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Experimental work on the CCFR/NuTeV neutrino experiments.

A Measurement of Differential Cross Sections in Charged-Current Neutrino Interactions on Iron and a Global Structure Functions Analysis. Un-Ki Yang Univ. of Rochester (currently, Univ. of Chicago) (CCFR-NuTeV Collaboration). Experimental work on the CCFR/NuTeV neutrino experiments.

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Experimental work on the CCFR/NuTeV neutrino experiments.

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  1. A Measurement of Differential Cross Sections in Charged-Current Neutrino Interactions on Iron and a Global Structure Functions Analysis Un-Ki Yang Univ. of Rochester (currently, Univ. of Chicago) (CCFR-NuTeV Collaboration) • Experimental work on the CCFR/NuTeV neutrino experiments. • Phenomenological studies with all deep inelastic scattering data. 4 Phys. Rev. Lett. 1 Eur. Phys J. C. 1 Phys. Rev. D Un-ki Yang, Univ. of Chicago

  2. Structure functions: QCD + PDFs for hadron collider Deep inelastic scattering • Low x region (0.01<x<0.1): • F2(n) & F2(m) have 10-20% discrepancy=>very large uncertainty in sea quarks. Tevatron p-p cross section is dominant. • d/u at high x (0.1<x<1) • Disagreement with CDF W asymm data =>poor understanding of d/u at high x • Important for precise measurements on W prod. at Tevatron, HERA and LHC • Very high x PDFS (x>0.7) • Only SLAC data (low Q2) available, but dominated by non-perturbative QCD effects • Crucial for high Q2 new physics at Tevatron, HERA, and LHC. • Neutrino scattering F2(n) = x[(u+u) + (d+d) + (s+s) ] xF3(n) = x[(u-u) + (d-d) ] • Charged-lepton (e, m) scattering • F2(p) = x[4/9(u+u) + 1/9(d+d) + 1/9(s+s) ] • F2(n) = x[4/9(d+d) + 1/9(u+u) + 1/9(s+s) ] • assuming dp = un Un-ki Yang, Univ. of Chicago

  3. Low x problem in F2 (0.01<x<0.1) CCFR(n) Discrepancy in F2 between neutrino & muon experiments (left) NMC(m) • Large pdf uncertainties at low x • …..many efforts from world… • R(long) effect: - Bodek-Rock-Yang model - CCFR R (PRL 87, 251802 (2001) • Iso-spin symm. violation(dp=un) (ruled out using CDF W asymm data) PRL 83, 2829 (2001) Bodek et al Finally, resolved it using Physics-Model-Independent extraction approach (right) PRL 86, 2742 (2001) Yang et al [CCFR] PRL 79, 1213 (1997) Seligman at al [CCFR] (no heavy charm, strange sea corrections) Un-ki Yang, Univ. of Chicago

  4. d/u problem at high x • A problem in d/u was indicated by the CDF W asymm. data and the NMC F2(d)/F2(p) data. • - large uncertainty in nuclear effects on deuterium • A significant change in d/u after nuclear binding correction on deuteron data • Excellent agreement with CDF W asymm. data • d/u -> 0.2 at x=1 (QCD prediction) • A high-pt jet rate is increased by 11%(evolution) • A large increase in the HERA CC high Q2 PRL 82, 2467 (1999) Yang and Bodek Un-ki Yang, Univ. of Chicago

  5. PDFs at high x? • Any additional valence quarks at very high x and low Q2 could produce a large increase to PDFs at high Q2 and intermediate x. • There are precise SLAC data, but not used by the MRS & CTEQ group, because of large non-perturbative QCD effects [ target mass effect, higher twist effects ] We find out that NLO pQCD + GP target mass + renomalon higher twist: describe the data very well. Very High x data ? PRL 82, 2467 (1999) Yang and Bodek Un-ki Yang, Univ. of Chicago

  6. NNLO pQCD + TM + Higher twist • Size of the higher twist effect with NNLO analysis is really small. • Most of the higher effects originate from the NNLO terms. • Estimation of the ratio of the NNLO and NLO PDFs indicates that the predctions fo the Z production will be increased by 2%. Develop a modified GRV94 LO PDFs for neutrino cross sections at high and low Q2 region (down to 0): hep-ex/0203009 Eur Phys J C13, 241 (2000) Yang and Bodek Un-ki Yang, Univ. of Chicago

  7. Very high x F2 proton data (DIS + resonance) NLO pQCD + TM + higher twist describes very high x DIS F2 and resonance F2 data well up to x=0.98 Good understanding of u quark dist. 10% uncertainty up to x=0.9 only 10-20% uncertainty at 0.9<x<0.98 Impact on searches for new physics at proton colliders PRL 82, 2467 (1999) Yang and Bodek Un-ki Yang, Univ. of Chicago

  8. Conclusion:Ready to use the nucleon as a tool in searching for new physics in hadron colliders? My deep appreciation to everyone!!! Supervisor: A. Bodek My dear CCFR-NuTeV colleagues [ M. Shaevitz, W. Smith, R. Bernstein et al, especially SF group (Seligman , Conrad)] + MRST / CTEQ groups + many others friends who have helped on my journey + Rochester + Chicago + Fermilab / DOE / NSF + perhaps Korean military too(?) + definitely, my Lord and family Un-ki Yang, Univ. of Chicago

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