通过碎裂函数研究奇异强子候选态$f_0$(980)的内部结构
Internal structure of exotic hadron candidate $f_0$(980) by using fragmentation functions
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中文总结 AI 辅助
通过分析Belle合作组测量的$f_0$(980)碎裂函数，发现其内部构型随能量变化：低能下呈四夸克或$K\ar K$分子态，高能下呈$s\ar s$态，为奇异强子研究提供新视角。
中文摘要 AI 辅助
高能强子反应可能适合在奇异强子候选态中寻找奇异证据，而非依赖于质量、自旋、宇称和衰变宽度等全局观测量，因为夸克和胶子是显式的自由度。一种可能的方法是使用碎裂函数（FFs），利用其有利和不利函数的性质，这对应于部分子分布函数中的价夸克和海夸克分布。通过观察这些碎裂函数，我们应该能够发现奇异性质，因为价夸克分布反映了价组分的性质，正如在π介子和质子中所显示的那样。Belle合作组最近对$f_0$(980)碎裂函数的精确测量，使得通过观察其二阶矩和函数形式来发现其内部构型成为可能。$f_0$(980)碎裂函数的全局分析结果表明，其内部构型看起来像$s\ar s$，这与低能研究中提出的四夸克或$K\ar K$分子样构型不同。这一事实表明，内部构型随能量不同而不同。在低能下，它看起来像一个四夸克（$K\ar K$分子）强子，但在高能下，它看起来像一个$q\ar q$强子。类似地，一些奇异强子候选态在高能下可能变成普通的$q\ar q$或$qqq$强子，尽管它们在低能下被解释为奇异的。这种新想法应通过未来实验来检验，特别是通过观察高能强子反应中的能量或动量依赖性。
英文摘要
High-energy hadron reactions could be appropriate to find exotic evidences in exotic hadron candidates instead of global observables such as masses, spins, parities, and decay widths, because quarks and gluons are explicit degrees of freedom. One of possible methods is to use fragmentation functions (FFs) by taking advantage of properties on favored and disfavored functions, which corresponds to valence-quark and sea-quark distributions in parton distribution functions. Looking at these FFs, we should be able to find the exotic nature as the valence-quark distributions reflect the nature of valence constituents as shown in the pion and the proton. Recent accurate measurements of the $f_0$(980) FFs by the Belle collaboration made it possible to find its internal configuration by looking at their second moments and functional forms. Global analysis results of the $f_0$(980) FFs indicate that its internal configuration looks like $s\bar s$, which is different from a tetraquark or $K\bar K$-molecule like configuration suggested from low-energy studies. This fact indicates that the internal configuration looks different depending on the energy. At low energies, it looks like a tetraquark ($K\bar K$ molecule) hadron, but it looks like a $q\bar q$ hadron at high energies. In the similar way, some exotic hadron candidates could become ordinary $q\bar q$ or $qqq$ hadrons at high energies, although they are interpreted as exotic at low energies. This kind of new idea should be tested by future experiments especially by looking at energy or momentum dependencies in high energy hadron reactions.
