Significant change of the identified hadron compositions relevant to jet chemistry from p+p to Au+Au collisions at RHIC

The study of hadron spectra at high $p_{T}$ in p+p collisions provides a good test of perturbative quantum chromo-dynamic calculations (pQCD) and baseline for measurements of nuclear modification factors in Au+Au collisions. Using events triggered by the Barrel Electro-Magnetic Calorimeter, identified charged hadron transverse momentum ($p_T$) spectra are measured up to 15 GeV/$c$ at mid-rapidity ($\mid y\mid$ $ $ 5.5 GeV/c) for kaon are compared with that of pion in Au + Au collisions at 200 GeV.