SeaQuest
SeaQuest is a fixed-target experiment at Fermilab that measure the dimuon production from interaction of the 120 GeV proton beam on various targets.
My main work at SeaQuest is to extract the $\sigma_{pd}/2\sigma_{pp}$ Drell-Yan cross section ratio from the entire dataset.
The cross section ratio is particular useful in probing the light sea-quark asymmetry in the proton. At the leading-order,
the Drell-Yan process involves the annihilation of a quark and antiquark from the two colliding hadrons.
With a forward spectrometer, the acceptance dedicates that $x_{1}$ is usually larger than $x_{2}$, hence the $\sigma_{pd}/2\sigma_{pp}$ cross section ratio can be approximated as
$$ \frac{\sigma_{pd}}{2\sigma_{pp}}\approx \frac{1}{2}\left(1+\frac{\bar{d}(x_{2})}{\bar{u}(x_{2})}\right) $$One major challenge in the analysis is separating the Drell-Yan signal from the combinatorial background, for which I have implemented a new mass spectrum decomposition procedure using TFractionFitter. The results using this mass spectrum decomposition have been reported in here.
I have also worked on the extracting the charmonium production cross section from $p+p$ and $p+d$ interaction.
Unlike the Drell-Yan process which is mostly sensitive to the quark and antiquarks distributions, the charmonium production is also sensitive to the gluon distribution. At leading-order processes such as quark-antiquark annihilation and gluon fusion will contribute to charmonium production.