论文标题
LHC的基准在Georgi-Machacek模型中搜索低质量托管五型标量
A benchmark for LHC searches for low-mass custodial fiveplet scalars in the Georgi-Machacek model
论文作者
论文摘要
Georgi-Machacek（GM）模型用于激励和解释LHC搜索对向量玻色子对的双重电荷标量衰减。双重电荷标量是带有状态$ h_5^{\ pm \ pm} $，$ h_5^\ pm $的fermiophopic Custodial Fiveple的一部分，$ H_5^\ pm $，$ H_5^0 $和常见的质量$ M_5 $。通用汽车模型已在LHC上以$ _5> 200美元的GEV进行了广泛的研究，但是在很大程度上没有参数空间的无探针区域，从$ 120 $ gev $ <m_5 <200 $ gev，其中可能存在光线充电的标量。该区域被实验搜索忽略了，部分原因是缺乏$ m_5 <200 $ GEV的基准。在本文中，我们为GM型号提出了一个新的“低$ M_5 $”基准，该基准定义为$ M_5 \ in（50，550）$ GEV，并表征其属性。我们应用了所有现有的实验约束，并总结了幸存参数空间的现象学。我们表明，基准几乎以低于200 GEV的$ m_5 $ $ m_5 $的参数平面覆盖了整个允许的参数平面，并满足了125 GEV Higgs Boson信号强度的约束。我们计算了125 GEV Higgs Boson与费米昂和矢量玻色子对的耦合，并表明它们在基准中始终相对于标准模型中的基准增强。我们还计算了LHC上$ H_5 $的最相关的生产交叉部分，包括$ H_5 $ Pairs的Drell-Yan生产。该过程$ pp \ to H \至H_5 H_5 $在参数空间的较小区域中做出了贡献，但与Drell-Yan生产横截面相比很小。最后，我们计算$ H_5^0 \至γγ$和$ H_5^{\ pm} \ w^{\ pm}γ$的分支比率。 $ h_5 $状态中每个状态的宽度比率低于整个基准的1 \％，因此狭窄的宽度近似值是合理的。
The Georgi-Machacek (GM) model is used to motivate and interpret LHC searches for doubly charged scalars decaying to vector bosons pairs. The doubly charged scalars are part of a degenerate fermiophobic custodial fiveplet with states $H_5^{\pm\pm}$, $H_5^\pm$, and $H_5^0$ and common mass $m_5$. The GM model has been extensively studied at the LHC for $m_5 > 200$ GeV but there is a largely unprobed region of parameter space from $120$ GeV $< m_5 < 200$ GeV where light doubly-charged scalars could exist. This region has been neglected by experimental searches due in part to the lack of a benchmark for $m_5 < 200$ GeV. In this paper we propose a new "low-$m_5$" benchmark for the GM model, defined for $m_5 \in (50, 550)$ GeV, and characterize its properties. We apply all existing experimental constraints and summarize the phenomenology of the surviving parameter space. We show that the benchmark populates almost the entirety of the relevant allowed parameter plane for $m_5$ below 200 GeV and satisfies the constraints from the 125 GeV Higgs boson signal strengths. We compute the 125 GeV Higgs boson's couplings to fermion and vector boson pairs and show that they are always enhanced in the benchmark relative to those in the Standard Model. We also compute the most relevant production cross sections for $H_5$ at the LHC, including Drell-Yan production of $H_5$ pairs. The process $pp \to H \to H_5 H_5$ contributes in a small region of parameter space, but is small compared to the Drell-Yan production cross section. Finally we compute the branching ratios of $H_5^0 \to γγ$ and $H_5^{\pm} \to W^{\pm} γ$. The width-to-mass ratio of each of the $H_5$ states is below 1\% over the entire benchmark, so that the narrow-width approximation is well justified.
