We study phenomenological consequences of the Standard Model extension by the new spin-1 fields with the internal quantum numbers of the electroweak Higgs doublets. We show, that there are at least three different classes of theories, all motivated by the hierarchy problem, which predict appearance of such vector weak-doublets not far from the weak scale. The common feature for all the models is the existence of an SU(3) gauge extension of the weak SU(2) group, which is broken down to the latter at some energy scale around TeV. The Higgs doublet then emerges as either a pseudo-Nambu-Goldstone boson of a global remnant of SU(3), or as a symmetry partner of the true eaten-up Goldstone boson. In the third class, the Higgs is a scalar component of a high-dimensional SU(3) gauge field. The common phenomenological feature of these theories is the existence of the electroweak doublet vectors (Z*,W*), which in contrast to well-known Z' and W' bosons posses only anomalous (magnetic moment type) couplings with ordinary light fermions. This fact leads to some unique signatures for their detection at the hadron colliders.
We introduce a new way of modeling the physics beyond the Standard Model by considering fake, strictly off-shell degrees of freedom: the fakeons. To demonstrate the approach and exemplify its reach, we re-analyze the phenomenology of the Inert Doublet Model under the assumption that the second doublet is a fakeon. Remarkably, the fake doublet avoids the most stringent $Z$-pole constraints regardless of the chosen mass scale, thereby allowing for the presence of new effects well below the electroweak scale. Furthermore, the absence of on-shell propagation prevents fakeons from inducing missing …
We study the inclusion of new heavy fermions on complex scalar dark matter (DM) phenomenology within gauged two Higgs doublet model (G2HDM). We find that for DM mass above 1 TeV, heavy quarks coannihilations into the Standard Model (SM) quarks and gluons dominate the thermally-averaged cross section relevant for the relic abundance of complex scalar DM. We demonstrate that the effects of QCD Sommerfeld correction as well as QCD bound state formation in determining the DM relic are negligible. We show that the allowed parameter space is significantly constrained by the current PLANCK relic dens…
We study the dark matter phenomenology of scotogenic frameworks through a rather illustrative model extending the Standard Model by scalar and fermionic singlets and doublets. Such a setup is phenomenologically attractive since it provides the radiative generation of neutrino masses, while also including viable candidates for cold dark matter. We employ a Markov Chain Monte Carlo algorithm to explore the associated parameter space in view of numerous constraints stemming from the Higgs mass, the neutrino sector, dark matter, and lepton-flavour violating processes. After a general discussion of…
Type-X two Higgs doublet model is known to explain the muon $g-2$ anomaly with a relatively light charged Higgs boson at large $\tanβ$. The light charged Higgs boson has been searched in the main $τν$ mode at the colliders. Invoking a scenario of inverse seesaw as the origin of neutrino masses and mixing, the charged Higgs boson can decay additionally to right-handed neutrinos which leads to interesting phenomenology. Considering generic lepton flavour violating signatures at the final states, a $5σ$ discovery can be achieved with the early data of LHC, at 14 TeV, for relatively large inverse …
Yukawa txtures and charged Higgs boson phenomenology in the type-III two-Higgs-doublet model
我们讨论了假设一个四零汤川纹理的带电希格斯玻色子玻色子的性质的一般2-希格斯双重模型的第三类的背景下的影响。我们首先详细分析带电的希格斯玻色子玻色子与重夸克的耦合及其衰变模式。生产的带电希格斯玻色子也是敏感的修改其耦合，使我们也评估所产生的影响，顶部衰变$t \to b H^{+}$以及“直接”$c\bar{b}\to H^++c. c.$和“间接”$q\bar q,gg\to \bar t b H^++c. c.$生产。在大型强子对撞机上存在着几个$H^\pm$产生和衰变通道，使人们能够区分这样一个模型和替代的2-希格斯双态场景。
