Azimuthal anisotropies of reconstructed jets in Pb + Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV in a multiphase transport model

Azimuthal anisotropies of reconstructed jets [$v_n^{\mathrm{jet}}(n=2,3)$] have been investigated in Pb + Pb collisions at the center of mass energy $\sqrt{s_{NN}}=2.76$ TeV within a framework of a multiphase transport (AMPT) model. The $v_2^{\mathrm{jet}}$ is in good agreement with the recent ATLAS data. However, the $v_3^{\mathrm{jet}}$ shows a smaller magnitude than $v_2^{\mathrm{jet}}$, and approaches zero at a larger transverse momentum. It is attributed to the path-length dependence in which the jet energy loss fraction depends on the azimuthal angles with respect to different orders of event planes. The ratio $v_n^{\mathrm{jet}}/{\varepsilon }_n$ increases from peripheral to noncentral collisions, and $v_n^{\mathrm{jet}}$ increases with the initial spatial asymmetry $\left({\varepsilon }_n\right)$ for a given centrality bin. These behaviors indicate that the $v_n^{\mathrm{jet}}$ is produced by the strong interactions between jet and the partonic medium with different initial geometry shapes. Therefore, azimuthal anisotropies of reconstructed jet are proposed as a good probe to study the initial spatial fluctuations, which are expected to provide constraints on the path-length dependence of jet quenching models.

Figure 1

$v_2^{\mathrm{jet}}$ as functions of $N_{\mathrm{part}}$ for four different jet $p_T$ bins in Pb + Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV, where open circles represent the AMPT results and solid circles represent the ATLAS experimental data [12, 13]. Some points are slightly shifted along the $x$ axis for better representation.

Figure 2

$v_n^{\mathrm{jet}}$ $(n=2$ and 3) as functions of $N_{\mathrm{part}}$ for jet $p_T$ bins of $45<p_T<60$ GeV/$c$ (a) and $60<p_T<80$ GeV/$c$ (b) in Pb + Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV, where open triangles represent $v_2^{\mathrm{jet}}$ with respect to ${\Psi }_2^r$, open circles represent $v_2^{\mathrm{jet}}$ with respect to ${\Psi }_{RP}$ = 0, open squares represent $v_3^{\mathrm{jet}}$ with respect to ${\Psi }_3^r$ and solid circles represent the ATLAS experimental data [12, 13]. Some points are slightly shifted along the $x$ axis for better representation.

Figure 3

The AMPT results for $v_2^{\mathrm{jet}}$ (a) and $v_3^{\mathrm{jet}}$ (b) as functions of $N_{\mathrm{part}}$ for the jet $p_T$ bin of $45<p_T<60$ GeV/$c$ for different evolution stages in Pb + Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV. Some points are slightly shifted along the $x$ axis for better representation.

Figure 4

The AMPT results on the jet energy loss fraction, $\Delta p_T/p{}_T$, as functions of $\Delta \varphi$ = ${\varphi }^{\mathrm{jet}}-{\Psi }_n^r$ [$n=2$ (solid circles) and 3 (open circles)] for the jet $p_T$ bins of $45<p_T<60$ GeV/$c$ (a) and $60<p_T<80$ GeV/$c$ (b) in the centrality bin of 20–30 % in Pb + Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV.

Figure 5

The AMPT results for $v_n^{\mathrm{jet}}/{\varepsilon }_n$ [$n=2$ (solid circles) and 3 (open circles)] as functions of $N_{\mathrm{part}}$ for the jet $p_T$ bin of $45<p_T<60$ GeV/$c$ in Pb + Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV. Some points are slightly shifted along the $x$ axis for better representation.

Figure 6

The AMPT results for $v_n^{\mathrm{jet}}$ as functions of ${\varepsilon }_n$ [$n=2$ (solid circles) and 3 (open circles)] for the jet $p_T$ bin of $45<p_T<60$ GeV/$c$ in the centrality bin of 20–30 % in Pb + Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV. Some points are slightly shifted along the $x$ axis for better representation.