Search

Since announcement of the muon $g-2$ anomaly, plenty of papers have devoted to this anomaly. The approximate formulae are always adopted when determining the new physics contributions to $(g-2)_{\mu}$, while clear scope of applications are always absent. This manuscript is dedicated to the comprehensive analytical results and approximations for the canonical interactions at one-loop level, which can be a useful handbook for the model builders. Here, we only collect the analytic and approximate expressions for the scalar mediator case. For the expressions of vector mediator case, they will appear in the future., Comment: 25 pages, 1 captioned figure, 2 tables. This manuscript will continue to be updated. Suggestions and comments are welcome

Leptoquark (LQ) models are well motivated solutions to the $(g-2)_{\mu}$ anomaly. In the minimal LQ models, only specific representations can lead to the chiral enhancements. For the scalar LQs, the $R_2$ and $S_1$ can lead to the top quark chiral enhancement. For the vector LQs, the $V_2$ and $U_1$ can lead to the bottom quark chiral enhancement. When we consider the LQ and vector-like quark (VLQ) simultaneously, there can be more scenarios. In our previous work, we considered the scalar LQ and VLQ extended models with up-type quark chiral enhancement. Here, we study the scalar LQ and VLQ extended models with down-type quark chiral enhancement. We find two new models with $B$ quark chiral enhancement, which originate from the bottom and bottom partner mixing. Then, we propose new LQ and VLQ search channels under the constraints of $(g-2)_{\mu}$., Comment: 17 pages, 2 captioned figures, 4 tables. Sequel to the paper arXiv:2112.13490 [hep-ph]. Add figures to show the $(g-2)_{\mu}$ allowed regions in the plane of $m_B-m_{\mathrm{LQ}}$. References added. Typos corrected. Presentation improved. Match the published version in Chinese Physics C

In minimal leptoquark (LQ) models, the $R_2$ and $S_1$ can be the solution to the $(g-2)_{\mu}$ anomaly because of the chiral enhancements. Here, we study the LQ and vectorlike quark (VLQ) extended models. In the one LQ and one VLQ extended models, the $(g-2)_{\mu}$ can receive the contributions from top and top partner $T$ because of the $t-T$ mixing. Besides the traditional $R_2$ and $S_1$ representations, we find that the $S_3$ LQ can also explain the anomaly when including the $(X,T,B)_{L,R}$ triplet at the same time. Moreover, we find that the LQ has the new decay channel $T\mu$ in these models., Comment: 6 pages, 1 captioned figure, 4 tables. Based on the paper arXiv:2112.13490 [hep-ph]. Online talk presented at the 41st International Conference on High Energy Physics - ICHEP2022 (6-13 July, 2022, Bologna, Italy). Accepted for publication in Proceedings of Science

The CDF collaboration recently announced a new measurement result of the $W$ boson mass, and it is in tension with the standard model (SM) prediction. In this paper, we explain this anomaly in the vector-like quark (VLQ) $(X,T,B)_{L,R}$ and leptoquark (LQ) $S_3$ extended model. In this model, both the VLQ and LQ have positive corrections to the $W$ boson mass. Moreover, it can also be a solution to the $(g-2)_{\mu}$ anomaly because of the chiral enhancements from top, $T$, and $B$ quarks., Comment: 26 pages, 4 captioned figures. Add the $U$ parameter contributions. Consider the constraints from electroweak precision observables. Typos corrected. References updated. Presentation improved. Match the published version in Chinese Physics C

Leptoquark (LQ) models can be the solution to the $(g-2)_{\mu}$ anomaly because of the chiral enhancements. In this work, we consider the models extended by the LQ and vector-like quark (VLQ) simultaneously, which can be used to explain the anomaly because of the top quark and top partner (denoted as $T$) mixing. For the one LQ and one VLQ extended models, there are contributions from the top and $T$ quark. In the minimal LQ models, only the $R_2$ and $S_1$ representations can lead to the chiral enhancements. Here, we find one new $S_3$ solution to the anomaly in the presence of $(X,T,B)_{L,R}$ triplet. We also consider the one LQ and two VLQ extended models, which can solve the anomaly even in the absence of top interactions and mixings. Then, we propose new LQ search channels under the constraints of $(g-2)_{\mu}$. Besides the traditional $t\mu$ decay channel, the LQ can also decay into $T\mu$ final states, which will lead to the characteristic multi-top and multi-muon signals at hadron colliders., Comment: 32 pages, 11 figures, 8 tables. We consider the contributions from bottom-type quark interactions, which are essential especially in the $R_2/S_3+(X,T,B)_{L,R}$ models. Footnotes added. Other minor corrections. Comments are welcome

