近日，意大利比萨大学的Arsenii Titov及其研究团队取得一项新进展。经过不懈努力，他们成功求解无轴子的强CP问题。相关研究成果已于2024年8月27日在国际知名学术期刊《高能物理杂志》上发表。

该研究团队制定了自发CP破坏解决强CP问题的一般条件。夸克质量矩阵元是CP破坏序参量的多项式，其设计使得其行列式为实数常数。该方案仅允许有限数量的织构。这些条件可以在将CP作为无反常的局部味对称性的超对称理论中实现，为强CP问题和味之谜提供了一个统一的解决方案。

这一解决方案可以使用模不变性或局部U(1)对称性来实现。研究人员展示了模不变的实现，其中物质场被赋予小的模权重±2（±1），并利用了更高的能级N=2（N=3）。通常不需要重夸克，但其存在允许有色粒子填充味群的非单态表示形式的模型。

附：英文原文

Title: Solving the strong CP problem without axions

Author: Feruglio, Ferruccio, Parriciatu, Matteo, Strumia, Alessandro, Titov, Arsenii

Issue&Volume: 2024-08-27

Abstract: We formulate general conditions under which the strong CP problem is solved by spontaneous CP violation. Quark-mass matrix elements are polynomials in the CP-breaking order parameters, engineered such that their determinant is a real constant. This scheme permits only a limited number of textures. These conditions can be realized in supersymmetric theories with CP as an anomaly-free local flavor symmetry, suggesting a unified solution to the strong CP problem and the flavor puzzle. Our solution can be implemented using either modular invariance or a local U(1) symmetry. We present modular-invariant realizations where matter fields are assigned small modular weights ±2 (±1), utilising higher levels N = 2 (N = 3). Heavy quarks are in general not required, but their presence allows for models where colored particles fill non-singlet representations of the flavor group.

DOI: 10.1007/JHEP08(2024)214

Source: https://link.springer.com/article/10.1007/JHEP08(2024)214