AI 中文总结
研究正常双希格斯二重态模型中强一阶电弱相变及引力波，对比四种汤川类型和热重整化方案，发现参数空间有方法依赖性及不同限制，确定了能产生高信噪比引力波参数区域，凸显空间引力波观测与高能对撞机搜索的互补性。
AI 中文摘要
我们对具有软破缺\(Z_2\)对称性的\(CP\)守恒双希格斯二重态模型（2HDM）正常情景下的强一阶电弱相变（SFOEWPTs）及其相关的随机引力波（GW）背景进行了全面的全局分析，其中较轻的\(CP\)偶数标量被识别为观测到的\(125GeV\)希格斯玻色子。在所有四种汤川结构（I型、II型、X型和Y型）中，我们追踪了有限温度下的真空演化、相变动力学和引力波特征。为了量化与热重整化相关的理论不确定性，我们对Parwani和Arnold - Espinosa方法进行了详细比较。虽然两种方法都发现单步路径在成功相变中占主导地位且始终有利于希格斯对齐极限，但由此产生的SFOEWPT参数空间表现出明显的方法依赖性。Arnold - Espinosa方法严重限制了可行参数空间（重标量质量上限约低于800GeV），并引入了极端的参数敏感性，在重标量质量平面上产生碎片化分布和不规则空洞。相比之下，更稳定的Parwani方法允许重标量质量低于约\(1.6TeV\)。我们进一步确定了能够产生四年LISA信噪比高于10的高度受限的引力波参数区域，同时表明声学引力波源通常寿命较短，导致预测信号幅度大幅抑制。我们的结果突出了未来基于空间的引力波观测与高能对撞机搜索在探测2HDM宇宙学可行性方面的强互补性。
英文摘要
We present a comprehensive global analysis of strong first-order electroweak phase transitions (SFOEWPTs) and their associated stochastic gravitational-wave (GW) backgrounds within the Normal Scenario of the $CP$-conserving Two-Higgs-Doublet Model (2HDM) with softly broken $Z_2$ symmetry, where the lighter $CP$-even scalar is identified as the observed $125~\text{GeV}$ Higgs boson. Across all four Yukawa structures (Type-I, II, X, and Y), we track the finite-temperature vacuum evolution, transition dynamics, and GW signatures. To quantify the theoretical uncertainty associated with thermal resummation, we perform a detailed comparison between the Parwani and Arnold--Espinosa prescriptions. While both schemes find that single-step paths overwhelmingly dominate successful transitions and consistently favor the Higgs alignment limit, the resulting SFOEWPT parameter space exhibits a pronounced scheme dependence. The Arnold-Espinosa prescription severely restricts the viable parameter space (with upper bounds on the heavy-scalar masses below approximately 800 GeV) and introduces an extreme parametric sensitivity that produces fragmented distributions and irregular voids in the heavy-scalar mass planes. In contrast, the more stable Parwani prescription allows heavy-scalar masses below $\sim 1.6~\text{TeV}$. We further identify highly restricted GW parameter regions capable of yielding a four-year LISA signal-to-noise ratio above 10, while demonstrating that the acoustic GW source is generically short-lived, leading to a substantial suppression of the predicted signal amplitude. Our results highlight the strong complementarity between future space-based GW observations and high-energy collider searches in probing the cosmological viability of the 2HDM.
Comments49 pages with 16 figures
