Ellis John, Evans Jason L, Luo Feng, Olive Keith A, Zheng Jiaming
1Theoretical Particle Physics and Cosmology Group, Department of Physics, King's College London, Strand, London, WC2R 2LS UK.
2National Institute of Chemical Physics and Biophysics, Rävala 10, 10143 Tallinn, Estonia.
Eur Phys J C Part Fields. 2018;78(5):425. doi: 10.1140/epjc/s10052-018-5831-z. Epub 2018 May 28.
Stop coannihilation may bring the relic density of heavy supersymmetric dark matter particles into the range allowed by cosmology. The efficiency of this process is enhanced by stop-antistop annihilations into the longitudinal (Goldstone) modes of the and bosons, as well as by Sommerfeld enhancement of stop annihilations and the effects of bound states. Since the couplings of the stops to the Goldstone modes are proportional to the trilinear soft supersymmetry-breaking -terms, these annihilations are enhanced when the -terms are large. However, the Higgs mass may be reduced below the measured value if the -terms are too large. Unfortunately, the interpretation of this constraint on the stop coannihilation strip is clouded by differences between the available Higgs mass calculators. For our study, we use as our default calculator FeynHiggs 2.13.0, the most recent publicly available version of this code. Exploring the CMSSM parameter space, we find that along the stop coannihilation strip the masses of the stops are severely split by the large -terms. This suppresses the Higgs mass drastically for and , whilst the extent of the stop coannihilation strip is limited for and either sign of . However, in sub-GUT models, reduced renormalization-group running mitigates the effect of the large -terms, allowing larger LSP masses to be consistent with the Higgs mass calculation. We give examples where the dark matter particle mass may reach TeV.
停止共湮灭可能会使重超对称暗物质粒子的遗迹密度进入宇宙学允许的范围。这个过程的效率通过停止-反停止对W和Z玻色子纵向（戈德斯通）模式的湮灭、停止湮灭的索末菲增强以及束缚态的影响而得到增强。由于停止与戈德斯通模式的耦合与三线性软超对称破缺A项成正比，当A项很大时，这些湮灭会增强。然而，如果A项太大，希格斯玻色子质量可能会降低到测量值以下。不幸的是，可用的希格斯玻色子质量计算器之间的差异使对停止共湮灭带的这一限制的解释变得模糊。在我们的研究中，我们使用FeynHiggs 2.13.0作为默认计算器，这是该代码的最新公开版本。探索CMSSM参数空间时，我们发现在停止共湮灭带上，停止的质量由于大的A项而严重分裂。这对于较大的tanβ和较大的|μ|会极大地压低希格斯玻色子质量，而对于较小的tanβ和μ的任何符号，停止共湮灭带的范围都会受到限制。然而，在亚大统一理论模型中，重整化群跑动的降低减轻了大A项的影响，使得更大的最轻超对称粒子质量与希格斯玻色子质量计算结果一致。我们给出了暗物质粒子质量可能达到1 TeV的例子。
