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Neutrinos and Local Duality

Neutrinos and Local Duality. F. M. Steffens Mackenzie Uni. São Paulo – Brazil. Based on FMS,KT, PRD 70 094040 (2004). Our particular interest: The isoscalar F 2 n N neutrino Structure Function. At large x , we should have:.

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Neutrinos and Local Duality

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  1. Neutrinos and Local Duality F. M. Steffens Mackenzie Uni. São Paulo – Brazil Based on FMS,KT, PRD 70 094040 (2004)

  2. Our particular interest: The isoscalar F2nNneutrino Structure Function At large x, we should have: Similarly for the the isoscalar F2mNmuon Structure Function

  3. Test this using local duality A failure of this equality may imply: Unexpected strangeness at large x, perhaps intrinsic strange quarks Possible Charge symmetry breaking in the quark distributions Violation of local duality

  4. QCD justification for local duality: de Rùjula, Georgi, Politzer, PRD 4, 2901 (1977) Show that using the Nachtmann variable, the lower moments of F(x,Q2) are, actually, independent of Q2 The lower moments are the most important to reconstruct the x (or x) dependence of the structure functions Fres(x, Q2) ~ F(x)

  5. In reality, Fres(x, Q2) oscillates around the scaling function as the resonance poles are approached The oscillations come from higher twist contributions But they cancel on the average The scaling function is calculated at very high Q2: the resonance peaks have moved to the large x region

  6. The elastic part of the hadronic tensor for neutrino scattering

  7. Local Duality at the Nucleon Pole Nachtmann variable at the pion threshold Scaling Elastic Or and taking the dervivative we get...

  8. xth = Q2/(Q2 + mp (2M + mp )) Similarly:

  9. All put together: Calculated using a world data parametrization F2mN = (F2mp + F2mn)/2 KT, H. Kim, K. Saito, nu-th/0307013 M.J.Mussolf, T.W.Donelly, NPA 546 (92) 509 T.Kitagaki, PRD 38 (83) 436

  10. Q2 ~ 2.5 GeV2 W2 ~ 1.25 GeV2

  11. Some limitations: For x < 0.78, Q2 < 1 GeV2 Calculation should not be trusted Experimental uncertainty on the Elastic Form Factors around 10% at Q2 ~ 2 GeV2 (hep-ex/0308005) Local duality in general

  12. On the other hand, going the inverse way: WM, NPA 680, 52c (2000)

  13. How can we undestand our result? One possible contribution to our result could come from possible charge symmetry violation of quark distributions at large x. Using the charged ratio (CB,JTL,AWT,PRL81,4075 (1998)):

  14. From V. Barone, C. Pascaud, F. Zoner, EPJC 12, 243 (2000)

  15. In the large x region any contribution from antiquarks should be negligible. Hence, To match the calculation:

  16. Nuclear Corrections KT, KS, FMS, PLB 612, 5 (2005)

  17. Summary Local duality used to study the relation between the isoscalar structure functions as probed by neutrinos and muons Possible violation of charge symmetry in the valence distributions at very large x ? Violations of local duality for the elastic peak?

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