$ZH\hat{I}\cdot$-vertex: EFT Analysis and the Behavior in the SLH Model

Abstract

We re-analyze the $ZH\hat{I}\cdot$-vertex with the form $Z_{\hat{I}}¼(\hat{I}\cdot {\partial }^{\hat{I}}¼H-H{\partial }^{\hat{I}}¼\hat{I}\cdot )$, where $H$ is the 125 GeV Higgs boson and $\hat{I}\cdot$ 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 $\hat{I}\cdot$, after carefully removing all off-diagonal two-point transitions, we show that its coefficient $c_{ZH\hat{I}\cdot }$ cannot appear before $\mathcal{O}(\hat{I}{¾}^3)$ level, where $\hat{I}¾$ 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.

Talk at the 53rd Rencontres de Moriond (EW 2018); 6 pages; presentation (especially the abstract part) refined