"Figure 2-15" of "In-medium modification of dijets in PbPb collisions at $\sqrt{s_\mathrm{NN}} =$ 5.02 TeV"

Modifications to the distribution of charged particles with respect to high transverse momentum $(p_{\mathrm{T}})$ jets passing through a quark-gluon plasma are explored using the CMS detector. Back-to-back dijets are analyzed in lead-lead and proton-proton collisions at $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV via correlations of charged particles in bins of relative pseudorapidity and angular distance from the leading and subleading jet axes. In comparing the lead-lead and proton-proton collision results, modifications to the charged-particle relative distance distribution and to the momentum distributions around the jet axis are found to depend on the dijet momentum balance $x_{j}$, which is the ratio between the subleading and leading jet $p_{\mathrm{T}}$. For events with $x_{j} \approx 1$, these modifications are observed for both the leading and subleading jets. However, while subleading jets show significant modifications for events with a larger dijet momentum imbalance, much smaller modifications are found for the leading jets in these events.

本研究借助CMS探测器（CMS detector），探究了穿过夸克-胶子等离子体（quark-gluon plasma）的高横向动量（transverse momentum, $p_mathrm{T}$）喷注所对应的带电粒子分布的修正效应。我们通过相对赝快度（relative pseudorapidity）分箱内的带电粒子关联，以及相对于领头喷注与次领头喷注轴线的角距离，对质心系核子-核子碰撞能量$sqrt{s_{mathrm{NN}}}=5.02$太电子伏特下的铅-铅碰撞与质子-质子碰撞中的背对背双喷注展开分析。对比两类碰撞的实验结果后发现，带电粒子相对角距离分布以及喷注轴线周围的动量分布的修正效应，依赖于双喷行动量平衡量$x_j$——该物理量为次领头喷注与领头喷注的横向动量之比。对于$x_japprox1$的碰撞事件，领头喷注与次领头喷注均观测到了此类分布修正。然而，当双喷行动量失衡程度更大时，次领头喷注呈现出显著的分布修正，而此类事件中的领头喷注仅存在极微弱的修正效应。