论文标题
在$ \ sqrt {s _ {\ rm nn}} $ = 5.02 TEV中测量PP和PB-PB碰撞中的包含和领先的零件片段。
Measurement of inclusive and leading subjet fragmentation in pp and Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV
论文作者
论文摘要
本文通过在LHC的Alice实验中介绍了Jets在Proton-Proton（PP）和重离子碰撞中的碎片化特性的新测量。我们报告了Radius $ r $在Radius $ r $的喷气机中携带的横向动量的分数$ z_r $的分布。使用抗$ k _ {\ rm {t}} $算法在中期重建带电颗粒的喷气机，带有喷气半径$ r = 0.4 $，并通过使用anti-$ k _ {\ rm {\ rm { $ r = 0.2 $。在PP碰撞中，我们测量了包含和领先的征纸分布。我们将这些测量值与近代领先的对数准确度的扰动计算进行了比较，这表明阈值重新召集和强调对$ z_r $分布的影响很大。在重离子碰撞中，我们测量了领先的征射体分布，该分布可以访问与先前通过强子碎片分布对喷射淬灭的测量相比，允许使用更硬的喷射碎片化区域。 $ z_r $分布可以提取parton to-subjet碎片函数，并允许测试夸克 - 胶状等离子体（QGP）中喷气片段函数的通用性。与PP碰撞相比，我们发现PB-PB中$ z_r $分布没有显着修改。但是，正如几种喷气式淬火型号所预测的那样，分布也与$ z_r <0.95 $的硬化趋势一致。作为$ z_r \ rightarrow 1 $，我们的结果表明，任何这样的硬化效果都停止，从而使定性的新可能性揭示了竞争竞争的喷气淬火机制。通过将我们的结果与基于Parton到Jet碎片函数的独立提取的理论计算进行比较，我们发现与JET碎片的普遍性保持一致，并且在QGP中没有分解破裂的迹象。
This article presents new measurements of the fragmentation properties of jets in both proton-proton (pp) and heavy-ion collisions with the ALICE experiment at the LHC. We report distributions of the fraction $z_r$ of transverse momentum carried by subjets of radius $r$ within jets of radius $R$. Charged-particle jets are reconstructed at midrapidity using the anti-$k_{\rm{T}}$ algorithm with jet radius $R=0.4$, and subjets are reconstructed by reclustering the jet constituents using the anti-$k_{\rm{T}}$ algorithm with radii $r=0.1$ and $r=0.2$. In pp collisions, we measure both the inclusive and leading subjet distributions. We compare these measurements to perturbative calculations at next-to-leading logarithmic accuracy, which suggest a large impact of threshold resummation and hadronization effects on the $z_r$ distribution. In heavy-ion collisions, we measure the leading subjet distributions, which allow access to a region of harder jet fragmentation than has been probed by previous measurements of jet quenching via hadron fragmentation distributions. The $z_r$ distributions enable extraction of the parton-to-subjet fragmentation function and allow for tests of the universality of jet fragmentation functions in the quark-gluon plasma (QGP). We find no significant modification of $z_r$ distributions in Pb-Pb compared to pp collisions. However, the distributions are also consistent with a hardening trend for $z_r<0.95$, as predicted by several jet quenching models. As $z_r \rightarrow 1$ our results indicate that any such hardening effects cease, exposing qualitatively new possibilities to disentangle competing jet quenching mechanisms. By comparing our results to theoretical calculations based on an independent extraction of the parton-to-jet fragmentation function, we find consistency with the universality of jet fragmentation and no indication of factorization breaking in the QGP.
