# XXVII International Workshop on Deep Inelastic Scattering and Related Subjects

Apr 8 – 12, 2019
Turin
Europe/Rome timezone

## J/psi polarization in $p$+$p$ collisions at PHENIX

Apr 10, 2019, 2:51 PM
17m
Rettorato - Aula Principi d'Acaja

### Rettorato - Aula Principi d'Acaja

via Verdi, 8 Turin
Parallel Session Talk WG6: Spin and 3D structure

sookhyun lee

### Description

The J/psi, a bound state of charm and anti-charm quark with spin 1 state, decays into spin ½ lepton pairs with a large branching ratio. Its production in $p$+$p$ collisions shed light on inner workings of charmonium production that is dominated by gluon-gluon interaction at RHIC energy. Hadronization of charmonium in unpolarized $p$+$p$ collisions is also accessible in robust nonrelativistic QCD formalism due to the large energy scale of heavy quark mass relative to the hadronization scale. Measuring how the spin of a decay lepton aligns with the spin of charmonium can test and map out various production mechanisms. In the past, the PHENIX saw non-sizable polarization in J/psi mesons produced in forward rapidity at $\sqrt{s}$ = 510 GeV and efforts continue to measure polarization at mid-rapidity. Status of mid-rapidity measurements of $J/\psi$ to decay di-electrons spin alignment for $p$+$p$ collisions from data taken at $\sqrt{s}$ = 510 GeV in 2013 will be presented.