Speaker
Dr
Sook Hyun Lee
(Iowa State University)
Description
The J/Psi, a bound state of charm and anti-charm quark with spin 1, decays into lepton pairs with a large branching ratios. Its production in polarized and unpolarized p+p collisions sheds light on different aspects of QCD. At RHIC energies, charmonium production in $p$+$p$ collisions is dominated by gluon-gluon interaction. As a result, measurements of the TSSA in polarized $p$+$p$ collisions are sensitive to initial state spin-momentum correlation effects such as gluon Qui-Sterman or tri-gluon correlation in collinear factorization and gluon Sivers effects in the transverse momentum dependent (TMD) formalism. Hadronization of charmonium in unpolarized $p$+$p$ collisions, is also accessible in more robust nonrelativistic QCD formalism due to the relatively large quark mass relative to the hadronization scale. Measuring how the spin of a decay lepton aligns with the spin of J/Psis can test and map out various production mechanisms. Recent results of forward and backward TSSA measurements for $p$+$p$,$p$+$Al$ and $p$+$Au$ collisions from PHENIX data taken at$\sqrt{s}$ =200 GeV in 2015 and the status of mid-rapidity and forward-rapidity measurements of the $J/\psi$ polarization for $p$+$p$ collisions from data taken at$\sqrt{s}$ =510 GeV in 2013 will be presented.
Primary author
Dr
Sook Hyun Lee
(Iowa State University)
