近日，四川大学物理系的郭华忠及其研究小组取得一项新进展。经过不懈努力，他们揭示介子-介子散射长度的温度和体积依赖性。相关研究成果已于2024年2月15日在国际知名学术期刊《中国物理C》上发表。

该研究团队在Nambu-Jona-Lasinio模型的框架下，研究了有限温度和有限空间体积下s波介子-介子散射长度a₀和a₂。研究人员利用固有时间正则化方法研究了伪转变温度以外的行为。

结果显示，散射长度a₀在莫特温度附近表现出奇异性，a₂是温度的连续非单调函数。研究人员给出了有限体积对散射长度的影响，发现a₀可能为负值，并在小体积条件下其奇异性消失，这可能暗示手性相变随着体积的减小而存在。

附：英文原文

Title: Temperature and volume dependence of pion-pion scattering lengths

Author: Qing-Wu Wang, Hua-Zhong Guo

Issue&Volume: 2024-02-15

Abstract: The s-wave pion-pion scattering lengths a₀ and a₂ are studied at finite temperature and in finite spatial volume under the framework of the Nambu–Jona-Lasinio model. The behavior beyond the pseudo transition temperature is investigated using proper time regularization. The scattering length a₀ exhibits singularity near the Mott temperature, and a₂ is a continuous but non-monotonic function of temperature. We present the effect of finite volume on the scattering length and find that a₀ can be negative and its singularity disappears at small volumes, which may hint at the existence of a chiral phase transition with decreasing volume.

DOI: 10.1088/1674-1137/ad123f

Source: http://hepnp.ihep.ac.cn/article/doi/10.1088/1674-1137/ad123f