The static electromagnetic properties of the $W$ boson, $Δκ$ and $ΔQ$, are calculated in the T-parity and non T-parity littlest Higgs model (LHM) including terms up to the order of $(v/f)^4$, with $v$ the standard model (SM) vacuum expectation value and $f$ the scale of the global symmetry breaking. There are contributions from the virtual effects of the new heavy particles and also from the new corrections to the SM vertices, which depend on the mixing parameter $c$ and decrease quickly as $f$ increases. Depending on the value of $c$, the partial contributions to $Δκ$ and $ΔQ$ can add constructively or destructively. The terms of the order of $(v/f)^4$ are subdominant but they can add constructively and can enhance the $W$ form factors for $f < 1$ TeV. In general the size of the $W$ form factors is very suppressed in the LHM without T-parity as the constraints on the scale $f$ from electroweak precision measurements are very tight. The LHM with T-parity has no such constraints and it allows for values of $W$ form factors similar to those found in other weakly coupled SM extensions, though they are out of the expected sensitivity of future measurements at the LHC. We also discuss the possibility that there is some enhancement due to the interactions arising from the strongly interacting ultraviolet completion of the LHM.
Associated production of single top and Higgs at the LHC in the littlest Higgs model with T-parity
在具有T宇称的最小Higgs模型(LHT)中,我们研究了在8和14 TeV LHC上与希格斯玻色子相关的$t$通道单顶产生.我们发现,与标准模型相比,该模型可以明显地增强横截面。通过在14 TeV LHC上利用$pp\rightarrow t(\rightarrow \ell^{+}νb)h(\rightarrow b\bar{b})j$进行简单的部分子级模拟,我们发现在有利的参数空间中信号的可观测性是有希望的。
In the littlest Higgs model with T-parity, we study associated production of a Higgs and a single top quark at the 14 TeV LHC. We focus on the Higgs to two photons decay and the semileptonic top decay channel. By performing a fast detector simulation, we find that the $thj$ search in the selected channel can excluded the top partner mass $m_{T_{+}}$ up to 805 (857) GeV for case A (case B) at $2σ$ confidence level at 14 TeV LHC with the integrated luminosity $L= 3 \rm ab^{-1}$.
We first study the hadronic lepton flavor violating tau decays within the littlest Higgs model with T-parity (including one or two pseudoscalars, or a vector resonance). We consider the case where only T-odd particles and partner fermions contribute, and also its extension including Majorana neutrinos coming from an inverse seesaw. In both cases our mean values lie only one order of magnitude below current upper limits, strengthening the case of searching for these decays in the quest for new physics.
We show that the inverse see-saw is the most natural way of implementing neutrino masses in the Littlest Higgs model with T-parity. The three extra quasi-Dirac neutrinos are needed to cancel the quadratically divergent contributions of the mirror leptons to the Higgs mass. If the T-parity of the heavy neutrino singlets is chosen to be even, their contributions to lepton flavor violating transitions are one-loop finite. The most stringent limits on this scenario result from the non-observation of these transitions. Constraints on neutrino mixing imply an upper bound on the mass of the T-odd mir…
Inspired by the recent CMS $h \to μτ$ excess, we calculate the lepton flavor violating Higgs decay $h \to μτ$ in the littlest Higgs model with T-parity (LHT). Under the constraints of $\ell_i \to \ell_j γ$, $Z \to \ell_i \bar{\ell}_j$ and Higgs data, we find that the branching ratio of $h \to μτ$ can maximally reach $\mathcal O(10^{-4})$. We also investigate the correlation between $h \to μτ$, $τ\to μγ$ and $Z \to μτ$, which can be used to test LHT model at future $e^+e^-$ colliders.
In the framework of the littlest Higgs Model with T-parity, we discuss the top partner production at future $e^{+}e^{-}$ collider. We calculate the cross sections of the top partner production processes and associated production processes of Higgs and top partner under current constraints. Then, we investigate the observability of the T-odd top partner pair production through the process $e^{+}e^{-}\rightarrow T_{-}\bar{T}_{-}\rightarrow t\bar{t}A_{H}A_{H}$ in the $t\bar{t}$ di-lepton channel for two T-odd top partner mass $m_{T_{-}}$=603(708) GeV at $\sqrt{s}$=1.5 TeV. We analyze the signal s…
Quark and Lepton Flavour Physics in the Littlest Higgs Model with T-Parity
T宇称的最小希格斯模型(LHT)在夸克和轻子扇区都包含了新的味源和CP破坏。它们起源于新规范玻色子W_H、Z_H和A_H介导的普通费米子与镜像费米子的相互作用。在K_L -> pi ^0 nu {bar nu}、K^+ -> pi^+ nu {bar nu}、CP不对称性S_{psi phi}和轻子味违反衰变中,发现了与标准模型最惊人的偏离。特别是,后者的衰变提供了一个明确的区别LHT模型和MSSM。我们总结了最有趣的结果,三个广泛的分析味道物理的LHT模型。
We study lepton flavor violation (LFV) within the Littlest Higgs Model with T parity (LHT) realizing an inverse seesaw (ISS) mechanism of type I. With respect to the traditional LHT, there appear new $\mathcal{O}$(\textcolor{black}{10} TeV) Majorana neutrinos, driving LFV. For $τ\to\ell\ell'\bar{\ell}"$ (including wrong-sign, $\ell=e, μ$) decays and $μ\to e$ conversion in Ti, we get typical rates only one order of magnitude below present bounds ($\ell\to\ell'γ$ can reach the current upper limit) and for $Z\to\barτ\ell$, $μ\to e e \bar{e}$ and conversion in Au, results are within two orders of …