Polarized and Unpolarized Drell-Yan Measurements at COMPASS.
Takahiro Sawada1*, Wen-Chen Chang1, Chia-Yu Hsieh1,2, Yu-Shiang Lian1,3, Yu-Sheng Teng1
1Institute of Physics, Academia Sinica, Nankang, Taiwan
2Department of Physics, National Central University, Taoyuan, Taiwan
3Department of Physics, National Kaohsiung Normal University, Kaohsiung, Taiwan
* presenting author:Takahiro Sawada, email:sawada@phys.sinica.edu.tw
The COMPASS experiment at CERN will start a new measurement on the nucleon structure via Drell-Yan (DY) reactions using a 190 GeV/c π- beam impinging into a transversely polarized NH3, unpolarized Al and W targets.

This first-ever polarized DY measurement will provide the insight into the transverse momentum dependent parton distribution functions (TMD PDFs) such as the Sivers and Boer-Mulders functions. The comparison of TMD PDFs from DY and semi-inclusive deep-inelastic scattering (SIDIS) processes for checking the predicted sign reversal will be an essential test/verification of the theoretical framework of perturbative QCD and TMD physics, pursuing both types of measurements with the same apparatus at COMPASS will be unique.

The unpolarized DY measurement will allow us to further enrich COMPASS DY physics program by studying, for example, longitudinally polarized virtual photons at large xp, violation of Lam-Tung relation at large pT, and the flavor dependence of the EMC effect.

The important features and status of this project will be introduced.


Keywords: Drell-Yan, Transverse Momentum Dependent Parton Distribution Functions (TMD PDFs)