The Measurement of J/ψ Invariant Cross Section in P+P Collision at √S = 500 GeV at the Star Experiment
Te-Chuan Huang1*
1Department of physics, National Cheng Kung University, Tainan, Taiwan
* presenting author:Te-Chuan Huang,
The production mechanism of the J/ψ meson is still not fully understood even after the discovery about 40 years ago. There are several popular models for the J/ψ production used in high energy physics such as the Color Singlet Model (CSM), the Color Evaporation Model (CEM), the Color Octet Mechanism (COM), and the Color Glass Condensate (CGC) model. However, none of these models can describe the spectra from experiments well.
The Solenoid Tracker at RHIC (STAR) is one of the major experiments at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. It is a general purpose high energy nuclear physics detector. In 2013, a new sub-detector, Muon Telescope Detector, was installed about 63% of the full system and completely installed in 2014. It provides an excellent opportunity to study the J/ψ physics using the dimuon channel at the STAR experiment for the first time. Due to the less Bremsstrahlung radiation of muons, the dimuon decay channel may provide us cleaner J/ψ signals than the dielectron decay channel.
In this talk, I will present the measurement of the J/ψ invariant cross section using the dimuon decay channel. The results in the dimuon channel are consistent with the previous results in the dielectron channel in the overlap p_T region and have reasonable agreement with the CGC+NRQCD and the NLO NRQCD predictions in low p_T and high p_T regions, respectively.

Keywords: STAR experiment, MTD, J/psi, Quarkonium, Charmonium