Jet-dilepton conversion in expanding quark-gluon plasma

We calculate the production of large-mass dileptons from the jet-dilepton conversion in the expanding quark-gluon plasma at Relativistic Heavy Ion Collider and Large Hadron Collider (LHC) energies. The jet-dilepton conversion exceeds the thermal dilepton production and Drell–Yan process in the large-mass region of $3.9\mathrm{GeV}<M<5.8\mathrm{GeV}$ and $6.3\mathrm{GeV}<M<8.7\mathrm{GeV}$ in central $\text{Pb}+\text{Pb}$ collisions at $\sqrt{s_{NN}}=2.76$ and 5.5 TeV, respectively. We present the numerical solution of ideal fluid hydrodynamics. We find that the transverse flow leads to a rapid cooling of the fire ball. The suppression due to transverse flow appears from small to large mass, the transverse-flow effect becomes important at LHC energies. The energy loss of jets in the hot and dense medium is also included.

Figure 1

Hydrodynamical solution of the collective radial velocity for $200A$ GeV central $\text{Au}+\text{Au}$ collisions. The black contours in the ($r,t$) plane are the radial velocity contours, corresponding to velocities of 0.025, 0.05, 0.1, 0.2, and 0.3 from left to right. The initial temperature $T_i=370$ MeV and the initial time ${\tau }_i=0.26\text{fm}/c$, corresponding to the particle rapidity density $dN/dy=1260$.

Figure 2

Same as Fig. 1 but for cental $\text{Pb}+\text{Pb}$ collisions at $\sqrt{s_{NN}}=5500$ GeV. The initial temperature $T_i=845$ MeV and the initial time ${\tau }_i=0.087\text{fm}/c$, corresponding to the particle rapidity density $dN/dy=5624$.

Figure 3

The results of thermal dileptons produced from the QGP phase at RHIC and LHC energies. In central $\text{Au}+\text{Au}$ collisions at $\sqrt{s_{NN}}=200$ GeV, the initial temperature is $T_i=370$ MeV. In central $\text{Pb}+\text{Pb}$ collisions at $\sqrt{s_{NN}}=2.76$ TeV and 5.5 TeV, the initial temperature is $T_i=636$ MeV and $T_i=845$ MeV, respectively. The dashed line means the thermal dileptons produced from the QGP without transverse flow. The solid line means thermal dileptons produced from the expanding QGP with transverse flow.

Figure 4

Dileptons originating from the passage of the jets passing through the QGP at RHIC and LHC energies. Dashed line shows jet-dilepton conversion without the transverse flow; solid line shows jet-dilepton conversion with the transverse flow. The jet-energy loss is included.

Figure 5

Dilepton yield for central $\text{Au}+\text{Au}$ collisions at $\sqrt{s_{NN}}=200$ GeV. Solid line shows thermal dileptons produced from the expanding QGP; dashed line shows the Drell–Yan contribution; dash-dot line shows dileptons produced by the jet-dilepton conversion. The energy-loss and transverse-flow effects are considered.

Figure 6

Same as Fig. 5 but for central $\text{Pb}+\text{Pb}$ collisions at $\sqrt{s_{NN}}=2.76$ TeV.

Figure 7

Same as Fig. 5 but for central $\text{Pb}+\text{Pb}$ collisions at $\sqrt{s_{NN}}=5.5$ TeV.

Figure 8

Effect of jet-energy loss on the jet-dilepton conversion at RHIC and LHC energies. The solid lines include the jet-energy loss, while the dashed lines do not.