We present a systematic study of an extension of the Standard Model (SM) with two Higgs doublets and one complex singlet (2HDM+S). In order to gain analytical understanding of the parameter space, we re-parameterize the 27 parameters in the Lagrangian by quantities more closely related to physical observables: physical masses, mixing angles, trilinear and quadratic couplings, and vacuum expectation values. Embedding the 125\,GeV SM-like Higgs boson observed at the LHC places stringent constraints on the parameter space. In particular, the mixing of the SM-like interaction state with the remain…
We consider the doublet-triplet fermionic model in the scheme of the custodial limit when the dark matter (DM) candidate is pure doublet and lies at the electroweak scale. This scheme, despite being an appealing and promising DM model, is severely constrained by the interplay between the DM relic density constraint and the LHC measurement of the Higgs diphoton decay rate. In this work, the DM relic density is considered to arise from either a nonstandard cosmology scenario or as a part of a larger sector encompassing other DM particles, this in order to saturate the observed relic abundance. F…
We study the most popular scalar extension of the Standard Model, namely the Two Higgs doublet model, extended by a complex triplet scalar (2HDMcT). Such considering model with a very small vacuum expectation value, provides a solution to the massive neutrinos through the so-called type II seesaw mechanism. We show that the 2HDMcT enlarged parameter space allow for a rich and interesting phenomenology compatible with current experimental constraints. In this paper the 2HDMcT is subject to a detailed scrutiny. Indeed, a complete set of tree level unitarity constraints on the coupling parameters…
我们分析了一个模型的希格斯部门与两个标量双峰和一个$Z_2$对称性，这是明显的汤川部门，但打破了潜在的。因此，其中一个二重态破坏了电弱对称性，与费米子有三能级汤川耦合，而另一个二重态没有真空期望值，也没有与费米子的三能级耦合。由于$Z_2$宇称被打破，两个双峰可以混合，这导致了一个独特的和新颖的现象。该隐形双态模型可以看作是具有破缺的$Z_2$对称性的惰性双态模型的推广。我们概述了模型和理论，电弱精密测试和对撞机搜索，包括最近观察到的希格斯玻色子在大型强子对撞机目前的限制。带电标量$H^\pm$和CP奇标量$A$在单圈能级上与费米子耦合。我们计算了$H^\pm$和$A$的衰变，特别是单圈衰变$A \to f \bar{f}$、$H^\pm \to f \bar{f}^\prime $、$H^\pm \to W^\pm Z $和$H^\pm \to W^\pm γ$。我们还描述了如何计算和重正化我们的模型中这样的过程。我们发现，如果$H^\pm$或$A$中的一个是最轻的标量，则$H^\pm \to W^\pm γ$或$ A \to b \bar{b} $通常是它们各自的主导衰变通道。另外，$H^\pm$和$A$的主导衰变为标量和矢量。由于$H^\pm$和$A$不存在树能级的费米子耦合，我们考虑了在大型强子对撞机上的电子对产生以及与矢量玻色子和标量相关的产生。如果支持$H^\pm \t…
The inert doublet model is a minimal dark matter model with strong theoretical motivations, where the stability of dark matter is usually achieved by imposing a $Z_2$ parity. We promote the $Z_2$ parity into a global $U(1)$ symmetry and study its phenomenological implications. There are two characteristic features of the model: both the CP-even and CP-odd neutral inert scalars, $h_1$ and $h_2$, become DM candidates; the number of model parameters is one less than that with $Z_2$ parity. We first analyze the constraints from LEP experiments, electroweak precision tests, theoretical stability, H…
In this thesis, we investigate several aspects of models with a multiplicity of Higgs bosons. We start by focusing on models with two Higgs doublets. We claim that one of the most used models in the literature -- the so-called real 2-Higgs-Doublet Model (2HDM) -- is inconsistent. We give special emphasis to the model that corrects it in the most simple way, the complex 2HDM; we study its phenomenology in the lowest order of perturbation theory and describe its renormalization in the following order. Motivated by this renormalization, we analyze in detail tadpole schemes that allow the selectio…
Motivated by the recently reported anomaly in W boson mass by the CDF collaboration with $7σ$ statistical significance, we consider a singlet-doublet (SD) Majorana fermion dark matter (DM) model where the required correction to W boson mass arises from radiative corrections induced by SD fermions. While a single generation of SD fermions, odd under an unbroken $Z_2$ symmetry, can not explain the W boson mass anomaly while being consistent with DM phenomenology, two generations of SD fermions can do so with the heavier generation playing the dominant role in W-mass correction and lighter genera…
