The Georgi-Machacek model is used to motivate and interpret LHC searches for doubly- and singly-charged Higgs bosons decaying into vector boson pairs. In this paper we study the constraints on and phenomenology of the "H5plane" benchmark scenario in the Georgi-Machacek model, which has been proposed for use in these searches. We show that the entire H5plane benchmark is compatible with the LHC measurements of the 125 GeV Higgs boson couplings. We also point out that, over much of the H5plane benchmark, the lineshapes of the two CP-even neutral heavy Higgs bosons $H$ and $H_5^0$ will overlap and interfere when produced in vector boson fusion with decays to $W^+W^-$ or $ZZ$. Finally we compute the decay branching ratios of the additional heavy Higgs bosons within the H5plane benchmark to facilitate the development of search strategies for these additional particles.
We discuss the vacuum structure of a version of the Georgi-Machecek model with an exact $\mathbb{Z}_2$ symmetry acting on the triplet fields. Besides the usual custodial-symmetric model, with $ρ=1$ at tree-level, a model with a dark matter candidate is also viable. The other phases of the model lead to electric charge breaking, a wrong pattern of electroweak symmetry breaking or to $ρ\neq 1$ at tree-level. We derive conditions to have an absolute minimum in each of the two viable phases, the custodial and the dark matter phases.
The recent CDF-II measurement of the mass of the $W$ boson shows a significant tension with the Standard Model (SM) expectation, even when averaged with earlier measurements. The tension can be explained in the framework of any beyond-SM dynamics that contributes substantially to the oblique $S$ and $T$ parameters. As a typical example of such beyond-SM physics, we try to explain the tension in the framework of the Georgi-Machacek model that keeps $ρ=1$ at the tree-level, and explore the parameter space that can accommodate the $W$ mass shift. We find that a sizeable split between the custodia…
We explore the phenomenology of the Georgi-Machacek model extended with two Higgs doublets and vector fermion doublets invariant under $SU(2)_L \times U(1)_Y\times \mathcal {Z}_4 \times \mathcal {Z}_2$. The $\mathcal {Z}_4$ symmetry is broken spontaneously while the imposed $\mathcal {Z}_2$ symmetry forbids triplet fields to generate any vacuum expectation value and leading to an inert dark sector providing a viable candidate for dark matter and generate neutrino mass radiatively. Another interesting feature of the model is leptogenesis arising from decay of vector-like fermions. A detailed st…
Electroweak phase transition and Higgs phenomenology in the Georgi-Machacek model
本文采用Georgi-Machacek模型研究了电弱相变。我们研究了一步和两步强一级电弱相变。SFOEWPT可行的参数空间可以通过未来的14 TeV LHC，HL-LHC和ILC进行测试。LHC Higgs信号强度测量严格限制了SFOEWPT的有效参数空间，在$α\sim 0$附近的一个很小的同位旋二重态和同位旋三重态标量的中性场混合角区域可以允许两步SFOEWPT的发生。三重态真空期望值（VEV）对SFOEWPT和相关的Higgs现象学都至关重要。两步SFOEWPT可以通过三重Higgs耦合搜索和对撞机上的低质量双电荷Higgs搜索与一步SFOEWPT区分开来。
Higgs boson pair productions in the Georgi-Machacek model at the LHC
希格斯玻色子对的产生以其探测希格斯玻色子自耦合的符号和大小的灵敏度而闻名，提供了一种确定是否存在扩展希格斯扇区的方法。Georgi-Machacek（GM）模型扩展了标准模型（SM），引入了具有一个实分量和一个复分量的$SU(2)_L$三重标量场。希格斯粒子的自耦合现在比SM中的范围更广，甚至有可能发生符号翻转。新的重单线态希格斯玻色子玻色子$H^{0}_{1}$可以促进$hh$对的s-通道产生。在这项工作中，我们研究了非共振/共振希格斯玻色子对生产$p p \rightarrow hh$和$p p \rightarrow H^{0}_{1} \rightarrow hh$，专注于$H^0_1$的贡献。我们展示了在13 TeV LHC上用$3.2,\ 30$和$100$ ~fb $^{-1}$的亮度搜索希格斯玻色子玻色子对产生的灵敏度。
In an SU(2) gauge theory, if the gauge bosons turn out to be degenerate after spontaneous symmetry breaking, obviously these mass terms are invariant under a global SU(2) symmetry that is unbroken. The pure gauge terms are also invariant under this symmetry. This symmetry is called the {\em custodial symmetry} (CS). In $\rm SU(2)\times U(1)$ gauge theories, CS implies a mass relation between the $W$ and the $Z$ bosons. The Standard Model (SM), as well as various extensions of it in the scalar sector, possess such a symmetry. In this paper, we critically examine the notion of CS and show that t…
We study the effects of custodial symmetry violation in the Georgi-Machacek (GM) model. The GM model adds isospin-triplet scalars to the Standard Model in a way that preserves custodial symmetry at tree level; however, this custodial symmetry has long been known to be violated at the one-loop level by hypercharge interactions. We consider the custodial-symmetric GM model to arise at some high scale as a result of an unspecified ultraviolet completion, and quantify the custodial symmetry violation induced as the model is run down to the weak scale. The measured value of the eletroweak rho param…
