Speaker
Description
Naively, the amounts of $\bar{d}$ and $\bar{u}$ in the proton were expected to be the same based on the flavor-independence of the strong coupling.
However, the muon deep inelastic scattering experiment NMC at CERN found $\bar{d}>\bar{u}$ in the proton.
Drell--Yan experiments also obtained the results consistent with it.
The Drell--Yan experiment E866 at Fermilab showed that $\bar{d}(x)/\bar{u}(x)>1.0$ for $0.015 < x < 0.20$.
It also showed $\bar{d}(x)/\bar{u}(x)<1.0$ at large $x$ ($x\sim 0.3$), although it is consistent with 1.0 within statistical uncertainty.
SeaQuest is a Drell--Yan experiment at Fermilab, that measured the antiquark flavor asymmetry $\bar{d}/\bar{u}$ precisely in for a wide $x$ range ($0.13 < x < 0.45$) including the intriguing region from E866.
It uses a 120 GeV proton beam extracted from Fermilab Main Injector colliding with liquid hydrogen and deuterium targets.
The antiquark flavor asymmetry $\bar{d}(x)/\bar{u}(x)$ is derived from the cross section ratio of proton-deuterium to proton-proton Drell--Yan processes.
In this talk, the SeaQuest results of the $\bar{d}(x)/\bar{u}(x)$ analysis will be presented.
