Collider Phenomenology Of New Physics Beyond The Standard Model

The discovery of the Higgs boson is another triumph for particle physics in describing the most fundamental interactions.However,there are still anomalous experimental results indicating that the Standard Model is not the final theory to explain all of the natural phenomena.With the preci-sion test of the Standard Model,we should also use collider experiments to look for the evidence of new physics beyond the Standard Model.In this work,we focus on the collider phenomenology of new physics models and their corresponding search strategies.We first study the TeV realization of neutrino mass models.In an inverse seesaw model with exotic leptons,their decay processes are very similar to the Standard Model W and Z bosons.We find pair-produced exotic leptons could fake WW events at the Large Hadron Collider.Probing lepton number violation is impor-tant for the test of Majorana neutrinos.We study the measurement of inverse neutrinoless double beta decay process at future electron-electron colliders.We choose event reconstruction methods and kinematic cuts in different channels,and find neutrinoless double beta decay could effectively constrain neutrino mixing parameters.Self-interacting dark matter is a compelling solution to the small-scale structure problem in astrophysics.We propose to search for dark matter bound states in collider experiments as a complementary test of dark matter self-interactions.In our model,bound states are formed by the dark photon exchange,and their annihilation into a pair of long-lived dark photons,which decay back into leptons,would lead to displaced lepton jet signals.We find this method could probe parameter regions favored by cosmological simulations.We use this strategy to fix self-interacting dark matter model parameters with the bound state search and astrophysicalobservations.We also study bound states formed by gluon exchange between new scalar particles.The signals of top squark bound states would be buried in the Standard Model backgrounds.For bound states of new particles with more electric charges,their annihilation decays could contribute to diphoton excess events at hadron colliders.We find the couplings of new scalars with quarks are constrained by collider search results,and only the decay into top quark plus light jet could survive.We study the kinematics in the top squark decay as well.By comparing the simulations of full matrix element method and kinematic method,we find polarization effects play an important role in cascade decays,and the final state kinematic efficiency could be significantly enhanced or suppressed.Using kinematic simulation could give an inaccurate estimate of cross section rate in supersymmetric particle searches.The application of machine learning in jet classification would improve the event selection process in future experiments.We use a fully-connected neural net-work to distinguish quark and gluon jets.Compared with current methods,this network could better classify high energy jets,and also work in various jet kinematic regions.We find jet observables are very useful in classification problems.