arXiv 2006.129182020-06-23hep-ph

质子-质子碰撞中重强子产生的一个新的部分子碎裂过程

A new parton fragmentation procedure for heavy hadron production in proton-proton collisions

Antoni Szczurek

备注：: 16 pages, 10 figures
DOI：: 10.1088/1361-6471/abc3d6

摘要：

我们提出了一个质子-质子碰撞中部分子-强子碎裂的新过程。在部分子-部分子质心系统中考虑强子化，假设强子在该坐标系中向出射部分子方向发射，然后利用相应的Lorentz变换将它们的四动量变换到整个质心系统中，并构造出合适的分布.对于重强子的产生，施加了能量-动量条件。在许多情况下，我们的过程不同意通常使用的规则，即产生的强子的速度是相同的父部分子的速度。我们用部分子产生的首阶方法说明了新提出的产生$D$介子、$Λ_c$重子和$η_c$夸克偶素的方案。给出了横动量、快度和Feynman- $x_F$分布。我们考虑$c \to D$和$g \to D$以及$c \to η_c$和$g \to η_c$强子化过程。由此得到的快度分布比传统的部分子-强子快度等价方法得到的快度分布窄得多。这对中快中子和前快中子都有影响，并可能对地球大气层中的高能中微子产生产生影响。我们还讨论了$c \to Λ_c^+$和$b \to Λ_c^+$片段化，并发现第二种机制可能是最近由ALICE合作观察到的$Λ_c^{\pm}$生产增强的部分原因。

英文摘要：

We propose a new procedure for parton-to-hadron fragmentation in proton-proton collisions. The hadronization is considered in the parton-parton center-of-mass system and hadrons are assumed to be emitted in the direction of outgoing partons in that frame and then their four-momenta are transformed to the overall center-of-mass system using relevant Lorentz transformations and appropriate distributions are constructed. For heavy hadron production the energy-momentum condition is imposed. In many cases our procedure disagrees with the commonly used rule that rapidity of produced hadron is the same as rapidity of the parent parton. We illustrate the newly proposed scheme for production of $D$ mesons, $Λ_c$ baryon and $η_c$ quarkonium in leading-order approach to parton production. The transverse momentum, rapidity and Feynman-$x_F$ distributions are shown. We consider $c \to D$ and $g \to D$ as well as $c \to η_c$ and $g \to η_c$ hadronization processes. The resulting rapidity distributions are much narrower than those obtained in the traditional approach with parton-hadron rapidity equivalence. This has consequences both for mid- and forward rapidities and could have consequences for high-energy neutrino production in the Earth's atmosphere. We discuss also $c \to Λ_c^+$ and $b \to Λ_c^+$ fragmentation and find that the second mechanism could be partly responsible for the enhanced production of $Λ_c^{\pm}$ observed recently by the ALICE collaboration.

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英文摘要：

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