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arXiv 1705.04558nucl-th
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LHC上Pb-Pb碰撞中粲夸克的强扩散效应对$J/ψ$产生的影响

Strong Diffusion Effect of Charm Quarks on $J/ψ$ Production in Pb-Pb collisions at the LHC

Jiaxing Zhao, Baoyi Chen

摘要:

我们在聚并模型的基础上研究了在$\sqrt{s_{NN}}$ = 2.76和5.02 TeV的Pb-Pb碰撞中$J/ψ$的产生。当碰撞能量从2.76 TeV增加到5.02 TeV时,粲偶数增加了50%以上。然而,包含$J/ψ$的核修饰因子$R^{5.02TeV}_{AA}/R^{2.76TeV}_{AA}$的比率仅为约1.1 $\sim$ 1.2。我们发现$J/ψ$的再生与粲夸克和反粲夸克的密度成正比,而不是与它们的总数成正比。夸克-胶子等离子体的强膨胀稀释了粲夸克密度,抑制了重夸克的结合几率和$J/ψ$再生。这种效应在碰撞能量较高的地方更为重要,因为那里QGP膨胀很强。我们还提出了比值$N_{J/ψ}/(N_D)^2$作为$c$和$\bar c$合并几率的度量,它只受QGP中重夸克扩散的影响,而不依赖于冷核物质效应和粲夸克产生截面等输入.在此基础上,给出了在未来圆形对撞机能量($\sqrt{s_{NN}}$ = 39 TeV)下的预测。

英文摘要:

We study the $J/ψ$ production based on coalescence model at $\sqrt{s_{NN}}$ = 2.76 and 5.02 TeV Pb-Pb collisions. With the colliding energy increasing from 2.76 TeV to 5.02 TeV, the number of charm pairs is enhanced by more than 50%. However, the ratio of $J/ψ$ inclusive nuclear modification factors $R^{5.02TeV}_{AA}/R^{2.76TeV}_{AA}$ is only about 1.1 $\sim$ 1.2. We find that the regeneration of $J/ψ$ is proportional to the densities of charm and anti-charm quarks, instead of their total numbers. The charm quark density is diluted by the strong expansion of quark gluon plasma, which suppresses the combination probability of heavy quarks and $J/ψ$ regeneration. This effect is more important in higher colliding energies where QGP expansion is strong. We also propose the ratio $N_{J/ψ}/(N_D)^2$ as a measurement of $c$ and $\bar c$ coalescence probability, which is only affected by the heavy quark diffusions in QGP, and does not depend on the inputs such as cold nuclear matter effects and cross sections of charm quark production. Further more, we give the predictions at the energy of Future Circular Collider ($\sqrt{s_{NN}}$ = 39 TeV).

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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