Probing the proton structure with Drell-Yan process and charmonium production at the SeaQuest experiment

High-mass dimuon production in $p + p$ and $p + d$ interactions have been measured in the SeaQuest experiment with the 120 GeV proton beam at Fermilab. The first result of the Drell-Yan $(p+d)/2(p+p)$ cross section ratio, based on the analysis of a fraction of the collected data, has provided new information on the light sea quark asymmetry. Analysis of the entire data set to extract the $\bar{d}/\bar{u}$ ratio is currently underway, and the status of this analysis will be reported. In addition to the Drell-Yan process, SeaQuest has also collected $J/\psi$ and $\psi(2S)$ production data, which are also sensitive to the gluon distributions in the nucleons and provide information complementary to that of the Drell-Yan data. Our measurement can also provide new insight into the underlying charmonium production mechanism.