Phys. Rev. Lett. 80, 3715–3718 (1998)Measurement of the Light Antiquark Flavor Asymmetry in the Nucleon SeaReceived 9 December 1997; revised 13 February 1998; published in the issue dated 27 April 1998 A precise measurement of the ratio of Drell-Yan yields from an 800GeV/c proton beam incident on hydrogen and deuterium targets is reported. Over 140 000 Drell-Yan muon pairs with dimuon mass Mμ+μ-≥4.5GeV/c2 were recorded. From these data, the ratio of antidown ( d̅ ) to antiup ( u̅ ) quark distributions in the proton sea is determined over a wide range in Bjorken x. A strong x dependence is observed in the ratio d̅ /u̅ , showing substantial enhancement of d̅ with respect to u̅ for x<0.2. This result is in fair agreement with recent parton distribution parametrizations of the sea. For x>0.2, the observed d̅ /u̅ ratio is much nearer unity than given by the parametrizations. © 1998 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevLett.80.3715
DOI:
10.1103/PhysRevLett.80.3715
PACS:
13.85.Qk, 14.20.Dh, 24.85.+p, 25.40.Ve
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