Whether quark- and gluon-initiated jets are modified differently by the quark-gluon plasma produced in heavy-ion collisions is a long-standing question that has thus far eluded a definitive experimental answer. A crucial complication for quark-gluon discrimination in both proton-proton and heavy-ion collisions is that all measurements necessarily average over the (unknown) quark-gluon composition of a jet sample. In the heavy-ion context, the simultaneous modification of both the fractions and substructure of quark and gluon jets by the quark-gluon plasma further obscures the interpretation. Here, we demonstrate a fully data-driven method for separating quark and gluon contributions to jet observables using a statistical technique called topic modeling. Assuming that jet distributions are a mixture of underlying “quark-like” and “gluon-like” distributions, we show how to extract quark- and gluon-jet fractions and constituent multiplicity distributions as a function of the jet transverse momentum. This proof-of-concept study is based on proton-proton and heavy-ion collision events from the Monte Carlo event generator Jewel with statistics accessible in Run 4 of the Large Hadron Collider. These results suggest the potential for an experimental determination of quark- and gluon-jet modifications.

中文翻译：

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重离子碰撞中数据驱动的夸克和胶子喷射改性

夸克和胶子引发的射流是否会因重离子碰撞中产生的夸克-胶子等离子体而有所不同，这是一个长期存在的问题，迄今为止还没有一个确切的实验答案。在质子-质子碰撞和重离子碰撞中，夸克-胶子区分的一个关键复杂因素是，所有测量值必须在喷射样品的（未知）夸克-胶子成分上平均。在重离子环境中，夸克-胶子等离子体对夸克和胶子射流的馏分和子结构的同时修饰进一步掩盖了这种解释。在这里，我们演示了一种完全数据驱动的方法，该方法使用称为主题建模的统计技术来分离夸克和胶子对喷射可观察物的贡献。假设射流分布是潜在的“类夸克”和“胶子状”分布的混合，我们展示了如何提取作为射流横向动量的函数的夸克和胶子射流分数以及组分多重分布。这项概念验证研究基于蒙特卡洛事件生成器的质子-质子和重离子碰撞事件在大强子对撞机的第4次运行中可以访问具有统计数据的珠宝。这些结果表明，有可能通过实验确定夸克和胶子喷射的改性。