近日，南开大学常雷团队揭开了介子第一激发态的内部结构。这一研究成果发表在2025年9月9日出版的《中国物理C》杂志上。

通过捕获介子激发态的Bethe-Salpeter幅值特征，研究组构建了一个代数模型，提供了介子第一激发态部分分布幅值和分布函数的总体特征。结果发现，在强子尺度下，激发态的分布振幅呈节点状，而分布函数是单峰的，在x=1/2处有一个峰值，价区有明显的凹凸起伏。这些发现为激发介子的部分子结构提供了新的见解，并对强子激发的理解有重要贡献。

附：英文原文

Title: Unveiling the Inner Structure of the Pion’s First Excited State

Author: Xiaobin Wang, Lei Chang

Issue&Volume: 2025-09-09

Abstract: By capturing the characteristics of the Bethe-Salpeter amplitude for the pion excitation state, we construct an algebraic model to provide the overall features of the pion’s first excitation state parton distribution amplitude and distribution function. We find that, at the hadronic scale, the distribution amplitude of the excited state exhibits nodes, while the distribution function is unimodal, with a peak at x=1/2 and distinct concave and convex fluctuations in the valence region. These findings provide new insights into the partonic structure of excited mesons and contribute significantly to our understanding of hadronic excitations.

DOI: 10.1088/1674-1137/adfc34

Source: http://hepnp.ihep.ac.cn/article/doi/10.1088/1674-1137/adfc34