Measurement of the light antiquark flavor asymmetry in the nucleon sea
- Texas A & M Univ., College Station, TX (United States)
A precise measurement made by Fermilab experiment E866 of the ratio of Drell-Yan yields from an 800 GeV/c proton beam incident on hydrogen and deuterium targets is reported. From this ratio of yields the asymmetry between anti-down and anti-up quark distributions in the nucleon is determined over a wide range in Bjorken-x. The x dependence of the ratio of $$\bar{d}$$(x) to $$\bar{u}$$(x) quarks shows a substantial excess of $$\bar{d}$$(x) with respect to $$\bar{u}$$(x) for x < 0:25. For x > 0:25 the data show the $$\bar{d}$$(x) to {anti u}(x) ratio to be much closer to unity. Predictions made by current nucleon structure parameterizations are shown to be in reasonable agreement with the measured asymmetry results below an x of 0.15, but are in sharp disagreement with the results at values of x higher than 0.2. These very same results and issues are discussed in brief in a recent paper [The E866 Collaboration, E. A. Hawker et al., Phys. Rev. Lett. 80, 3715 (1998)]. The asymmetry measurements are also shown to be able to support or reject several current theoretical models which aim to describe the nucleon sea as arising from nonperturbative QCD processes.
- Research Organization:
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- OSTI ID:
- 3120
- Report Number(s):
- FERMILAB-THESIS-1998-13; ON: DE00003120; TRN: US0204496
- Resource Relation:
- Other Information: TH: Thesis; Thesis information not supplied; PBD: 26 Jan 1999
- Country of Publication:
- United States
- Language:
- English
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