We determine the transverse system size of the initial non-equilibrium Glasma state and of the hydrodynamically evolving fireball as a function of produced charged particles in p+p, p+Pb and Pb+Pb collisions at the Large Hadron Collider. Our results are consistent with recent measurements of Hanbury-Brown-Twiss (HBT) radii by the ALICE collaboration. Azimuthal anisotropy coefficients v_n generated by combining the early time Glasma dynamics with viscous fluid dynamics in Pb+Pb collisions are in excellent agreement with experimental data for a wide range of centralities. In particular, event-by-event distributions of the v_n agree with the experimental data out to fairly peripheral centrality bins. In striking contrast, our results for p+Pb collisions significantly underestimate the magnitude and do not reproduce the centrality dependence of data for v_2 and v_3 coefficients. We argue that the measured v_n data and HBT radii strongly constrain the shapes of initial parton distributions across system sizes that would be compatible with a flow interpretation in p+Pb collisions. Alternately, additional sources of correlations may be required to describe the systematics of long range rapidity correlations in p+p and p+Pb collisions.
Initial state geometry and the role of hydrodynamics in proton-proton, proton-nucleus and deuteron-nucleus collisions
我们将成功的重离子碰撞的Monte Carlo Glauber和IP-Mehma初态模型应用于质子-质子、质子-核和氘-核碰撞中产生的小得多的系统。我们观察到一个显着更大的灵敏度的初始状态的几何形状，在这些模型中的多粒子生产的细节相比，核-核碰撞。特别是，我们发现，在p+A碰撞中产生的系统的大小是非常相似的p+p碰撞中产生的，并预测可比的Hanbury-Brown-Twiss半径在两个系统中没有流动。模型中计算的偏心率差异较大，而生成的流量系数v_2和v_3之间的差异较小。对于大量的质子-铅碰撞的参与者，在IP-Plumma模型中产生的v_2值与质子-质子碰撞中获得的值相当。在较小尺寸的系统中，对流动的粘性修正在特征寿命上是大的。相反，粘性的贡献显着减少了较长的时空演化的重离子碰撞。
Sensitivity of flow harmonics to sub-nucleon scale fluctuations in heavy ion collisions
本文采用一种新的平滑流体动力学初始能量密度的方法，证明了在核-核碰撞中，驱动末态流谐波$v_n$的初始空间偏心率$\varepsilon_{m,n}$对初始能量密度空间梯度的基本尺度$λ$的变化具有显著的鲁棒性。对于$\sqrt{s}=2.76$ TeV Pb+Pb碰撞，如果涨落的尺度从$0.1$变化到$1$ fm，则$\varepsilon_{m,n}$（跨中心性类）的变化小于$10\%$。我们表明，使用2+1拉格朗日流体动力学代码，v-USPhydro，这种鲁棒性被转移到最终的$v_n$的事件内计算事件粘性流体动力学。这表明核-核碰撞中的流谐波对限制尺度以下的潜在微观亚核子物理并不特别敏感。另一方面，顶部$1\%$高多重数$\sqrt{s}=5.02$ TeV p+Pb碰撞的偏心率被发现是非常敏感的亚核尺度的波动，这应该与具有相同的多重数的外围Pb+Pb碰撞中发现的鲁棒性形成对比。
v4 from ideal and viscous hydrodynamic simulations of nuclear collisions at the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC)
Sensitivity of anisotropic flow in Pb+Pb collisions to the neutron skin of $^{208}$Pb at energies available at the CERN Large Hadron Collider
University of Shanghai for Science and Technology（上海理工大学）；Institute of Modern Physics, Fudan University（复旦大学现代物理研究所）；Shanghai Research Center for Theoretical Nuclear Physics, NSFC and Fudan University（国家自然科学基金委与复旦大学理论核物理上海研究中心）
Probing $α$ clustering in $^{12}\mathrm{C}$ at energies available at the Cooling Storage Ring facility using the Jet AA Microscopic Transport Model
Institute of Modern Physics Chinese Academy of Sciences（中国科学院近代物理研究所）；State Key Laboratory of Heavy Ion Science and Technology, Institute of Modern Physics Chinese Academy of Sciences（中国科学院近代物理研究所重离子科学和技术国家重点实验室）
