Measurement of the light antiquark flavor asymmetry in the nucleon sea

Thesis/Dissertation · Sat Aug 01 04:00:00 EDT 1998

DOI:https://doi.org/10.2172/3120· OSTI ID:3120

Hawker, Eric Andrew ^[1]

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1. Texas A & M Univ., College Station, TX (United States); Fermilab

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 Energy Research (ER)
• OSTI ID: 3120
• Report Number(s): FERMILAB-THESIS--1998-13; ON: DE00003120
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ASYMMETRY
DEUTERIUM TARGET
FERMILAB
HYDROGEN
NUCLEONS
PROTON BEAMS
QUANTUM CHROMODYNAMICS
QUARKS