Type-I 2HDM 中强一阶电弱相变的截断能标：一步与多步
Cutoff Scales in the Type-I 2HDM with Strongly First-Order Electroweak Phase Transitions: One-Step versus Multistep
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中文总结 AI 辅助
本文研究 Type-I 2HDM 中强一阶电弱相变的紫外可行性，发现一步相变中强度与截断能标存在张力，而两步相变（主要在 IS 中）可同时达到高截断能标和强相变，并锐化了对撞机搜索参数空间。
中文摘要 AI 辅助
我们研究了 Type-I 双希格斯二重态模型（2HDM）中强一阶电弱相变（SFOEWPT）的紫外（UV）可行性，同时考虑了正常（NS）和倒置（IS）两种情形。对于每种情形，我们扫描了 $5\times10^6$ 个物理参数点，并通过双圈重整化群分析确定了截断能标 $\Lambda_{\rm c}$，其中 $\Lambda_{\rm c}$ 由微扰性、树级幺正性或真空稳定性的首次违反所设定。对于一步相变，SFOEWPT 强度与高能标 UV 有效性之间存在显著张力：最大相变强度 $\xi_p$ 随 $\Lambda_{\rm c}$ 增大而减小。要求 $\Lambda_{\rm c}>10~\text{TeV}$ 将相变强度限制为 NS 中 $\xi_p\lesssim2.7$，IS 中 $\xi_p\lesssim1.8$；而要求 $\xi_p>1$ 则将截断能标限制为两种情形下 $\Lambda_{\rm c}\lesssim O(10^6)~\text{GeV}$。多步相变表现出定性不同的行为。仅在 IS 中以可观数量发现的两步 SFOEWPT，可以在 $\Lambda_{\rm c}\sim O(10^{15})~\text{GeV}$ 下保持理论一致性，同时达到 $\xi_p\simeq7$，且不表现出一步相变特有的 $\xi_p$-$\Lambda_{\rm c}$ 反相关。施加 UV 有效性还锐化了现象学上可行的参数空间。特别是，提高 IS 中两步 SFOEWPT 的最小允许截断能标，有利于轻标量谱和中等 $\tan\beta$，为当前和未来的对撞机搜索提供了有前景的目标。
英文摘要
We investigate the UV viability of strongly first-order electroweak phase transitions (SFOEWPTs) in the Type-I two-Higgs-doublet model (2HDM), considering both the Normal and Inverted Scenarios (NS and IS). For each scenario, we scan $5\times10^6$ physical parameter points and determine the cutoff scale $Λ_{\rm c}$ through a two-loop renormalization-group analysis, where $Λ_{\rm c}$ is set by the first violation of perturbativity, tree-level unitarity, or vacuum stability. For one-step transitions, the SFOEWPT strength and high-scale UV validity exhibit a pronounced tension: the maximal transition strength $ξ_p$ decreases with increasing $Λ_{\rm c}$. Requiring $Λ_{\rm c}>10~\text{TeV}$ limits the transition strength to $ξ_p\lesssim2.7$ in the NS and $ξ_p\lesssim1.8$ in the IS, while requiring $ξ_p>1$ restricts the cutoff scale to $Λ_{\rm c}\lesssim O(10^6)~\text{GeV}$ in both scenarios. Multistep transitions exhibit qualitatively different behavior. Two-step SFOEWPTs, found in appreciable numbers only in the IS, can remain theoretically consistent up to $Λ_{\rm c}\sim O(10^{15})~\text{GeV}$ while reaching $ξ_p\simeq7$, without exhibiting the pronounced $ξ_p$-$Λ_{\rm c}$ anticorrelation characteristic of one-step transitions. Imposing UV validity also sharpens the phenomenologically viable parameter space. In particular, increasing the minimum allowed cutoff scale for two-step SFOEWPTs in the IS favors a light scalar spectrum and moderate $\tanβ$, providing a promising target for current and future collider searches.
发表机构
- National Institute for Mathematical Sciences（韩国数学科学研究院）
- Department of Physics, Konkuk University（建国大学物理系）
- School of Physics, Korea Institute for Advanced Study（韩国高等研究院物理学院）
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