title: Jet tomography of hot and cold nuclear matter.
abstract: Modification of parton fragmentation functions by multiple scattering and gluon bremsstrahlung in nuclear media is shown to describe very well the recent HERMES data in deeply inelastic scattering, giving the first evidence of the A(2/3) dependence of the modification. The energy loss is found to be <dE/dL> approximately 0.5 GeV/fm for a 10-GeV quark in an Au nucleus. Including the effect of expansion, analysis of the pi(0) spectra in central Au+Au collisions at sqrt[s]=130 GeV yields an averaged energy loss equivalent to <dE/dL> approximately 7.3 GeV/fm in a static medium. Predictions for central Au+Au collisions at sqrt[s]=200 GeV are also given.
authors.affiliation: Institute of Particle Physics, Huazhong Normal University, Wuhan 430079, China.
authors.forename: Enke
authors.initials: E
authors.lastname: Wang
authors.forename: Xin-Nian
authors.initials: XN
authors.lastname: Wang