通过Pb$-$Pb和pp碰撞中修饰喷注子结构观测量关联探究喷注淬火
Probing jet quenching via the correlation of groomed jet substructure observables in Pb$-$Pb and pp collisions
AI总结：
通过测量pp和Pb-Pb碰撞中喷注劈裂角与动量共享分数的关联，发现Pb-Pb中喷注更窄且大开角非平衡喷注需包含弹性散射的HYBRID模型描述。
AI中文摘要：
本文报道了在质心能量$\sqrt{s_{\rm NN}}$ = 5 TeV的pp碰撞和0$-$10%中心Pb$-$Pb碰撞中，利用ALICE探测器对部分子簇射中第一次硬劈裂的劈裂角$\theta_{\rm g}$与动量共享分数$z_{\rm g}$之间关联的测量。带电粒子喷注采用anti-$k_{\rm T}$算法重建，喷注分辨参数$R$ = 0.2，横动量范围$60 \leq p_{\rm T,ch\\;jet} < 80$ GeV/$c$。使用Soft Drop修饰算法识别部分子簇射中的第一次劈裂。在Pb$-$Pb碰撞中观测到的喷注比pp碰撞中更窄。这种效应对于平衡喷注比非平衡喷注更显著。对于小开角的喷注，未观察到动量共享分数的显著改变。相反，有迹象表明，与pp碰撞相比，Pb$-$Pb碰撞中大开角喷注的横动量平衡性可能更差。$\theta_{\rm g}$与$z_{\rm g}$之间的关联在pp碰撞中由PYTHIA 8和POWHEG很好地描述，而HERWIG显示大开角喷注过少。在Pb$-$Pb碰撞中，该测量与多种模型进行了比较。该测量对介质响应的不同实现不敏感。包含弹性散射（如HYBRID模型中实现的）更受青睐，以描述Pb$-$Pb碰撞中具有大$\theta_{\rm g}$的非平衡喷注。然而，平衡喷注对弹性散射的敏感性较低。
英文摘要：
A measurement of the correlation between the splitting angle $θ_{\rm g}$ and the momentum-sharing fraction $z_{\rm g}$ of the first hard splitting in a parton shower in pp collisions and 0$-$10% central Pb$-$Pb collisions at $\sqrt{s_{\rm NN}}$ = 5 TeV with the ALICE detector is reported. Charged-particle jets are reconstructed using the anti-$k_{\rm T}$ algorithm with a jet resolution parameter $R$ = 0.2, in the transverse-momentum range $60 \leq p_{\rm T,ch\;jet} < 80$ GeV/$c$. The Soft Drop grooming algorithm is used to identify the first splitting in the parton shower. Jets observed in Pb$-$Pb collisions are narrower than in pp collisions. This effect is more pronounced for balanced than for unbalanced jets. No significant modification of the momentum-sharing fraction is observed for jets with small opening angles. In contrast, there is a hint that jets with a large opening angle may be less balanced in transverse momentum in Pb$-$Pb collisions compared to pp collisions. The correlations between $θ_{\rm g}$ and $z_{\rm g}$ are well described in pp collisions by PYTHIA 8 and POWHEG while HERWIG shows too few jets with large opening angle. In Pb$-$Pb collisions the measurement is compared to a variety of models. The measurement is insensitive to the different implementations of medium response. Inclusion of elastic scatterings, as implemented in the HYBRID model is preferred to describe the unbalanced jets with large $θ_{\rm g}$ in Pb$-$Pb collisions. The balanced jets, however, are less sensitive to elastic scatterings.
