New Physics Models And The Left-right Asymmetry Observables

In Jul.2012, the ATLAS and CMS collaborations have independently reported the dis-covery of a neutral scalar particle that seems consistent with the standard model Higgs boson with a mass of around126GeV at the LHC. The discovery of the Higgs boson does not mean the end of particle physics, because there remain problems which cannot be explained within the framework of the Standard Model (SM) such as the hierarchy problem, the tiny but nonzero neutrino masses etc. In order to solve the series of problems and probe the property of Higgs further, new physics models beyond the SM (BSM) are needed.Being the heaviest fermion ever known, the top quark has many unique features and it is thought to be closely related with new physics BSM. This thesis mainly introduces top quark asymmetry observables, including the top-quark forward-backward asymmetry, charge asym-metries and left-right asymmetry etc. In chapter two, it explains a new definition of charge asymmetry in top pair production at the LHC, namely the edge charge asymmetry. Addition-ally, chapter three introduces two new observables-incline asymmetry and energy asymmetry to measure the charge asymmetry in hadronic top pair production in association with a hard jet. The incline asymmetry based on the inclination between the planes of initial-and final-state momenta, probes the charge asymmetry in the quark-antiquark channel; the energy asymmetry which is defined as the energy difference between top and antitop quarks is used to probing the charge asymmetry in the quark-gluon channel at the LHC.Our study in chapter four focuses on four new physics models and top polarization left-right asymmetry AlLR. We calculate their left-and right-handed hadronic cross sections σL and σR and the AlLR in the contexts of the top triangle moose (TTM) model, left-right twin Higgs (LRTH) model, Higgs triplet model (HT M), and the3-3-1model with right-handed neutrinos (3-3-1RHN). The AlLR related to the processes ppâ†'tS±, in which S±represent the charged scalars, is almost free from theoretical uncertainties. At last, we discuss the possibility of discriminating these new physics models via measuring these observables at the LHC.