Interpreting the 95 GeV di-photon and di-tau Excesses in the Georgi-Machacek Model
Institute of Physics, Henan Academy of Sciences（河南科学院物理研究所）；Centre for Theoretical Physics, Henan Normal University（河南师范大学理论物理中心）；Center for High Energy Physics, Henan Academy of Sciences（河南科学院高能物理中心）；ARC Centre of Excellence for Dark Matter Particle Physics & CSSM, Department of Physics, Adelaide University（阿德莱德大学物理系暗物质粒子物理学卓越研究中心及CSSM）
The Georgi-Machacek model, introducing a complex and a real scalar triplet as additional components of the electroweak symmetry breaking sector, enables substantial triplet contributions to the weak gauge boson masses, subject to the equality of the complex and the real triplet vacuum expectation values (vev) via a custodial SU(2) symmetry. We present an updated set of constraints on this scenario, from collider data (including those from 137/139~fb$^{-1}$ of luminosity at the Large Hadron Collider), available data on the 125-GeV scalar, indirect limits and also theoretical restrictions from v…
Many researches from both the theoretical and experimental sides have been performed to search for a new Higgs Boson lighter than the 125 $GeV$ Higgs boson which was discovered at the LHC in 2012. In this paper we explore the possibility of constraining a lighter neutral custodial fiveplet scalar $H_{5}^{0}$ in the Georgi-Machacek (GM) model by the latest results of the search for a lighter Higgs boson decaying into two photons from LHC data. The custodial-singlet mass eigenstate $h$ or $H$ is considered to be the LHC observed 125 $GeV$ Higgs boson. A new set of constrained parameters that is …
The $Z_{2}$-symmetric version of the Georgi-Machacek model does not possess a decoupling limit in which all the new particles can be made arbitrarily heavy, opening the possibility that the model can be entirely excluded if experiments reveal no deviations from the Standard Model. We explore this model, focusing on the part of parameter space in which the vacuum expectation value of the triplets, $ν_χ$, is small. In the small-$ν_χ$ limit, the second custodial-singlet scalar field $S$ necessarily becomes very light and can contribute to the total width of the 125 GeV Higgs boson $h$ via $h \to …
Positive definiteness constraints of effective scalar potential in Georgi-Machacek Model
Institute of Physics, Henan Academy of Sciences（中国科学院河南分院物理研究所）；School of Physics, Henan Normal University（河南师范大学物理学院）；School of Physics, Zhengzhou University（郑州大学物理学院）
The CDF II experiment has recently determined the mass of the $W$ boson to be $m_W(\text{CDF II}) = 80.4335 \pm 0.0094~$GeV, which deviates from the standard model prediction at $7σ$ level. Although this new result is in tension with other experiments such as those at LHC and LEP, it is worth discussing possible implications on new physics by this anomaly. We show that this large discrepancy can be explained by non-aligned vacuum expectation values of isospin triplet scalar fields in the Georgi-Machacek model extended with custodial symmetry breaking terms in the potential. The latter is requi…
Global fits and the 95 GeV diphoton excesses in the Supersymmetric Georgi-Machacek Model
Department of Digital Banking, Qilu Bank（齐鲁银行数字银行部）；Zhongtai Securities Institute for Financial Studies, Shandong University（山东大学中泰证券金融研究院）；College of Engineering Physics, Shenzhen Technology University（深圳技术大学工程物理学院）；Department of Physics, Southern Methodist University（南方卫理公会大学物理系）；Centro Andaluz de Fisica de Particulas Elementales (CAFPE), Universidad de Granada (UGR)（格拉纳达大学安达卢西亚基本粒子物理中心）；Department of Physics and Astronomy, Michigan State University（密歇根州立大学物理与天文学系）
Following various LHC indications for new scalars, an interpretation of these is given in terms of the Georgi-Machacek (GM) model. On top of the confirmed SM Higgs boson, there are indications for a light Higgs at 96 GeV, for a CP-odd boson at 400 GeV, A(400), and for a heavy Higgs boson at 660 GeV. An extension of the GM is needed to interpret the fermion couplings of A(400). Potentially interesting deviations are also observed in the ttW cross-section measurement, which naturally fit into this picture. None of them crosses the fatidic five s.d. evidence but the addition of these effects, con…
