Complete Light Long-Lived Particles searches in Type-I 2HDM
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arXiv
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| _version_ | 1866912540941877248 |
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| author | Qi, Xueying Song, Huayang Su, Wei |
| author_facet | Qi, Xueying Song, Huayang Su, Wei |
| contents | Recently, the study of long-lived particles (LLPs) has attracted increasing attention. In this work, we analyze the full parameter space of the Type-I Two-Higgs-Doublet Model (2HDM) that allows for light long-lived scalar ($H$) and pseudoscalar ($A$) particles. When involving a light beyongd Standard Model (BSM) Higgs, the $ΔS$ could be the main contribution during the global fit of the oblique parameters, which is different to $ΔT$ being the main factor for heavy BSM Higgs cases. By imposing theoretical constraints such as vacuum stability and perturbative unitarity, together with current experimental bounds, we summarize a complete region for a potential light $H$ with $\cos(β- α) \simeq \frac{1}{\tan β}$, light $A$ with $\cos(β- α) \simeq \frac{1}{\tanβ} \frac{2m_H^2 - m_h^2}{m_H^2 - m_h^2}$, and point out the invisible Higgs decay is the most important constraint. We further identify viable regions for LLPs and propose four benchmark regions that simultaneously accommodate a light long-lived particle and explain the $W$ boson mass anomaly. For these benchmarks, we present the reaches of FASER and FASER~2, where FASER~2 improves the sensitivity by approximately two orders of magnitude compared to FASER. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2508_12309 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Complete Light Long-Lived Particles searches in Type-I 2HDM Qi, Xueying Song, Huayang Su, Wei High Energy Physics - Phenomenology Recently, the study of long-lived particles (LLPs) has attracted increasing attention. In this work, we analyze the full parameter space of the Type-I Two-Higgs-Doublet Model (2HDM) that allows for light long-lived scalar ($H$) and pseudoscalar ($A$) particles. When involving a light beyongd Standard Model (BSM) Higgs, the $ΔS$ could be the main contribution during the global fit of the oblique parameters, which is different to $ΔT$ being the main factor for heavy BSM Higgs cases. By imposing theoretical constraints such as vacuum stability and perturbative unitarity, together with current experimental bounds, we summarize a complete region for a potential light $H$ with $\cos(β- α) \simeq \frac{1}{\tan β}$, light $A$ with $\cos(β- α) \simeq \frac{1}{\tanβ} \frac{2m_H^2 - m_h^2}{m_H^2 - m_h^2}$, and point out the invisible Higgs decay is the most important constraint. We further identify viable regions for LLPs and propose four benchmark regions that simultaneously accommodate a light long-lived particle and explain the $W$ boson mass anomaly. For these benchmarks, we present the reaches of FASER and FASER~2, where FASER~2 improves the sensitivity by approximately two orders of magnitude compared to FASER. |
| title | Complete Light Long-Lived Particles searches in Type-I 2HDM |
| topic | High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2508.12309 |