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Probing Parton Distribution Functions with Neutrinos

Probing Parton Distribution Functions with Neutrinos. Jorge G. Morfín Fermilab PDF’s in the 21st Century - Seattle, WA November, 2004. Outline. Which PDFs need help and where in x? Quarks at high-x Recent indications of more and less quarks at high-x? d/u

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Probing Parton Distribution Functions with Neutrinos

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  1. Probing Parton Distribution Functions with Neutrinos Jorge G. Morfín Fermilab PDF’s in the 21st Century - Seattle, WA November, 2004

  2. Outline • Which PDFs need help and where in x? • Quarks at high-x • Recent indications of more and less quarks at high-x? • d/u • How can Neutrinos help? • What can neutrinos tell us about nuclear PDFs? • An experiment to address these questions.

  3. CTEQ More Detailed Look at Higher x

  4. Comparison of three modern PDF global fits Djouadi & Ferrag, hep-ph/0310209

  5. Uncertainty in the Gluon DistributionNormalized to CTEQ6M Dashed - CTEQ5HJ Dotted - MRST01 Solid - CTEQ5M

  6. CTEQ uncertainties in u and d quark fitsTheory uncertainties NOT included

  7. d Quarks: not bad agreement Disregard the older results thanks to Wu-Ki Tung - MSU

  8. u Quarks: even better agreement … but this doesn’t mean we have it right! thanks to Wu-Ki Tung - MSU

  9. An indication that the valence quarks not quite right at high-x!E866 Preliminary Results (R. Towell - Hix2004) xbeam xtarget • xbeam distribution measures 4u + d as x--> 1. • Both MRST and CTEQ overestimate valence distributions as x --> 1 by 15-20%. • Radiative corrections have recently been calculated. (Not yet fully applied) • Possibly related to d/u ratio as x --> 1.

  10. Latest look at d/u… What’s going on at high-x? thanks to Wu-Ki Tung - MSU

  11. How do you measure d/u? Can be extracted from electroproduction p and n structure functions

  12. ! How do you measure F2n? Uncertainty from nuclear corrections to the deuteron

  13. Just to increase our confusion….Latest NuTeV s Compared to CCFR (currently in PDF fits)at High-x Indicates Effect Opposite to E866-no help for d/u V. Radescu - DIS04

  14. How do we Resolve the High-x Quark Dilemma? A clean and straightforward way to study high x quarks, including the d/u ratio, is with n / n - proton scattering

  15. We bring you the axial-vector current….

  16. Reverse for n Neutrino Structure Functionsn probe d, s, u, c while n probe u, c, d, s Reverse for n

  17. Ability to taste different quarks allows isolation of flavorsNeutrino - Proton Scattering At high x No messy nuclear corrections! F2np - xF3np = 4xu F2np + xF3np = 4xu

  18. Similar Expressions for Neutrino-Nucleus Scattering What Can We Learn With All Six Neutrino Structure Functions? Using Leading order expressions (for isoscalar target): Combining measured values in a given x-Q2 bin, for example

  19. 1.2 EMC NMC 1.1 E139 E665 1 0.9 0.8 0.7 0.001 0.01 0.1 1 Nuclear Effects - modified interaction probabilities S. Kumano Fermi motion valence-quark original EMC finding antiquark shadowing x sea quark valence quark EXPECTED to be different forn!!

  20. Difference between n-A and m-A nuclear effectsValence and Sea Quark nuclear effectsSergey Kulagin

  21. n How do we measure Neutrino-Nucleus/Proton Scattering?The MINERnA Experiment in the NuMI Beam at FermilabApproved by PAC in April C, Fe and Pb Nuclear targets Main Physics Topics with Expected Produced Statistics • Quasi-elastic 300 K events off 3 tons CH • Resonance Production 600 K total, 450 K 1p • Coherent Pion Production 25 K CC / 12.5 K NC • Nuclear Effects C:0.6M, Fe: 1M and Pb: 1 M • Pert/nonPert and Structure Functions 2.8 M total /1.2 M DIS event • Strange and Charm Particle Production > 60 K fully reconstructed events • Generalized Parton Distributions(few K events?)

