The photon-induced processes at the $LHC$ provide clean experimental conditions due to absence of the proton remnants, which might produce complementary and interesting results for tests of the standard model and for searching of new physics. In the context of the littlest $Higgs$ model with T-parity, we consider the photon-induced production of the mirror quarks at the $LHC$. The cross sections for various production channels are calculated and a simply phenomenology analysis is performed by assuming leptonic decays.
One-loop effects on top pair production in the littlest Higgs model with T-parity at the LHC
在这项工作中,我们系统地研究了在LHC上,对于$\sqrt{s}=8,14$ TeV,T宇称的最小Higgs模型(LHT)中$t\bar{t}$产生的单圈修正。重点研究了LHT粒子对LHC中$t\bar{t}$截面、极化不对称性、自旋关联和电荷不对称性的影响。我们还研究了Tevatron上的顶夸克前后不对称性及其与LHC观测值的相关性。我们发现:(1)在14 TeV LHC上,LHT粒子对$t\bar{t}$产生的贡献仅为1%左右。同时,Tevatron的反常顶夸克前后不对称性也很难用LHT模型解释。(2)在$t\bar{t}$产生中的宇称违反不对称性,例如左右不对称性$|A_{LR}|$和极化$|P_t|$可以分别达到1.1%和0.5%,这可能具有在LHC上提供LHT信号的潜力。
We study the Littlest Higgs model with T-parity (LHT) in the process of $pp \to W_H^+W_H^- \to W^+W^- A_H A_H$ at the 14 TeV LHC. With the $W$-jet tagging technique, we demonstrate that the bulk of the model parameter space can be probed at the level of more than $5σ$ in the signature of two fat $W$-jets plus large missing energy. Furthermore, we propose a novel strategy of measuring the principle parameter $f$ that is crucial to testify the LHT model and to fix mass spectrum, including dark matter particle. Our proposal can be easily incorporated into current experimental program of diboson s…
In the littlest Higgs model with T-parity(LHT), we study the single production of vector-like top partner with the subsequent decay $T_{+}\to Wb$ in the leptonic channel at the $ep$ colliders. Focus on the LHeC ($ \sqrt{s} $ = 1.98 TeV) and FCC-eh ($ \sqrt{s} $ = 5.29 TeV), we investigate the observability of the single top partner production with the unpolarized and polarized electron beams, respectively. As a result, the statistical significance can be enhanced by the polarized electron beams. Under the current constraints, the search for $T_{+}$ in the $Wb$ channel at the LHeC cannot provid…
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。
Motivated by the search for flavor-changing neutral current (FCNC) top quark decays at the LHC, we calculate rare Higgs three body decay $H\rightarrow Wbc$ induced by top-Higgs FCNC coupling in the littlest Higgs model with T-parity(LHT). We find that the branching ratios of $H\rightarrow Wbc$ in the LHT model can reach $\mathcal O(10^{-7})$ in the allowed parameter space.
In the littlest Higgs model with T-parity (LHT), we study the $t$-channel single top production in association with a Higgs boson at 8 and 14 TeV LHC. We find that the cross section can be enhanced obviously in this model compared to the Standard Model. By performing a simple parton-level simulation through $pp\rightarrow t(\rightarrow \ell^{+}νb)h(\rightarrow b\bar{b})j$ at 14 TeV LHC, we find that the observability of the signal is promising in the favorable parameter space.
The Littlest Higgs Model with T-parity (LHT) belongs to the simplest new physics scenarios with new sources of flavour and CP violation. We present a new analysis of quark observables in the LHT model in view of the oncoming flavour precision era. We use all available information on the CKM parameters, lattice QCD input and experimental data on quark flavour observables and corresponding theoretical calculations, taking into account new lower bounds on the symmetry breaking scale and the mirror quark masses from the LHC. We investigate by how much the branching ratios for a number of rare $K$ …
The top partner as a hallmark of the Littlest Higgs model with $T$-parity (LHT model) has been extensively searched for during the Large Hadron Collider (LHC) Run-1. With the increasing mass limits on the top partner, the single production of the top partner will be dominant over the pair production. Under the constraints from the Higgs data, the electroweak precision observables and $R_b$, we find that the mass of $T$-even top partner ($T_+$) has to be heavier than 730 GeV. Then, we investigate the observability of the single $T$-even top partner production through the process $pp \to T_+ j$ …
Within a mirror type assignment for the excited composite fermions the neutrino mass term is built up from a Dirac mass, $m_*$, which gives the mass of charged lepton component of the $SU(2)$, right-handed, doublet, and a Majorana mass, $m_L$, for the left-handed component (singlet) of the excited neutrino. The mass matrix is diagonalized leading to two Majorana mass eigenstates. The active neutrino field $ν^*_R$ is thus a superposition of the two mass eigenstates with mixing coefficients which depend on the ratio $m_L/m_*$. We discuss the prospects of discovery of these physical states at the…
