分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： In the minimal supersymmetric standard model (MSSM) extended by a singlet superfield, when the coupling between the singlet sector and the MSSM sector is tiny, the singlet sector can be a quasi dark sector with supersymmetry (SUSY). We investigate the cosmological phenomena in this scenario and obtain the following observations: (i) In the parameter space solving the small cosmological scale anomalies via self-interacting singlino dark matter (SIDM), a first-order phase transition (FOPT) can readily happen but requires rather light dark matter below MeV; (ii) The corresponding parameter space indicated by FOPT and SIDM can be partially covered by detecting the phase-transition gravitational waves (GWs) at the near-future projects, such as LISA, TianQin and Taiji. Therefore, the recently developed GW astronomy could be a novel probe to such a SUSY scenario.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We study the dilution of dark matter (DM) relic density caused by the electroweak first-order phase transition (FOPT) in the singlet extension models, including the singlet extension of the standard model (xSM), of the two-Higgs-doublet model (2HDM+S) and the next-to-minimal supersymmetric standard model (NMSSM). We find that in these models the entropy released by the strong electroweak FOPT can dilute the DM density to 1/3 at most. Nevertheless, in the xSM and NMSSM where the singlet field configure is relevant to the phase transition temperature, the strong FOPT always happens before the DM freeze-out, making the dilution effect negligible for the current DM density. On the other hand, in the 2HDM+S where the DM freeze-out temperature is independent of FOPT, the dilution may salvage some parameter space excluded by excessive DM relic density or by DM direct detections.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： The vacuum stability problem is usually studied assuming that the universe is located in the desired electroweak-breaking vacuum. This may not be the case, however, as seen by checking the evolution history of the early universe. The transition to the stable desired vacuum may not be possible, or the desired vacuum could be meta-stable and long-lived but the universe may already be in an undesired global vacuum from an early stage. We reveal that these situations exist even in the simplest singlet extension of the Standard Model, propose a general procedure to identify them, and divide the parameter space according to different cases. We find that checking cosmological history can provide a more stringent, reasonable and sometimes computationally cheaper limit of vacuum stability on new physics models than the traditional
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We study the dilution of dark matter (DM) relic density caused by the electroweak first-order phase transition (FOPT) in the singlet extension models, including the singlet extension of the standard model (xSM), of the two-Higgs-doublet model (2HDM+S) and the next-to-minimal supersymmetric standard model (NMSSM). We find that in these models the entropy released by the strong electroweak FOPT can dilute the DM density to 1/3 at most. Nevertheless, in the xSM and NMSSM where the singlet field configure is relevant to the phase transition temperature, the strong FOPT always happens before the DM freeze-out, making the dilution effect negligible for the current DM density. On the other hand, in the 2HDM+S where the DM freeze-out temperature is independent of FOPT, the dilution may salvage some parameter space excluded by excessive DM relic density or by DM direct detections.
分类： 物理学 >> 基本粒子与场物理学 提交时间： 2017-08-03
摘要： : We perform a detailed semi-analytical analysis of the electroweak phase transition (EWPT) property in NMSSM, which serves as a good benchmark model in which the 126 GeV Higgs mixes with a singlet. In this case, a strongly first order electroweak phase transition (SFOEWPT) is achieved by the tree-level effects and the phase transition strength γc is determined by the vacua energy gap at T = 0. We make an anatomy of the energy gap at both tree-level and loop-level and extract out a dimensionless phase transition parameter Rκ ≡ 4κvs/Aκ, which can replace Aκ in the parameterization and affect the light CP odd and even Higgs spectra. We find that SFOEWPT only occurs in Rκ ∼ −1 and positive Rκ . O(10), which in the non-PQ limit case would prefer either a relatively light CP odd or CP even Higgs boson ∼ (60, 100) GeV, therefore serves as a smoking gun signal and requires new search strategies at the LHC.
点击量
待评议
点击量
下载量
评论
