AI 中文总结
该研究分析了共形与非共形N2HDM的宇宙学特征，确定了可产生未来空间干涉仪可测随机引力波的参数区域，发现二者标量质量谱分布不同，还研究了希格斯对产生的相关特性。
AI 中文摘要
我们研究次最小双希格斯二重态模型（N2HDM）在经典标度不变（即共形）实现形式及对应非共形理论中的宇宙学特征。借助单圈有限温度有效势、通过ScannerS、HiggsBounds和HiggsSignals实现的对撞机与味约束，以及针对共形模型的修正在壳抵消项方案，我们确定了具有一阶电弱相变且可能观测到随机引力波的参数区域。我们发现，共形与非共形场景均可产生处于未来空间干涉仪（包括LISA）灵敏度范围内的声波信号，且电弱相变完成迅速（Tn≈Tp），仅在最强相变的临界温度以下存在明显过冷。然而，当引力波信号可观测时，两种场景会分布在标量质量谱的不同区域，这表明未来随机背景测量结合额外希格斯态的对撞机信息可区分两种实现形式。我们还在重顶近似下研究了部分子希格斯对产生，发现类标准模型（SM）的双希格斯率的大偏差往往出现在最强引力波信号区域之外，而超出标准模型（BSM）的希格斯对率增强主要与共形模型相关。该分析凸显了扩展希格斯领域中电弱宇宙学、标量光谱学与希格斯自相互作用探针之间的互补相互作用。
英文摘要
We investigate cosmological signatures of the next-to-minimal two-Higgs-doublet model (N2HDM) in both the classically scale-invariant, or conformal, realization and in the corresponding non-conformal theory. Using a one-loop finite-temperature effective potential, collider and flavour constraints implemented through ScannerS, HiggsBounds and HiggsSignals, and a modified on-shell counterterm prescription for the conformal model, we identify parameter regions with a first-order electroweak phase transition and potentially observable stochastic gravitational waves. We find that both conformal and non-conformal scenarios can produce sound-wave signals in the sensitivity range of future space-based interferometers, including LISA, while the electroweak transitions complete promptly ($T_n\simeq T_p$), with pronounced supercooling below the critical temperature confined to the strongest transitions. The two scenarios nevertheless populate different regions of the scalar mass spectrum when the gravitational-wave signal is observable, suggesting that a future stochastic background measurement combined with collider information on the additional Higgs states could discriminate between the two realizations. We further study partonic Higgs-pair production, in the heavy-top approximation, and find that large deviations in the SM-like di-Higgs rate tend to occur away from the regions with the strongest gravitational-wave signals, while enhanced BSM Higgs-pair rates are mainly associated with the conformal model. The analysis highlights a complementary interplay between electroweak cosmology, scalar spectroscopy and Higgs self-interaction probes in extended Higgs sectors.
