Photoproduction of dileptons, photons, and light vector mesons in ultrarelativistic heavy ion collisions

We calculate the production cross section for dileptons, photons, and light vector mesons ($\rho ,\omega$, and $\varphi$) produced by the photoproduction processes in relativistic heavy ion collisions. The jet-quenching effects for fragmentation processes with $p_T>2\mathrm{GeV}$ and the jet-medium interaction with $p_T>4\mathrm{GeV}$ for the fast jets passing through the quark-gluon plasma in Pb-Pb collisions are also considered. The numerical results of photoproduction processes can improve the contribution of dileptons, photons, and light vector meson production in $p-p$ and Pb-Pb collisions at Large Hadron Collider energies.

Figure 1

(a) The invariant cross section of large-$p_T$ dilepton production for $p-p$ collisions at $\sqrt{s}=7.0\mathrm{TeV}$. The dashed line (dark yellow) is for the initial parton hard scattering processes [leading order (LO)], the dotted line (red) is for the semielastic photoproduction processes [semi.(dir.+res.)], the dashed-dotted line (blue) is for the inelastic photoproduction processes [inel.(dir.+res.+dou.)], the dashed-dotted-dotted line (dark cyan) is for the fragmentation dileptons produced by semielastic photoproduction processes [semi.(dir+res)-fra.], the short-dashed line (magenta) is for the fragmentation dileptons produced by inelastic photoproduction [inel.(dir+res+dou)-fra.], and the solid line (black) is for the sum of the above processes. (b) The same as panel (a) but for $p-p$ collisions at $\sqrt{s}=14.0\mathrm{TeV}$.

Figure 2

(a) The invariant cross section of large-$p_T$ dilepton production for Pb-Pb collisions at $\sqrt{s}=2.76\mathrm{TeV}$. The dashed line (dark yellow) is for the initial parton hard scattering processes (LO), the dotted line (red) is for the semielastic photoproduction processes [semi.(dir.+res.)], the dashed-dotted line (blue) is for the inelastic photoproduction processes [inel.(dir.+res.+dou.)], the dashed-dotted-dotted line (dark cyan) is for the fragmentation dileptons produced by semielastic photoproduction processes [semi.(dir+res)-fra.], the short-dashed line (magenta) is for the fragmentation dileptons produced by inelastic photoproduction [inel.(dir+res+dou)-fra.], and the solid line (black) is for the sum of the above processes. (b) The same as panel (a) but for Pb-Pb collisions at $\sqrt{s}=5.5\mathrm{TeV}$.

Figure 3

(a) The dilepton yield for Pb-Pb collisions with $\sqrt{s}=2.76\AA \mathrm{TeV}$. The dashed line (dark yellow) is for the thermal dilepton, the dotted line (red) is for the jet-dilepton conversion from the initial parton hard scattering processes, the dashed-doted line (blue) is for the jet-dilepton conversion from the inelastic photoproduction processes, the dashed-dotted-dotted line (dark cyan) is for the jet-dilepton conversion from the semielastic photoproduction processes, the short-dashed line (magenta) is for the Drell-Yan processes, and the solid line (black) is the sum of all the above processes. (b) The same as panel (a) but for Pb-Pb collisions at $\sqrt{s}=5.5\AA \mathrm{TeV}$.

Figure 4

(a) The invariant cross section of large-$p_T$ photon production for $p-p$ collisions at $\sqrt{s}=7.0\mathrm{TeV}$. The dashed line (dark yellow) is for the initial parton hard scattering processes (LO), the dotted line (red) is for the semielastic photoproduction processes [semi.(dir.+res.)], the dashed-dotted line (blue) is for the inelastic photoproduction processes [inel.(dir.+res.+dou.)], the dashed-dotted-dotted line (dark cyan) is for the fragmentation dileptons produced by semielastic photoproduction processes [semi.(dir+res)-fra.], the short-dashed line (magenta) is for the fragmentation dileptons produced by inelastic photoproduction [inel.(dir+res+dou)-fra.], and the solid line (black) is for the sum of the above processes. (b) The same as panel (a) but for $p-p$ collisions at $\sqrt{s}=14.0\mathrm{TeV}$.

