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arXiv 1810.08306hep-ph
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PYTHIA和被占据的质子

PYTHIA and the preoccupied proton

Thomas A. Trainor

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10 pages, 7 figures, Proceedings of XLVIII International Symposium on Multiparticle Dynamics
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摘要：

Pythia Monte Carlo（PMC）已广泛应用于高能$p$ - $p$和$p$ - $\bar p$碰撞的模拟。PMC是基于几个假设，如大多数强子产生喷流（多部分子相互作用或MPI），$p$ - $p$中心性是相关的，颜色重联（CR）强烈影响碎片喷流。另一种描述是由强子产生的两组分（软+硬）模型（TCM）提供的。对$p$系综平均值- $p_t$数据的TCM分析显示，中心性趋势与通过基于程函近似的几何Glauber模型估计的趋势完全不同。Glauber估计的双星碰撞数是TCM估计的三倍。对$p$ -Pb数据的详细研究与Glauber的一个基本假设相冲突，即一个抛射质子可能同时与多个靶核子相互作用。相反，在$p$ - $p$和$p$ -A碰撞中，一旦启动，$p$ -N碰撞就排除了其它可能的相互作用（在该碰撞期间），并且在该碰撞中，任何一对参与部分子都可以相互作用--因此，$p$ -N碰撞是“全有或全无”.“在本报告中，PMC受到各种矛盾数据的挑战，并审查了$p$ -N排他性的证据，以证明标题中的“占据质子”。

英文摘要：

The PYTHIA Monte Carlo (PMC) has been applied broadly to simulations of high-energy $p$-$p$ and $p$-$\bar p$ collisions. The PMC is based on several assumptions, such as that most hadrons result from jet production (multiple parton interactions or MPIs), that $p$-$p$ centrality is relevant and that color reconnection (CR) strongly influences fragmentation to jets. An alternative description is provided by the two-component (soft + hard) model (TCM) of hadron production. TCM analysis of $p$-Pb ensemble-mean-$p_t$ data reveals centrality trends quite different from those estimated via a geometric Glauber model based on the eikonal approximation. Glauber estimates of binary-collision number are three times TCM estimates. Detailed study of $p$-Pb data conflicts with a basic Glauber assumption -- that a projectile proton may interact simultaneously with multiple target nucleons. Instead, in both $p$-$p$ and $p$-A collisions, a $p$-N collision once initiated is exclusive of other possible interactions (during that collision), and within the collision any pair of participant partons may interact -- a $p$-N collision is thus "all or nothing." In this presentation the PMC is challenged by an assortment of contradictory data, and evidence for $p$-N exclusivity is reviewed to make a case for the "preoccupied proton" of the title.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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