J/Psi Production in Ultra-Peripheral Collisions at STAR

Apr 13, 2016, 2:30 PM
SR4b (DESY Hamburg)


DESY Hamburg

Small-x, Diffraction and Vector Mesons WG5 Small-x and Diffraction


Dr William Schmidke (BNL)


In 2010, the STAR Collaboration collected a large sample of triggers for ultra-peripheral AuAu collisions. In this talk, I will present measurements from this sample of J/Psi production in association with neutrons from photonuclear breakup. Preliminary results for the cross section as a function rapidity and pT will be presented and compared to models; the large component at low pT demonstrates the coherent production of J/Psi off the Au nuclei. In 2015, STAR also collected a sample of J/Psi mesons in ultra- peripheral pp and pAu collisions, where the protons were transversely polarized. The final state proton(s) were measured in the STAR Roman Pot system, constraining the kinematics of the process. I will present the prospects for measuring the asymmetry of J/Psi production with this sample. A non-zero asymmetry would be the first measure of the generalized parton distribution E for gluons, which is connected with the orbital angular momentum of partons in the nucleon.

Primary author

Presentation materials