8 October 2003 K. McFarland, Rochester 1 What Needs to Be Resolved? Functional form does not evolve correctly –from Q 0 of 12.6 GeV 2 to range of GeV 2 Strangeness not conserved (low x) Not global fit –with outside PDFs, d-quark distributions not adjusted for changes in s(x) Inclusive measurements fit to same PDFs with NLO cross- section that go into LO cross- section for dimuons Dimuon acceptance mildly inconsistent with data m c used isn’t best fit to dimuon data Nuclear corrections for proton PDFs handled consistently in two analyses? NuTeVCTEQ

8 October 2003 K. McFarland, Rochester 2 CTEQ “Lepton-Photon” Result Olness, Tung et alia [CTEQ] NLO/LO fit Small asymmetry, ~+10% (CTEQ NLO d-quark PDFs) –inconsistency with zero not claimed –uses inclusive data and dimuons Paper speculates about errors in NuTeV analysis –Strangeness not conserved at x below charm production threshold –Evolution not correct for assumed functional form –They are good points; do they matter?

Main findings of the CTEQ Dimuon Global Analysis pertaining to the Strangeness Asymmetry of the nucleon parton distributions (so far) The dimuon data sets do give the main constraints on s, sbar in the global analysis; The shape (width) of the parabola is a robust feature of all current global fits; The center of the parabola wanders by ~ 0.1 for different series of LM fits; A conservative estimate: -0.1 < [S - ]*100 < 0.5 ?  eff 2 vs. [S - ] for one series of LM fits The blue curve flops around in different series, hence is not a robust feature of the GA..

8 October 2003 K. McFarland, Rochester 4 Dimuon Data and Asymmetry x region of CTEQ asymmetry is covered by NuTeV dimuon data –so it’s all a question of interpretation… CTEQ Asymmetry NuTeV Dimuons

8 October 2003K. McFarland, Rochester5 Comparison of fit-B with data

8 October 2003K. McFarland, Rochester6 Comparison of fit-B with data

8 October 2003K. McFarland, Rochester7 Comparison of fit-B with data

8 October 2003K. McFarland, Rochester8 Comparison of fit-B with data

8 October 2003K. McFarland, Rochester9 Comparison of fit-B with data Ccfr

8 October 2003K. McFarland, Rochester10 Comparison of fit-B with data NuTeV

8 October 2003K. McFarland, Rochester11 Comparison of fit-B with data NuTeV -

8 October 2003K. McFarland, Rochester12 Comparison of fit-B with data Ccfr -

8 October 2003 K. McFarland, Rochester 13 What Needs to Be Resolved? Functional form does not evolve correctly –from Q 0 of 12.6 GeV 2 to range of GeV 2 Strangeness not conserved (low x) Not global fit –with outside PDFs, d-quark distributions not adjusted for changes in s(x) Inclusive measurements fit to same PDFs with NLO cross- section that go into LO cross- section for dimuons Dimuon acceptance mildly inconsistent with data m c used isn’t best fit to dimuon data Nuclear corrections for proton PDFs handled consistently in two analyses? NuTeVCTEQ

8 October 2003 K. McFarland, Rochester 14 Current NuTeV Status Have refit at NLO with total strangeness constraint of CTEQ See little change in net momentum difference –Still precise constraint. Still weakly negative –Panagiotis Spentzouris is here and can give details if desired Work is ongoing

8 October 2003 K. McFarland, Rochester 15 Summary on Strange Sea A 30% excess of strange momentum over anti-strange would explain the NuTeV sin 2  W NuTeV analysis is consistent with zero, weakly negative using “all-iron” internal PDFs –uncertainty of 5% with assumed functional forms CTEQ measurement favors +10% We need to sort this out, but it won’t “fix” the NuTeV sin 2  W