Jet Tomography of Hot and Cold Nuclear Matter

TL;DR

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.

Abstract

Medium modification of parton fragmentation functions induced by multiple scattering and gluon bremsstrahlung is shown to describe the recent HERMES data in deeply inelastic scattering (DIS) very well, providing the first evidence of $A^{2/3}$-dependence of the modification. The energy loss is found to be $<dE/dL> \approx 0.5$ GeV/fm for a 10-GeV quark in a $Au$ nucleus. Including the effect of expansion, analysis of the $π^0$ spectra in central $Au+Au$ collisions at $\sqrt{s}=130$ GeV yields an averaged energy loss equivalent to $<dE/dL> \approx 7.3$ GeV/fm in a static medium. Predictions for central $Au+Au$ collisions at $\sqrt{s}=200$ GeV are also given.

Figures (3)

• Figure 1: Predicted nuclear modification of jet fragmentation function is compared to the HERMES data hermes on ratios of hadron distributions between $A$ and $D$ targets in DIS.
• Figure 2: Energy dependence of the nuclear modification compared with the HERMES data hermes.
• Figure 3: Calculated nuclear modification factor of $\pi^0$$p_T$ spectra for $d+Au$ and central $Au+Au$ collisions at $\sqrt{s}=130$ (solid) and 200 GeV (dashed) as compared to PHENIX data phenix (solid circles are measured spectra normalized by PHENIX parameterization of the $pp$ spectra while open circles are normalized by our calculated $pp$ spectra).