Observation of non-zero neutrino masses at a scale $\sim 10^{-1} - 10^{-2}$ eV is a major problem in the otherwise highly successful Standard Model. The most elegant mechanism to explain such tiny neutrino masses is the seesaw mechanism with right handed neutrinos. However, the required seesaw scale is so high, $\sim 10^{14}$ GeV, it will not have any collider implications. Recently, an explicit model has been constructed to realize the seesaw mechanism with the right handed neutrinos at the electroweak scale. The model has a mirror symmetry having both the left and right lepton and quark doub…
We calculate the complete next-to-leading order (NLO) QCD corrections to the $T$-odd mirror quark pair ($q_-\bar q_-=u_-\bar u_-$, $c_-\bar c_-$, $d_-\bar d_-$, $s_-\bar s_-$) production in the littlest Higgs model with $T$-parity (LHT) at a high energy $γγ$ collider. We present the dependence of the leading order (LO) and NLO QCD corrected cross sections on the colliding energy $\sqrt{s}$. Our calculation includes the subsequent full weak decays of the final $T$-odd mirror quarks by adopting the narrow width approximation and the exclusive 2-jet event selection criterion. We provide the LO an…
我们探讨了“美丽的镜子”模型,该模型旨在解释$A^b_{FB}$的测量值,在$2.9σ$水平上的差异。这种情况引入了矢量状夸克,它们与底部混合,微妙地影响了它与$Z$的耦合。新粒子的光谱由两个底夸克和一个电荷为-4/3的夸克组成,它们都与第三代夸克有电弱相互作用。我们探讨的现象学和发现达到这些新粒子在大型强子对撞机,探索单镜夸克的生产模式,其速率是成比例的相同的混合参数,解决了$A_{FB}^b$异常。我们发现,对于镜像夸克质量,需要$\lesssim 500 GeV, a 14 TeV LHC with 300 {\rm fb}^{-1}$来合理地建立场景并提取相关的混合参数。
The existence of mirror partners of Standard-Model fermions offers a viable alternative to a fundamental BEH mechanism, with the coupling corresponding to the gauged mirror generation symmetry becoming naturally strong at energies around 1 TeV. The resulting non-perturbative processes produce dynamical katoptron masses which might range from 0.1 to 1.15 TeV in a way circumventing usual problems with the S parameter. Moreover, they create mirror mesons belonging in two main groups, with masses differing from each other approximately by a factor of six and which might range approximately from 0.…
We perform the one-loop induced charged lepton flavor violating decays of the neutral Higgses in an extended mirror fermion model with non-sterile electroweak-scale right-handed neutrinos and a horizontal $A_4$ symmetry in the lepton sector. We demonstrate that for the 125 GeV scalar $h$ there is tension between the recent LHC result ${\cal B}(h \to τμ) \sim $ 1% and the stringent limits on the rare processes $μ\to e γ$ and $τ\to (μ$ or $e) γ$ from low energy experiments.
We consider the collider signals arising from kinetic mixing between the hypercharge gauge boson of the Standard Model and its twin counterpart in the Mirror Twin Higgs model, in the framework in which the twin photon is massive. Through the mixing, the Standard Model fermions acquire charges under the mirror photon and the mirror Z boson. We determine the current experimental bounds on this scenario, and show that the mixing can be large enough to discover both the twin photon and the twin Z at the LHC, or at a future 100 TeV hadron collider, with dilepton resonances being a particularly cons…
We present a UV completion of the twin Higgs idea in the framework of holographic composite Higgs. The SM contribution to the Higgs potential is effectively cut off by the SM-singlet mirror partners at the sigma-model scale f, naturally allowing for m_{KK} beyond the LHC reach. The bulk symmetry is SU(7) X SO(8), broken on the IR brane into SU(7) X SO(7) and on the UV brane into (SU(3) X SU(2) X U(1))^{SM} X (SU(3) X SU(2) X U(1))^{mirror} X Z2. The field content on the UV brane is the SM, extended by a sector transforming under the mirror gauge group, with the Z2 exchanging the two sectors. A…
Solutions to the hierarchy problem usually require top partners. In standard SUSY or composite Higgs theories, the partners carry SM color and are becoming increasingly constrained by LHC searches. However, theories like Folded SUSY (FS), Twin Higgs (TH) and Quirky Little Higgs (QLH) introduce uncolored top partners, which can be SM singlets or carry electroweak charge. Their small production cross section left doubt as to whether the LHC can effectively probe such scenarios. Typically, these partners are charged under their own mirror color gauge group. In FS and QLH, the absence of light mir…
We perform an updated analysis for the one-loop induced lepton flavor violating radiative decays $l_i \to l_j γ$ in an extended mirror model. Mixing effects of the neutrinos and charged leptons constructed with a horizontal $A_4$ symmetry are also taken into account. Current experimental limit and projected sensitivity on the branching ratio of $μ\to e γ$ are used to constrain the parameter space of the model. Calculations of two related observables, the electric and magnetic dipole moments of the leptons, are included. Implications concerning the possible detection of mirror leptons at the LH…