Signal And Background Analysis For Highly Boosted Hadronically Decaying Heavy Particles At LHC

To solve many problems in particle physics, we need a lot of high-energy experimentaldata with high precision. The LHC and the high-energy colliders in the future become the keyto solve these problems. Therefore, understanding some basic knowledge about the collideris very necessary. With the center of mass energy increasing, the experiments produce largesamples events with a transverse momentum pTthat considerably exceeds their rest mass m(pT m). In this new kinematic regime, well-known particles (such as W±、Z0、Top) areobserved in unfamiliar ways. Classical reconstruction algorithms that rely on a one-to-one jet-to-parton assignment are often inadequate, in particular for hadronic decays of such boostedobjects. A suite of techniques, i.e. the jet substructure has been developed to fully exploit theopportunities offered by boosted objects at the LHC. We will introduce this method and applyit to distinguish highly boosted hadronically decaying W’s (W-jets) from QCD-jets.We studied high energy W Z scattering by using jet substructure techniques and a multi-variate approach. Compared with previous methods, such as the filtering/mass-drop method,a multivariate approach including the shape of the W-jet,subjet planar flow, and grooming-sensitivities is shown to provide a much larger factor improvement in S/√B. This W-taggingtechnology can enhance the discrimination efficiency of the heavy particles from QCD back-groud, and improve the ability for searching highly boosted heavy particles at LHC.