The Study Of The Top Squark Production Via The Electroweak Interaction Processes At The Hadron Collider

The Standard Model(SM)has been a great success in describing the micro-world of elementary particles.However,due to lack of the dark matter candidate and having the hierarchy problem,the SM is widely believed to be a low energy effective theory.The new physics beyond the SM will emerge at the TeV scale.The supersymmetry(SUSY)is one of the most promising extensions of the SM.Among the supersymmetric particles predicted by SUSY,the top quark partners,namely stops,play a crucial role in canceling the quadratic divergence of the top quark loop,and thus protect the Higgs mass at the electroweak(EW)scale.Therefore,searching for the stops is a vital task to test SUSY naturalness.Usually,the study of the stop is based on the stop pair production,which is generally regarded as a sensitive way to search for the stop at the LHC.Besides,the stop can also be produced via electroweak interaction.As a comparison with the pair production,the single production of stop will be helpful to understand the EW properties of stop.In this thesis,we investigated the observability of the mono-bottom events from the single stop production in natural Minimal Supersymmetric Standard Model(MSSM)at the HL-LHC and HE-LHC.Through the Monte Carlo simulations,we found that:·The higgsino mass parameters were taken μ=100,200,300 GeV.When the stop mass is heavier than about 2.2 TeV and 3.3 TeV,the single stop production have a larger production rate than the stop pair production at 14 TeV and 27 TeV LHC;·The stop mass can be excluded up to roughly 1.25 TeV at 2a at the LHC with(?)=14 TeV and integrated luminosity of 3000 fb-1.The LHC with(?)=27 TeV and integrated luminosity of 15 ab-1 is capable of discovering the stop mass and the higgsino mass up to 1.6 TeV and 550 GeV at 5a.If no excess events were observed,the 2a exclusion limits of the stop mass can reach around 1.9 TeV.Given that the project of hadron-hadron collider at a centre-of-mass energy of 100 TeV has long been under consideration and extensively studied,such as the Super Proton-Proton Collider(SPPC),the discovery potential for new physics would be increased largely with its high collision energy.So,we also studied the mono-top and mono-bottom signa-tures of the single stop production in natural MSSM at the hadron collider of 100 TeV.We found that:·In compressed electroweakino scenario,for wino-like χ1± the cross section of the left-handed stop production is larger than the right-handed stop.However,for higgsino-like χ1± the cross section of the right-handed stop single production is much larger.In addition,the cross section of the right-handed stop is independent of tan β,but the left-handed stop is not·The stop mass can be probed up to 3.2 TeV and 1.8 TeV at 5a statistical significance by the mono-top and mono-bottom channels at the 100 TeV hadron collider with integrated luminosity of 3000 fb-1,while the exclusion limits are 3.85 TeV and 2.55 TeV,respectively.