Progress of the analysis on antiquark flavor asymmetry by the Drell-Yan experiment SeaQuest at Fermilab

Kei Nagai^1*

¹Institute of Physics, Academia Sinica, Taipei, Taiwan

* Presenter:Kei Nagai, email:knagai@gate.sinica.edu.tw

The SeaQuest experiment aims at measuring the antiquark flavor asymmetry in the proton: dbar/ubar.
We use the 120 GeV proton beam, which is provided by Fermilab Main Injector, and liquid hydrogen and deuterium targets to induce the Drell-Yan process. The final state di-muons are detected to extract the ratio of proton-deuteron to proton-proton Drell-Yan process cross sections, which is approximately proportional to the dbar/ubar.

The amount of anti-u and that of anti-d quarks in the proton were assumed to be the same based on the flavor symmetry, which was arisen from the flavor-independent coupling constant of the strong interaction. However, the NMC, NA51 and E866 experiments found the dbar is dominant in the proton. In particular, dbar/ubar is as asymmetric as 1.7 at Bjorken x ~ 0.2. SeaQuest extends the measurement of the dbar/ubar precisely into higher Bjorken x region (0.15 < x < 0.45).

Discrepancy is found between the E866 data and our preliminary results released in 2016 on the measurement of x>0.24. Significant efforts are spent for further investigation. In this talk, we will report the progress and address the plan for the final results.

Keywords: Drell-Yan process, QCD, Hadron Physics, Fermilab, PDFs