Primary Submission Contact

Samuel Brandt

Faculty Sponsor

Jim Drachenberg

Faculty Sponsor Email Address


Arts and Sciences



Document Type

Poster Presentation


Fall 9-12-2014


Among the unanswered questions pertaining to nucleon spin physics is the origin of large azimuthal asymmetries (AN ) found in π forward pseudorapidity, η, from high-energy transversely polarized p + p collisions. One possible explanation is offered by twist-3 parton distribution and fragmentation functions. In order to test these and other mechanisms, it is important to study how the asymmetry changes over a range of pion kinematics. The STAR Endcap Electromagnetic Calorimeter (EEMC) is the only RHIC detector with the ability to study AN for π available at intermediate pseudorapidity, 0.8 ≤ η ≤ 2.0. STAR recently published the first measurement of AN for π using data collected in 2006 with collision energy √ STAR collected a high-statistics dataset with transverse beam polarization at √ s = 200 GeV. This offers over a five-fold increase in integrated luminosity relative to the 2006 dataset and a chance to enhance the precision of the previous results. The primary objective of this study is to determine the quality of the data from 2012 and to estimate the final statistical uncertainty.
Preliminary results from this study indicate a significant improvement over the 2006 results.

Additional Presentation Information

Wall Poster