  22. Both HEP and NP collaborators D. Drakoulakos, P. Stamoulis, G. Tzanakos, M. Zois University of Athens, Athens, Greece D. Casper University of California, Irvine, California E. Paschos University of Dortmund, Dortmund, Germany D. Boehnlein, D. A. Harris, M. Kostin, J.G. Morfin, P. Shanahan, P. Spentzouris Fermi National Accelerator Laboratory, Batavia, Illinois M.E. Christy, W. Hinton, C.E .Keppel Hampton University, Hampton, Virginia R. Burnstein, A. Chakravorty, O. Kamaev, N. Solomey Illinois Institute of Technology, Chicago, Illinois S.Kulagin Institute for Nuclear Research, Moscow, Russia I. Niculescu. G. .Niculescu James Madison University, Harrisonburg, Virginia G. Blazey, M.A.C. Cummings, V. Rykalin Northern Illinois University, DeKalb, Illinois W.K. Brooks, A. Bruell, R. Ent, D. Gaskell,, W. Melnitchouk, S. Wood Jefferson Lab, Newport News, Virginia S. Boyd, D. Naples, V. Paolone University of Pittsburgh, Pittsburgh, Pennsylvania A. Bodek, H. Budd, J. Chvojka, P. de Babaro, S. Manly, K. McFarland, I.C. Park, W. Sakumoto, R. Teng University of Rochester, Rochester, New York R. Gilman, C. Glasshausser, X. Jiang, G. Kumbartzki, K. McCormick, R. Ransome Rutgers University, New Brunswick, New Jersey H. Gallagher, T. Kafka, W.A. Mann, W. Oliver Tufts University, Medford, Massachusetts J. Nelson William and Mary College, Williamsburg, Virginia Red = HEP, Blue = NP, Green = Theorist

  23. After initial (parasitic to MINOS) run -would add a Liquid H2/D2(/O/Ar) TargetNOT YET APPROVED FOR THIS Technically easy/inexpensive to build and operate. Meeting safety specifications the major effort. Fid. vol: r = 80 cm. l = 150 cm. 350 K CC events in LH2 800 K CC events in LD2 2.5x1020 POT/yr he-n beam. H_2/D_2 MINOS Near ≈ Statistical Errors for .7 / 2 year of he-n / n xBj CH LH2 LD2 .6 - .65 0.6% 2.2% 1.5% .65 - .7 0.7 2.6 1.7 .7 - .75 1.0 3.7 2.5 .75 - .8 1.3 5 3 .8 - .85 2 7 5 .85 - .9 3 11 7 .9 - 1.0 4 14 10 Planes of C, Fe, Pb For part of run

  24. Measuring Six Structure Functions for Maximal Information on PDF’s + y2 FL R = Rwhitlow Neutrino 1 year he-beam Anti-Neutrino 2 years he-beam X = 0.1 - 0.125 Q2 = 2 - 4 GeV2 Kinematic cuts in (1-y) not shown (1-y)2

  25. Summary • Aside from low x gluon, PDFs fairly well established for x < 0.3-0.4. • For x > 0.3, uncertainty of the gluon grows dramatically. • The current fits for the valence u-quark is reasonable out to x = 0.5, while the d-quark uncertainty blows up around x = 0.3. • Both E866 and the latest NuTeV s results indicate a possible surprise for high-x u & d quarks…however in opposing directions! • d/u at high-x still uncertain due to spread in deuteron correction. • A CLEAN WAY TO MEASURE d/u: n/n + p SCATTERING! • The MINERnA Experiment at Fermilab, an NP + HEP collaboration, could make a high-statistics measurement of n + p scattering. • MINERnA will also provide the first detailed study of nuclear effects with n‘s including quark flavor-dependent nuclear effects.

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