Top partners are well motivated in many new physics models. Usually, vector like quarks $T_{L,R}$ are introduced to avoid the quantum anomaly. It is crucial to probe their interactions with the standard model particles. However, flavor changing neutral couplings are always difficult to detect directly in the current and future experiments. In this paper, we will show how to constrain the flavor changing neutral Yukawa coupling $Tth$ through the di-Higgs production indirectly. We consider the simplified model including a pair of gauge singlet $T_{L,R}$. Under the perturbative unitarity and experimental constraints, we choose $m_T=400~\mathrm{GeV},s_L=0.2$ and $m_T=800~\mathrm{GeV},s_L=0.1$ as benchmark points. After the analysis of amplitude and evaluation of the numerical cross sections, we find that the present constraints from di-Higgs production have already surpassed the unitarity bound because of the $(y_{L,R}^{tT})^4$ behavior. For the case of $m_T=400~\mathrm{GeV}$ and $s_L=0.2$, $\mathrm{Re}y_{L,R}^{tT}$ and $\mathrm{Im}y_{L,R}^{tT}$ can be bounded optimally in the range $(-0.4, 0.4)$ at HL-LHC with $2\sigma$ CL. For the case of $m_T=800~\mathrm{GeV}$ and $s_L=0.1$, $\mathrm{Re}y_{L,R}^{tT}$ and $\mathrm{Im}y_{L,R}^{tT}$ can be bounded optimally in the range $(-0.5, 0.5)$ at HL-LHC with $2\sigma$ CL. The anomalous triple Higgs coupling $\delta_{hhh}$ can also affect the constraints on $y_{L,R}^{tT}$. Finally, we find that the top quark electric dipole moment can give stronger bounds of $y_{L,R}^{tT}$ in the off-axis regions for some scenarios., Comment: 30 pages, 8 figures, and 5 tables. References added and typos corrected. Comments are welcome

With the deeper study of Higgs particle, Higgs precision measurements can be served to probe new physics indirectly. In many new physics models, vector-like quarks $T_L,~T_R$ occur naturally. It is important to probe their couplings with standard model particles. In this work, we consider the singlet $T_L,~T_R$ extended models and show how to constrain the $Tth$ couplings through the $h\rightarrow\gamma Z$ decay at high-luminosity LHC. Firstly, we derive the perturbative unitarity bounds on $|y_{L,~R}^{tT}|$ with other couplings set to be zeros simply. To optimize the situation, we take $m_T$ = 400 GeV and $s_L$ = 0.2 considering the experimental constraints. Under this benchmark point, we find that the future bounds from $h\rightarrow\gamma Z$ decay can limit the real parts of $y_{L,~R}^{tT}$ in the positive direction to be O(1) because of the double enhancement. For the real parts of $y_{L,~R}^{tT}$ in the negative direction, it is always surpassed by the perturbative unitarity. Moreover, we find that the top quark electric dipole moment can give stronger bounds (especially the imaginary parts of $y_{L,~R}^{tT}$) than the perturbative unitarity and $h\rightarrow\gamma Z$ decay in the off-axis regions for some scenarios., Comment: 30 pages, 9 figures. Show the top quark EDM and $h\rightarrow\gamma Z$ constraints in the same figure. Typos corrected. References added. Match the published version in PRD. Comments are welcome

In models where the Higgs is realized as a pseudo-Nambu-Goldstone boson (pNGB) of some global symmetry breaking, there are often remaining pNGBs of some $U(1)$ groups (called `pseudo-axions'), which could lead to smoking gun signatures of such scenarios and provide important clues on the electroweak symmetry breaking mechanism. As a concrete example, we investigate the phenomenology of the pseudo-axion in the anomaly-free Simplest Little Higgs (SLH) model. After clarifying a subtle issue related to the effect of symmetric vector-scalar-scalar (VSS) vertices (e.g. $Z_\mu(H\partial^\mu\eta+\eta\partial^\mu H)$), we show that for natural region in the parameter space, the SLH pseudo-axion is top-philic, decaying almost exclusively to a pair of top quarks. The direct and indirect (i.e. via heavy particle decay) production of such a pseudo-axion at the $14\,\mbox{TeV}$ (HL-)LHC turn out to suffer from either large backgrounds or small rates, making its detection quite challenging. A $pp$ collider with higher energy and luminosity, such as the $27\,\mbox{TeV}$ HE-LHC, or even the $100\,\mbox{TeV}$ FCC-hh or SppC, is therefore motivated to capture the trace of such a pNGB., Comment: 26 pages, 13 figures. Typos corrected, matched to journal version

