发表机构
University of Florida; University of Chicago; University of Notre Dame; Johannes Gutenberg-Universität Mainz（佛罗里达大学; 芝加哥大学; 圣母大学; 美因茨约翰内斯·古腾堡大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文计算标度律下全球宇宙弦网络的引力波谱，在红外和紫外区域分别解析和数值推导，并给出对称破缺标度与轴子质量平面上的约束与探针。
AI 中文摘要
我们计算了标度律状态下全球宇宙弦网络产生的引力波谱。该谱在弦关联长度处自然分为红外和紫外两部分。在红外部分，我们基于非连通段模型，从弦应力-能量张量的不等时关联子解析推导出谱，该模型首次推广到弦环。环的贡献可能相当于长弦的贡献，具体取决于环演化参数。在紫外部分，当关联长度以下的结构主导源时，我们开发了一种数据驱动方法，将该关联子形式与现有格点模拟中测得的瞬时辐射功率谱联系起来。预测的谱在红外部分随频率上升，满足$\Omega_{\rm GW}\propto k$和$k^{3}$，在紫外部分则变平为一个带有轻微对数倾斜的平台。两者之间的转折频率由戈德斯通玻色子（即轴子）的质量设定。将预测谱与当前数据和预期灵敏度进行比较，我们在对称破缺标度$f_a$和轴子质量$m_a$的平面上绘制了当前约束和未来探针。
英文摘要
We compute the gravitational wave spectrum produced by a global cosmic string network in the scaling regime. The spectrum naturally divides at the string correlation length into infrared and ultraviolet parts. In the infrared, we derive the spectrum analytically from the unequal-time correlator of the string stress-energy tensor within the unconnected segment model, which we generalize for the first time to string loops. The loop contribution can be comparable to that of long strings, depending on the loop evolution parameters. In the ultraviolet, where structure below the correlation length dominates the source, we develop a data-driven method that connects this correlator formalism to the instantaneous radiation power spectrum measured in existing lattice simulations. The predicted spectrum rises with frequency as $Ω_{\rm GW}\propto k$ and $k^{3}$ in the infrared, and flattens into a plateau with a mild logarithmic tilt in the ultraviolet. The turnover frequency between the two is set by the mass of the Goldstone boson, the axion. Confronting the predicted spectrum with current data and projected sensitivities, we map out current constraints and future probes in the plane of the symmetry-breaking scale~$f_a$ and the axion mass~$m_a$.
