发表机构
University of Plymouth; Hiroshima University; Japan Atomic Energy Agency; The University of Osaka; Universidade Cidade de São Paulo (UNICID)（普利茅斯大学; 广岛大学; 日本原子能机构; 大阪大学; 圣保罗城市大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究在光前夸克模型下，结合QMC模型，系统研究了核物质中赝标量介子的分布振幅和部分子分布函数，发现介质效应显著修改介子结构，且与EMC效应定性相似。
AI 中文摘要
在本工作中，我们在光前夸克模型（LFQM）框架内，采用高斯和幂律（PL）波函数，对赝标量介子在核介质中的性质和内部结构进行了全面研究。我们将从夸克-介子耦合（QMC）模型获得的介质内夸克性质纳入LFQM，从而在夸克自由度方面提供了统一的描述。我们研究了对称核物质中π±、K±、D±和B±介子的分布振幅（DAs）和部分子分布函数（PDFs）。我们发现，演化后的介质内π介子DA和PDF在中间x处被强烈抑制，表明介质对介子结构产生了显著的修改。核物质中修改后的Gegenbauer系数a_n'、参数ξ以及DAs和PDFs的Mellin矩的符号和大小与其他理论预测一致。特别是，π介子DA的第二个Gegenbauer系数a_2^π随核密度显著增加，从真空中的0.096（0.057）增加到正常核密度下的0.232（0.202），分别对应高斯（PL）波函数。这一增加表明在核介质中π介子DA更宽且第二个Gegenbauer矩增强。我们进一步计算了π介子PDF比值R_{ρ/0}^{π}，发现其x依赖性表现出与观测到的欧洲μ子合作（EMC）效应定性相似的行为，突显了QCD演化在塑造介质修改的部分子结构中的重要作用。最后，我们将计算得到的自由空间π±和K±的DAs与可用的自由空间格点QCD结果进行比较，发现合理的一致性。
英文摘要
In this work, we present a comprehensive investigation of the in-medium properties and internal structure of pseudoscalar mesons within the light-front quark model (LFQM), employing both Gaussian and power-law (PL) wave functions. We incorporate in-medium quark properties obtained from the quark-meson coupling (QMC) model into the LFQM, thereby providing a unified description in terms of quark degrees of freedom. We investigate the distribution amplitudes (DAs) and parton distribution functions (PDFs) of $π^{\pm}$, $K^{\pm}$, $D^{\pm}$, and $B^{\pm}$ mesons in symmetric nuclear matter. We find that the evolved in-medium pion DA and PDF are strongly suppressed at intermediate $x$, indicating substantial medium-induced modifications to the meson structure. The signs and magnitudes of the modified Gegenbauer coefficients $a_n'$, the parameter $ξ$, and the Mellin moments of the DAs and PDFs in nuclear matter are found to be consistent with other theoretical predictions. In particular, the second Gegenbauer coefficient of the pion DA, $a_2^π$, increases substantially with nuclear density, from $0.096$ ($0.057$) in vacuum to $0.232$ ($0.202$) at normal nuclear density for the Gaussian (PL) wave function, respectively. This increase indicates a broader pion DA and an enhanced second Gegenbauer moment in the nuclear medium. We further calculate the pion PDF ratio $R_{ρ/0}^π$ and find that its $x$ dependence exhibits a behavior qualitatively similar to the observed European Muon Collaboration (EMC) effect, highlighting the important role of QCD evolution in shaping the medium-modified partonic structure. Finally, we compare the calculated free-space $π^{\pm}$ and $K^{\pm}$ DAs with available free-space lattice QCD results and find reasonable agreement.
Comments17 pages, 10 figures, 16 tables
