AI 中文总结
研究利用CMS探测器收集的铅铅碰撞数据及事件形状工程技术，通过不对称参数\(q_2\)研究\(D^0\)介子椭圆流与带电粒子椭圆流的相关性，发现初始状态几何形状对粲强子流发展有重大影响，并与模型计算比较。
AI 中文摘要
探索了高能重离子碰撞中初始状态几何形状对瞬发\(D^0\)介子椭圆流的影响。2018年用欧洲核子研究中心大型强子对撞机的CMS探测器收集了质心能量为5.02 TeV、积分亮度为0.607 nb\(^{-1}\)的铅铅数据样本。基于这些数据，采用事件形状工程技术分离具有相似几何性质的碰撞。首先从探测器前向区域的横向能量分布确定不对称参数\(q_2\)，它与近中快度处测量的包含带电粒子的椭圆各向异性线性相关。以带电粒子\(v_2\)系数为初始状态偏心率的代理，研究了近中快度处\(D^0\)介子\(v_2\)值与包含带电粒子\(v_2\)值的相关性。发现对于横向动量在2 - 30 GeV范围内的\(D^0\)介子以及不同碰撞重叠度，基于相似\(q_2\)区间选择时，\(v_2\)值与带电粒子的\(v_2\)值高度相关。这表明初始状态几何形状对重离子碰撞中粲强子流的发展有重大影响。将探索\(D^0\)介子和带电粒子热化及集体运动的模型计算与实验结果进行了比较。
英文摘要
The influence of the initial-state geometry on the elliptic flow of prompt D$^0$ mesons in high-energy heavy ion collisions is explored. A lead-lead (PbPb) data sample at a center-of-mass energy per nucleon pair of 5.02 TeV and with an integrated luminosity of 0.607 nb$^{-1}$ was collected in 2018 with the CMS detector at the CERN LHC. Based on these data, an event-shape engineering technique is used to isolate collisions with similar geometrical properties. An asymmetry parameter, $q_2$, is first determined from the distribution of transverse energy in the forward region of the detector. This parameter is shown to be linearly correlated with the elliptic anisotropy of inclusive charged particles measured near mid-rapidity, as characterized by the second-order Fourier coefficients, $v_2$. Taking the charged particle $v_2$ coefficients as proxies for the initial-state eccentricity, the correlation of D$^0$ meson $v_2$ values near mid-rapidity with those of inclusive charged particles is then studied. For D$^0$ mesons with transverse momenta in the range of 2$-$30 GeV and for different degrees of collision overlap, the $v_2$ values are found strongly correlated with those for charged particles when selected based on similar $q_2$ intervals. This correlation suggests that the initial-state geometry substantially impacts the development of charm-hadron flow in heavy ion collisions. A model calculation that explores the thermalization and collective motion of D$^0$ mesons and charged particles is compared to the experimental results.
CommentsThis version has an updated author list. Submitted to Physics Letters B. All figures and tables can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/HIN-24-015 (CMS Public Pages)
