Measurement of the Light Antiquark Flavor Asymmetry in the Nucleon Sea

Journal Article · Wed Apr 01 00:00:00 EST 1998 · Physical Review Letters

OSTI ID:601035

Bush, J D; Isenhower, L D; Sadler, M E; Towell, R S; Willis, J L; Wise, D K ^[1]; Geesaman, D F; Kaufman, S B; Makins, N; Mueller, B A ^[2]; Brown, C N; Cooper, W E ^[3]; He, X C; Petitt, G ^[4]; Kaplan, D M ^[5]; Carey, T A; Garvey, G T; Lee, D M; Lee, W M; Leitch, M J ; McGaughey, P L; Moss, J M; Park, B K; Peng, J C; Reimer, P E; Sondheim, W E; Thompson, T N ^[6]; Kirk, P N; Wang, Y C; Wang, Z F ^[7]; Beddo, M E; Chang, T H; Kyle, G; Papavassiliou, V; Selden, J; Webb, J C ^[8]; Awes, T C; Stankus, P W; Young, G R ^[9]; Hawker, E A; Gagliardi, C A; Tribble, R E; Vasiliev, M A ^[10]; Koetke, D D; Nord, P M ^[11]

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1. Abilene Christian University, Abilene, Texas 79699 (United States)
2. Argonne National Laboratory, Argonne, Illinois 60439 (United States)
3. Fermi National Accelerator Laboratory, Batavia, Illinois 60510 (United States)
4. Georgia State University, Atlanta, Georgia 30303 (United States)
5. Illinois Institute of Technology, Chicago, Illinois 60616 (United States)
6. Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
7. Louisiana State University, Baton Rouge, Louisiana 70803 (United States)
8. New Mexico State University, Las Cruces, New Mexico 88003 (United States)
9. Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)
10. Texas A M University, College Station, Texas 77843 (United States)
11. Valparaiso University, Valparaiso, Indiana 46383 (United States)

A precise measurement of the ratio of Drell-Yan yields from an 800 GeV/c proton beam incident on hydrogen and deuterium targets is reported. Over 140000 Drell-Yan muon pairs with dimuon mass M{sub {mu}{sup +}{mu}{sup {minus}}}{ge}4.5 GeV/c{sup 2} were recorded. From these data, the ratio of antidown ({bar d} ) to antiup ({bar u} ) quark distributions in the proton sea is determined over a wide range in Bjorken x . A strong x dependence is observed in the ratio {bar d}/{bar u} , showing substantial enhancement of {bar d} with respect to {bar u} for x{lt}0.2 . This result is in fair agreement with recent parton distribution parametrizations of the sea. For x{gt}0.2 , the observed {bar d}/{bar u} ratio is much nearer unity than given by the parametrizations. {copyright} {ital 1998} {ital The American Physical Society}

• OSTI ID: 601035
• Journal Information: Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 17 Vol. 80; ISSN 0031-9007; ISSN PRLTAO
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ANTIPARTICLES
ASYMMETRY
DEUTERIUM TARGET
DRELL MODEL
FLAVOR
HYDROGEN 1 TARGET
NUCLEONS
PARTONS
PROTON BEAMS
PROTON REACTIONS
QUARKS