2 3 6 4 6 1 CLAS / HALL B probability for a nucleon to have momentum ≥ 300 MeV / c in medium nuclei is ~25% more than ~90% of all nucleons with momentum ≥ 300 MeV / c belong to 2N-SRC. . PRL. 96, 082501 (2006) ~80% of the kinetic energy of nucleon in nuclei is carried by nucleons in 2N-SRC. probability for a nucleon with momentum 300-600 MeV/c to belong to np-SRC is ~18 times larger than to belong to pp-SRC. PRL 98,132501 (2007). dominant NN force in the 2N-SRC is tensor force. EVA / BNL and Jlab / HALL A Three nucleon SRC are present in nuclei. PRL 162504(2006); Science 320, 1476 (2008).

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