Towards detailed tomography of high energy heavy-ion collisions by $\gamma$-jet

Understand

Within a multi-phase transport (AMPT) model with string melting scenario, the transverse momentum imbalance between prompt photon and jet is studied in Pb+Pb collisions at $\sqrt{s_{_{\rm NN}}}$ = 2.76 TeV.

• Jet loses more energy in more central collisions due to strong partonic interactions between jet parton shower and partonic matter, which is more significant than due to hadronic interactions only.
• The hadronization and final-state hadronic interactions have little influences on the imbalance.
• The imbalance ratio $x_{j\gamma}$ is sensitive to both production position and passing direction of $\gamma$-jet, which provides an opportunity to do detail $\gamma$-jet tomography on the formed partonic matter by selecting different $x_{j\gamma}$ ranges.