Chun Yuen Tsang, Rongrong Ma, Prithwish Tribedy, Zhangbu Xu
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引用次数: 0
摘要
在组成夸克模型中,重子内部的每个价夸克都携带 1/3 单位的重子数。另一种情况是,胶子场 Y 形拓扑结构的中心(称为重子交界处)携带一个单位的重子数。在核碰撞中研究重子在大的速隙($\delta y$)上的输运为区分这两种图景提供了一种可能的工具。最近对Au+Au碰撞中净质子产率的全局数据进行的分析表明,指数依赖于$\delta y$,而且指数斜率不随事件中心性而变化,这有利于重子交界图景。由于结是味道盲的,超子--含有价奇异夸克的重子--预计会表现出与质子类似的行为。本研究旨在通过分析不同能量下 Au+Au 碰撞中的超子量来验证这一预言。我们观察到,在校正了陌生化产生的抑制之后,净超产率符合预期的指数形式。所提取的net-$\Lambda$、net-$\Xi$和net-$\Omega$的斜率参数在不确定性范围内与net-质子的斜率参数相互一致,而且没有中心依赖性,这进一步证实了重子交界图景。PYTHIA事件发生器的各种实施方案,主要是基于价夸克的重子输运,无法同时描述所有重子的斜率参数。
Beam energy dependence of net-hyperon yield and its implication on baryon transport mechanism
In the constituent quark model, each valence quark inside a baryon carries
1/3 unit of the baryon number. An alternative picture exists where the center
of a Y-shaped topology of gluon fields, called the baryon junction, carries a
unit baryon number. Studying baryon transport over a large rapidity gap
($\delta y$) in nuclear collisions provides a possible tool to distinguish
these two pictures. A recent analysis of global data on net-proton yield at
mid-rapidity in Au+Au collisions showed an exponential dependence on $\delta y$
and the exponential slope does not vary with event centrality, favoring the
baryon junction picture. Since junctions are flavor blind, hyperons -- baryons
containing valence strange quarks -- are expected to exhibit a similar behavior
as the proton. This study aims to test this prediction by analyzing hyperon
yields in Au+Au collisions at various energies. We observe that net-hyperon
yields, after correcting for the strangeness production suppression, adhere to
the expected exponential form. The extracted slope parameters for
net-$\Lambda$, net-$\Xi$ and net-$\Omega$ are consistent with each other and
with those of net-proton within uncertainties, and exhibit no centrality
dependence, further substantiating the baryon junction picture. Various
implementations of the PYTHIA event generator, primarily based on valence
quarks for baryon transport, are unable to simultaneously describe the slope
parameters for all baryons.