1. Eli Piasetzky Tel Aviv University, Israel Free neutron structure function Work done in collaboration with: L. B. Weinstein (ODU) D. Higinbotham, J. Gomez (JLab) O. Hen, R. Shneor (TAU) Newport News, VA, USA, April 2011 No ‘free’ neutron target (life time ~ 12 minutes)

2. d 4 He 12 C 56 Fe 197 Au 4%22%20%14% The ‘evolution parameter’ is the amount of 2N-SRC in nuclei The probability to find 2N-SRC in the nucleus

3. d distribution at large x Uncertainty due to nuclear effects Adapted from J. F. Owens talk in this conference

4. d distribution at large x Uncertainty due to nuclear effects Adapted from J. F. Owens talk in this conference

5. Toy models for large x Nucleon ModelF 2 n /F 2 p d/u SU(6)2/31/2 Scalar diquark1/40 pQCD (p↑ q↑)3/71/5 Proton Wavefunction (Spin and Flavor Symmetric) 11 110 )( 3 2 )( 3 1 )( 3 1 )( 18 1 )( 2 1     SS SSS uud d udu u up Adapted from J.P. Chen

6. EMC Slopes 0.35 ≤ X B ≤ 0.7 SRC Scaling factors X B ≥ 1.4 See previous talk by Or Hen Phys. Rev. Lett. 106, 052301, 2011

7. 0.079±0.06 Deuteron is not a free np pair SRC=0 free nucleons A EMC SRC bound to free n p pairs (as opposed to bound to deuteron) The slopes for 0.35 ≤ X B ≤ 0.7 Conclusion: One should not neglect the EMC effect using deuteron and proton data to extract free neutron properties Phys. Rev. Lett. 106, 052301, 2011

8. The free neutron DIS cross section

9. Gessman, Saito,Thomas,Annu. Rev. Nucl. Part. Sci. 1995. 45:337 Where is the ratio of cross sections for absorbing a longitudinal to that for a transverse photon. See talk by Patricia Solvignon

10. For 0.35 ≤ X B ≤ 0.7 The free neutron structure function SLAC Data, J. Arrington et al. JPG 36(2009)205005. Extracted from this work Fermi smearing using relativistic deuteron momentum density With medium correction Phys. Rev. Lett. 106, 052301, 2011

11. The free neutron structure function Compared to CT calculations SLAC Data, Preliminary calculation by :H. l. Lai, P. Nadolsky, J. Pumplin,.P.Yuan See talk by Heidi Schellman in this conference Fh07b / fh02c are CT10 / CT10W like Chebyshev fits See talk by J.Pumplin in this conference SU6 pQCD Scalar qq

12. Compared to CT calculations SLAC Data, Preliminary calculation by :H. l. Lai, P. Nadolsky, J. Pumplin,.P.Yuan Fh07b / fh02c are CT10 / CT10W like Chebyshev fits See talk by J.Pumplin in this conference SU6 pQCD Scalar qq The d / u ratio

13. Summary We employ a phenomenological procedure to extract the free F 2 n /F 2 p structure function ratio from proton and deuteron DIS. At large Bjorken x, we obtain a substantially different F 2 n /F 2 p ratio compared to using the standard smearing model to account for the Fermi motion of the nucleons in the deuteron. Better agreement with W charge and W lepton asymmetries. Narrow uncertainties in PDFs at large x due to nuclear effects in deuteron structure function. Sharpen theoretical understanding of nuclear modifications of nucleons in nuclei.

14. arXiv:1003.4497 [hep-ph] Phys. Rev. Lett. 106, 052301, 2011