We re-analyze the $ZH\eta$-vertex with the form $Z_{\mu}(\eta\partial^{\mu}H-H\partial^{\mu}\eta)$, where $H$ is the 125 GeV Higgs boson and $\eta$ is an exotic pseudo-axion, based on the effective field theory (EFT) analysis and choose the simplest little Higgs (SLH) model as an example. For a pure gauge singlet pseudoscalar $\eta$, after carefully removing all off-diagonal two-point transitions, we show that its coefficient $c_{ZH\eta}$ cannot appear before $\mathcal{O}(\xi^3)$ level, where $\xi$ is the ratio between the electro-weak scale $v$ and a high scale $f$. The same behavior arises in the simplest little Higgs (SLH) model, which is quite different from the result that has already existed for a long time., Comment: Talk at the 53rd Rencontres de Moriond (EW 2018); 6 pages; presentation (especially the abstract part) refined

We analyze the scalar potential of the Simplest Little Higgs (SLH) model in an approach consistent with the spirit of continuum effective field theory (CEFT). By requiring correct electroweak symmetry breaking (EWSB) with the $125\,\text{GeV}$ Higgs boson, we are able to derive a relation between the pseudo-axion mass $m_\eta$ and the heavy top mass $m_T$, which serves as a crucial test of the SLH mechanism. By requiring $m_\eta^2>0$ an upper bound on $m_T$ can be obtained for any fixed SLH global symmetry breaking scale $f$. We also point out that an absolute upper bound on $f$ can be obtained by imposing partial wave unitarity constraint, which in turn leads to absolute upper bounds of $m_T\lesssim 19\,\text{TeV}, m_\eta\lesssim 1.5\,\text{TeV}$ and $m_{Z'}\lesssim 48\,\text{TeV}$. We present the allowed region in the three-dimensional parameter space characterized by $f,t_\beta,m_T$, taking into account the requirement of valid EWSB and the constraint from perturbative unitarity. We also propose a strategy of analyzing the fine-tuning problem consistent with the spirit of CEFT and apply it to the SLH. We suggest that the scalar potential and fine-tuning analysis strategies adopted here should also be applicable to a wide class of Little Higgs and Twin Higgs models, which may reveal interesting relations as crucial tests of the related EWSB mechanism and provide a new perspective on assessing their degree of fine-tuning., Comment: 35 pages, 7 figures

The issue of deriving $ZH\eta$ vertex in the simplest Little Higgs (SLH) model is revisited. Special attention is paid to the treatment of non-canonically-normalized scalar kinetic matrix and vector-scalar two-point transitions. We elucidate a general procedure to diagonalize a general vector-scalar system in gauge theories and apply it to the case of SLH. The resultant $ZH\eta$ vertex is found to be different from those which have already existed in the literature for a long time. We also present an understanding of this issue from an effective field theory viewpoint., Comment: Accepted version by PRD; 11 pages with two columns; Presentation of Sec. II refined; EFT analysis added in Sec. IIIC; References updated

Though the 125 GeV Higgs boson is consistent with the standard model (SM) prediction until now, the triple Higgs coupling can deviate from the SM value in the physics beyond the SM (BSM). In this paper, the radiative correction to the triple Higgs coupling is investigated in the minimal extension of the SM by adding a real gauge singlet scalar. In this model there are two scalars $h$ and $H$, and both of them are mixing states of the doublet and singlet. Provided that the mixing angle is set to be zero, namely the SM limit, $h$ is the pure left-over of the doublet and its behaviour is the same as that of the SM at the tree level. However the loop corrections can alter $h$-related couplings. In this SM limit case, the effect of the singlet $H$ may show up in the $h$-related couplings, especially the triple $h$ coupling. Our numerical results show that the deviation is sizable. For $\lambda_{\Phi{S}}=1$ (see the text for definition), the deviation $\delta_{hhh}^{(1)}$ around threshold can be more than $20\%$ if mass of the new scalar is light. For $\lambda_{\Phi{S}}=1.5,3$, the deviation $\delta_{hhh}^{(1)}$ can reach above $30\%$ in the vicinity of threshold. For $\lambda_{\Phi{S}}=-1$, $m_H$ can be light. The deviation $\delta_{hhh}^{(1)}$ is negative in this case and can be even $-50\%$ in the threshold enhanced region. The radiative correction for the $hZZ$ coupling is from the counter-term, which is universal in this model and always with negative sign. $\delta_{hZZ}^{(1)}$ is independent of the sign of $\lambda_{\Phi{S}}$ and its typical size is $-0.2\%\sim-2\%$. When combining $hhh$ and $hZZ$ precision measurements together, parameter space of this model can be probed well including the sign and size of $\lambda_{\Phi{S}}$., Comment: 23 pages, 22 figures. Parameter space constraints from vacuum global minimum added, analytical results unchanged, more numerical results added. Comments are welcoming