AI 中文总结
本研究探讨2HDM中电弱相变的对撞机与GW探测协同效应，发现LISA可及GW信号对应HL-LHC可观测区域，部分需参数微调的情况需结合多工具评估理论不确定性。
AI 中文摘要
标准模型标量场的扩展可使电弱相变成为一阶相变，从而为电弱重子生成提供所需的热平衡偏离，同时产生毫赫兹范围内的随机引力波（GW）背景。本研究探讨CP守恒的I型双希格斯二重态模型（2HDM）中的电弱相变，重点关注高亮度大型强子对撞机（HL-LHC）的对撞机约束与LISA预计灵敏度之间的相互作用。我们计算强一阶电弱相变产生的预期GW背景，并在对撞机可行的模型参数空间上进行广泛的蒙特卡罗扫描。结果发现，LISA可探测到的GW信号几乎仅出现在必然会在HL-LHC产生可观测偏差的参数空间区域，尤其是通过重CP-even中性希格斯态的H→ZZ衰变道，其质量m_H约为180–250 GeV。我们的结果凸显了对撞机与GW探测之间的决定性互补性，表明LISA相变信号相关的2HDM参数空间大部分已可被HL-LHC探测。然而，HL-LHC未来可能发现2HDM态，却无法对LISA能否探测到GW背景做出确定性结论，因为可观测GW信号需要大量参数微调。为评估该结论的潜在警告，我们采用两种方法研究GW预测相关的理论不确定性，使用最先进的工具BSMPT和TransitionListener，并考虑电弱对称性在高温极限下不恢复的模型实现，这类模型结合了最强的GW信号和最弱的对撞机覆盖。
英文摘要
Extensions of the Standard Model scalar sector can render the electroweak phase transition first-order and thereby provide the departure from thermal equilibrium required for electroweak baryogenesis, while at the same time sourcing a stochastic gravitational wave (GW) background in the milli-Hertz range. In this work, we investigate electroweak phase transitions in the CP-conserving type-I two-Higgs-doublet model (2HDM), focusing on the interplay between collider constraints at the HL-LHC and the projected sensitivity of LISA. We compute the expected GW background due to strong first-order electroweak phase transitions and perform extensive Monte Carlo scans over the collider-viable model parameter space. We find that GW signals within reach of LISA arise almost exclusively in regions of parameter space that necessarily predict observable deviations at the HL-LHC, in particular through the $H \to ZZ$ decay channel of the heavy CP-even and neutral Higgs state with $m_H \simeq 180\text{--}250 \, \text{GeV}$. Our results highlight the decisive complementarity between collider and GW probes and show that the largest parts of the 2HDM parameter space relevant for phase transition signals at LISA can already be tested by HL-LHC. A possible future discovery of 2HDM states at the HL-LHC, however, would not allow conclusive statements about LISA being able to find a GW background due to the amount of parameter tuning required for an observable GW signal. In order to evaluate possible caveats of this statement we study the theoretical uncertainties related to the GW predictions in a two-fold approach using both state-of-the-art tools, BSMPT and TransitionListener, and also allow for model realizations in which the electroweak symmetry is not restored in the high-temperature limit, which are the ones combining the loudest GW signals with the weakest collider coverage.
Comments52 pages, 12 figures
