Un-ki Yang, Manchester 1 Nuclear Effects in Electron Scattering Arie Bodek University of Rochester Un-ki Yang University of Manchester NuFact 2008, Valencia, Spain, Jun 30 - July 5, 2008

Un-ki Yang, Manchester 2 Nuclear Effect in Electron Scattering  Of theoretical interest Shadowing Binding Fermi motion  exp. (osc. / non-osc.) with all heavy targets wants:  (A)  (A)/  (d)  This is what electron data can offer using with light & heavy target as a good reference  (A)/  (d ): EMC effect

Un-ki Yang, Manchester 3 Neutrino Cross Sections  Quasi-Elastic / elastic (W=M):  + n  - + p by form factors  Resonance (low Q 2, W< 2):  + p  - + p +  by Rein and Seghal model (overlap with DIS)  Deep Inelastic Scattering:  + p  - + X by quark-parton model (non-pQCD effect, high x PDFs)  Describe DIS, resonance within quark-parton model: with PDFS, it is easy to convert  (e) into  ( )   ( ) for deuterium (d):  (d,e) Nuclear effect in d : d/u issue at high x   (A, ) =  (d, ) * [  (A,e) /  (d,e)] Good reference to study nuclear effect vs e, vector vs axial-vector, F 2 vs xF 3

Un-ki Yang, Manchester 4 Modeling on  (e) for p and d  Describe all processes, even photo-production (Q 2 =0) within quark-parton model  Challenge: High x PDFs (d/u) Non-pert. QCD at low Q 2 Nuclear effect in the deuterium? Resonance scattering in terms of quark-parton model? (duality) GRV F2 q

Un-ki Yang, Manchester 5 Unified Approach  NNLO pQCD +TM approach:describes the DIS and resonance data very well: A phenomenological HT from the NLO analysis: ~ NNLO pQCD term  Effective LO approach: (pseudo NNLO for MC) Use a LO PDFs with a new scaling variable to absorb TM, HT, higher orders m f =M* (final state) P=M q

Un-ki Yang, Manchester 6  Use GRV98 LO   w = [Q 2 +B ] / [ M (1+(1+Q 2 / 2 ) 1/2 ) +A]  Different K factors for valence and sea  Ksea = Q 2 /[Q 2 +Csea] Kval = [1- G D 2 (Q 2 ) ] *[Q 2 +C 2V ] / [Q 2 +C 1V ], G D 2 (Q 2 ) = 1/ [ 1+Q 2 / 0.71 ] 4 (separate u, d val. ?)  Freeze the evolution at Q 2 = 0.8  Very good fits are obtained using SLAC/NMC/BCDMS p, d with low x HERA/NMC F 2 A=0.418, B=0.222, Csea = C 1V = 0.604, C 2V =  2 /DOF= 1268 / 1200 Fit with  w DIS F 2 (d)

Un-ki Yang, Manchester 7 F 2 (d) resonance Photo-production (p)  -proton) = 4  Q 2 * F 2 (  w, Q 2 ) where F 2 (  w, Q 2 ) = Q 2 /(Q 2 +C) * F 2 (  w ) Resonance and photo-production data Not included in the fit

Un-ki Yang, Manchester 8 DIS at low x

2xF 1 data?  All DIS F 2 at high/low x e/  data are well described  Photo-production data ( Q 2 =0) also work: thus i ncluded in the latest fit  2xF1 data (Jlab/SLAC) also work: using F 2 (  w)+R1998

Comparison with high E ( ) data  Assume vector = axial  Apply nuclear corrections using e/  scattering data  Use R=Rworld fit for 2xF 1  But total  (anti-neutrino) appear to be higher by 5%, xF 3 issue?  (  w) ----  (x ) E = 55 GeV

Un-ki Yang, Manchester 11 NLO Correction to xF 3 ?  Scaling variable,  w absorbs higher order effect on F 2  Higher order effect on F 2 and xF 3 : not same  Check double ratio => not 1 but indep. of Q 2 NLO VFS

Un-ki Yang, Manchester 12 NLO Correction to xF 3   (anti-neutrino): up by 3% while  (neutrino): down by 1% for all energy range.

Un-ki Yang, Manchester 13 Nuclear Effect in Electron Scattering  (A)/  (D ): EMC effect  Nuclear effect (x) in DIS at high Q 2:  Do we see the same nuclear effect(x) in the resonance region?  Jlab data: yes but using Nachtmann variable  x F2F2

Un-ki Yang, Manchester 14 Nuclear effect in Resonance and DIS  Comparison of resonance (JLAB) & DIS (SLAC/NMC) Good agreement in  carboniron

Un-ki Yang, Manchester 15 A-dependence of Nuclear Effect  Is nuclear effect scaled up with A number?  Carbon and 4 He Jlab data results favor density dep. nuclear effect Need to be careful about non-iso target correction 4 He 12 C

Un-ki Yang, Manchester 16 Nuclear Effect in the Deuterium?  Nuclear effect in d can be 4%, extrapolated using nuclear density Agree with Melinichouk & Thomas calculation Consistent with all DIS wit h all DIS e/  F 2, Tevatron W asym.  Correlated with d/u issue PRL 1998 Bodek-Yang

Un-ki Yang, Manchester 17 d/u at high x  Large change in d/u at high x due to nuclear effect in d Larger impact on  (d, ) Same conclusion from Thomas &, Mel. and CTEQ in 1998  Indep. measurements need; HERA CC (e - /e + ) Tevatron W asym. at high-  with larger lepton pt cut or LHC? Jlab measure of nearly on-shell n by tagging slow p: ed->epX?  Interesting results from NuTeV and E866 DY data: See Morfin’s talk NuTeV: u+d (higher?) E866 DY: 4u+d (lower?)

Un-ki Yang, HQL Dedicated efforts to prove d/u at high x from Jlab (reference)  Measure SF of nearly on-shell n by detecting slow spectator p in semi-inclusive ed -> ep X reaction : JLab CLAS++, BONUS exp. (almost scattering off free nucleon)  Parity violation in DIS on 1 H: very sensitive to d/u

Un-ki Yang, Manchester 19 Summary and Discussions  Effective LO model with  w describe all DIS and resonance data as well as photo-production data: Provide a good reference for  (,d) With  (A)/  (d) from e/ , provide  (,A),  (A)/  (d) for ; any deviation => different nuclear effect (vector vs axial: valence vs sea) in scattering   (A)/  (d) from e/  Scaling with Nachtman variable,  regardless of DIS and resonance Favors scaling with nucleon density, instead of A  Need to understand nuclear effect in d or d/u at high x  More Jalb data are coming, and neutrino data are absolutely needed (K2K, SciBooNE, MiniBooNE, and Minerva etc)

Un-ki Yang, Manchester 20 Nuclear effect from Jlab (backup)