"Figure 7-22" 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），对穿过夸克-胶子等离子体（quark-gluon plasma）的高横动量（transverse momentum，记为$p_mathrm{T}$）喷注相关的带电粒子分布修正效应展开了探究。针对$sqrt{s_mathrm{NN}}=5.02$ TeV的铅-铅碰撞与质子-质子碰撞事件，本研究通过带电粒子在相对赝快度区间内的关联，以及其与领头喷注、次领头喷注轴的角距离，对背对背双喷注开展了分析。对比两类碰撞的实验结果可知，带电粒子相对距离分布与喷注轴附近动量分布的修正效应，取决于双喷动量平衡量$x_j$——该量定义为次领头喷注与领头喷注的横动量之比。当$x_japprox1$时，领头喷注与次领头喷注均观测到此类修正效应。不过，在双喷动量失衡程度更大的事件中，次领头喷注会呈现出显著的修正效应，而这类事件中的领头喷注所受修正幅度则要小得多。