Search

We confront the little Higgs theory with the LHC Higgs search data (up to 17 fb-1 of the combined 7 and 8 TeV run). Considering some typical models, namely, the littlest Higgs model, the littlest Higgs model with T parity (LHT-A and LHT-B), and the simplest little Higgs model, we scan over the parameter space in the region allowed by current experiments. We find that in these models the inclusive and exclusive (via gluon-gluon fusion) diphoton and ZZ* signal rates of the Higgs boson are always suppressed and approach the standard model predictions for a large-scale /. Thus, the ZZ* signal rate is within the 1 σ range of the experimental data while the inclusive diphoton signal rate is always outside the 2a range. Especially, in the LHT-A the diphoton signal rate is outside the 3σ range of the experimental data for f < 800 GeV. We also perform a global Χ² fit to the available LHC and Tevatron Higgs data, and find that these models provide no better global fit to the whole data set (only for some special channels a better fit can be obtained, especially in the LHT-B). [ABSTRACT FROM AUTHOR]

In order to explain the Tevatron anomaly of the top quark forward-backward asymmetry AtFB in the leftright twin Higgs model, we choose to give up the lightest neutral particle of h field as a stable dark matter candidate. Then a new Yukawa interaction for hˆ is allowed, which can be free from the constraint of samesign top pair production and contribute sizably to AtFB. Considering the constraints from the production rates of the top pair (tt), the top decay rates, and «invariant mass distribution, we find that this model with such new Yukawa interaction can explain ApB measured at the Tevatron while satisfying the charge asymmetry AtC measured at the LHC. Moreover, this model predicts a strong correlation between AtC at the LHC and AFB at the Tevatron, i.e., AtC increases as Apg increases [ABSTRACT FROM AUTHOR]

As a top quark factory, the LHC can test new physics models used to explain the top quark forward-backward asymmetry A'FB measured at the Tevatron. In this work we perform a comparative study for two such models: the W' model and the color triplet diquark (ø) model. Requiring these models to explain A'FB and also satisfy the top pair production rate measured at the Tevatron, we examine their contributions to the LHC observables such as the polarizations and charge asymmetries in top quark productions and the charge asymmetry in W' (or ø) pair production. We find that these observables can be enhanced to their observable levels and current LHC measurement on the top charge asymmetry has already tightly constrained the W' model. We also find that each observable shows different characteristics in different models, which can be utilized to discriminate the models. [ABSTRACT FROM AUTHOR]