Measurement of the Antiquark Flavor Asymmetry in the Nucleon Sea
Abstract
Description
A precise measurement of the ratio of Drell-Yan yields from an 800 GeV/c proton beam incident on liquid hydrogen and deuterium targets is reported. Over 370,000 Drell-Yan muon pairs were recorded. From these data, the ratio of anti-down ($\bar{d}$) to anti-up ($\bar{u}$) quark distributions in the proton sea is determined over a wide range in Bjorken-x. A strong x dependence is observed in the ratio $\bar{d}/\bar{u}$. From this result, the integral of $(\bar{d}-\bar{u})$ is evaluated for 0.015<x<0.35 and compared with deep inelastic scattering results. The origin of this asymmetry is probably due to non-perturbative effects such as those contained in pion cloud models. This measurement has instigated new global fits since previous parameterizations of the proton could not accommodate this large asymmetry.
Ph.D. Dissertation, 127 pages, 34 figures
Ph.D. Dissertation, 127 pages, 34 figures