Tomography of high-energy nuclear collisions with photon-hadron correlations

Abstract

Within the next-to-leading order (NLO) perturbative QCD (pQCD) parton model, suppression of away-side hadron spectra associated with a high $p_T$ photon due to parton energy loss is studied in high-energy heavy-ion collisions. Dictated by the shape of the $\gamma$-associated jet spectrum in NLO pQCD, hadron spectra at large $z_T=p_T^h/p_T^{\gamma }\stackrel{>}{\sim }1$ are more sensitive to parton energy loss and therefore are dominated by surface emission of $\gamma$-associated jets, whereas small $z_T$ hadrons mainly come from fragmentation of jets with reduced energy which is controlled by the volume emission. These lead to different centrality dependence of the $\gamma$-hadron suppression for different values of $z_T$. Therefore, a complete measurement of the suppression of $\gamma$-triggered hadron spectra, including its dependence on the orientation of the $\gamma$-hadron pair with respect to the reaction plane, allows the extraction of the spatial distribution of jet quenching parameters, achieving a true tomographic study of the quark-gluon plasma in high-energy heavy-ion collisions.

4 pages in ReVTeX, 4 figures

References in corpus (6)

• Systematic Comparison of Jet Energy-Loss Schemes in a realistic hydrodynamic medium
• Dihadron Tomography of High-Energy Nuclear Collisions in NLO pQCD
• Measurement of direct photon production in p + p collisions at sqrt(s) = 200 GeV
• A systematic study of direct photon production in heavy ion collisions
• Direct photons from relativistic heavy-ion collisions
• Direct photon-charged hadron azimuthal correlations