Figure 5

(a): The direct photon production in Pb-Pb collisions with $\sqrt{s}=2.76\AA \mathrm{TeV}$. The data points are from the ALICE Collaboration [2], the dashed line (dark yellow) is for the initial parton hard scattering processes (LO), the short-dashed line (magenta) is for the direct photons from photoproduction processes, and the solid line (black) is the sum all the above processes. (b) The fragmentation photon production in Pb-Pb collisions with $\sqrt{s}=2.76\AA \mathrm{TeV}$. The dashed line (dark yellow) is the initial parton hard scattering processes (LO), the dashed-dotted-dotted line (dark cyan) is for the semi-inelastic photoproduction processes, the short-dashed line (magenta) is for the inelastic photoproduction processes, and the solid line (black) is the sum. (c) The real photon production in Pb-Pb collisions with $\sqrt{s}=5.5\AA \mathrm{TeV}$. The dashed line (dark yellow) is for the initial parton hard scattering processes (LO), the dotted line (red) is for the semielastic photoproduction processes [semi.(dir.+res.)], the dashed-dot line (blue) is for the inelastic photoproduction processes [inel.(dir.+res.+dou.)], the dashed-dotted-dotted line (dark cyan) is for the fragmentation dileptons produced by semielastic photoproduction processes [semi.(dir+res)-fra.], the short-dashed line (magenta) is for the fragmentation dileptons produced by inelastic photoproduction [inel.(dir+res+dou)-fra.], and the solid line (black) is for the sum of the above processes.

Figure 6

(a) The photon yield for Pb-Pb collisions with $\sqrt{s}=2.76\AA \mathrm{TeV}$. The dashed line (dark yellow) is for the jet-photon conversion from the initial parton hard scattering processes, the dashed-dotted line (blue) is for the jet-photon conversion from the semielastic photoproduction processes, the dashed-dotted-dotted line (magenta) is for the jet-photon conversion from the inelastic photoproduction processes, and the solid line (black) is the sum of all the above processes. (b) The same as panel (a) but for Pb-Pb collisions at $\sqrt{s}=5.5\AA \mathrm{TeV}$.

Figure 7

(a) The invariant cross section of $\rho$ meson production for $p-p$ collisions at $\sqrt{s}=7.0\mathrm{TeV}$. The dashed line (dark yellow) is for the initial parton hard scattering processes (LO), the dotted line (red) is for the semielastic photoproduction processes [semi.(dir.+res.)], the dashed-dotted line (blue) is for the inelastic photoproduction processes [inel.(dir.+res.+dou.)], the dashed-dotted-dotted line (dark cyan) is for the $\rho$ meson produced by semielastic photoproduction fragmentation processes [semi.(dir+res)-fra.], the short-dashed line (magenta) is for the $\rho$ meson produced by inelastic photoproduction fragmentation processes [inel.(dir+res+dou)-fra.], and the solid line (black) is for the sum of the above processes. (b) The same as panel (a) but for $\omega$ meson production. (c) The same as panel (a) but for $\varphi$ meson production.

Figure 8

The same as Fig. 7 but for the light vector meson production in $p-p$ collisions with $\sqrt{s}=14.0\mathrm{TeV}$.

Figure 9

(a) The invariant cross section of $\rho$ meson production for $p-p$ collisions at $\sqrt{s}=7.0\mathrm{TeV}$. The dashed line (dark yellow) is for the initial parton hard scattering processes (LO), the dotted line (red) is for the semielastic photoproduction processes [semi.(dir.+res.)], the dashed-dotted line (blue) is for the inelastic photoproduction processes [inel.(dir.+res.+dou.)], the dashed-dotted-dotted line (dark cyan) is for the $\rho$ meson produced by semielastic photoproduction fragmentation processes [semi.(dir+res)-fra.], the short-dashed line (magenta) is for the $\rho$ meson produced by inelastic photoproduction fragmentation processes [inel.(dir+res+dou)-fra.], and the solid line (black) is for the sum of the above processes. (b) The same as panel (a) but for $\omega$ meson production. (c) The same as panel (a) but for $\varphi$ meson production. The $\varphi$ meson data points are from the ALICE Collaboration [5].

Figure 10

The same as Fig. 9 but for the light vector meson production in Pb-Pb collisions with $\sqrt{s}=5.5\AA \mathrm{TeV}$.

Figure 11

(a) The $\rho$ meson yield for Pb-Pb collisions with $\sqrt{s}=2.76\AA \mathrm{TeV}$. The dashed line (dark yellow) is for the jet-medium interaction that the jet produced by the initial parton hard scattering processes, the dashed-dotted line (blue) is for the jet-medium interaction that the jet produced by the semielastic photoproduction processes, the dashed-dotted-dotted line (magenta) is for the the jet-medium interaction that the jet produced by the inelastic photoproduction processes, and the solid line (black) is the sum of all the above processes. (b) The same as panel (a) but for $\omega$ meson production. (c) The same as panel (a) but for $\varphi$ meson production.

Figure 12

The same as Fig. 11 but for the light vector meson production in Pb-Pb collisions with $\sqrt{s}=5.5\AA \mathrm{TeV}$.