High-p_T Hadron Spectra, Azimuthal Anisotropy and Back-to-Back Correlations in High-energy Heavy-ion Collisions

The observed suppression of high-$p_T$ hadron spectra, finite azimuthal anisotropy, disappearance of jet-like back-to-back correlations, and their centrality dependence in $Au+Au$ collisions at RHIC are shown to be quantitatively described by jet quenching within a pQCD parton model. The difference between $h^{\pm}$ and $\pi^0$ suppression in intermediate $p_T$ is consistent with the observed $(K+p)/\pi$ enhancement which should disappear at $p_T>6$ GeV/$c$. The suppression of back-to-back correlations is shown to be directly related to the medium modification of jet fragmentation functions(FF).