Abstract
Abstract The main background for the supersymmetric stop direct production search comes from Standard Model $ t\overline t $ events. For the single-lepton search channel, we introduce a few kinematic variables to further suppress this background by focusing on its dileptonic and semileptonic topologies. All are defined to have end points in the background, but not signal distributions. They can substantially improve the stop signal significance and mass reach when combined with traditional kinematic variables such as the total missing transverse energy. Among them, our variable $ M_{{T2}}^W $ hasthebestoverallperformancebecause it uses all available kinematic information, including the on-shell mass of both W’s. We see 20 %-30 % improvement on the discovery significance and estimate that the 8 TeV LHC run with 20 fb−1 of data would be able to reach an exclusion limit of 650-700 GeV for direct stop production, as long as the stop decays dominantly to the top quark and a light stable neutralino. Most of the mass range required for the supersymmetric solution of the naturalness problem in the standard scenario can be covered.
Highlights
This is possible if the partner is charged under the symmetry that protects the stability of the dark matter particle
We expect an even higher mass reach for the stop search compared with the numbers obtained in the previous section based on 7 TeV
To estimate the exclusion or discovery sensitivity of the stop with a 20 fb−1 luminosity, we calculated the stop signal cross sections at tree level using MadGraph5 and applying the same K-factor at the 7 TeV LHC to take into account the QCD NLO corrections
Summary
We study the LHC search for the pair-production of stops, pp → t1t∗1, with t01 → t + χ1.1 We focus on the signal’s one-lepton decay channel, in which one top quark decays leptonically t → W +b → l+νl b and the other one decays hadronically t → ̄bjj ( the other way around). Each of the two MT 2 variables defined above did not fully utilize the information available for the background event topology: the two intermediate W bosons are on-shell and one of them produces the observed lepton together with a neutrino. We can define a new kinematic variable as the minimal mother particle mass (the top quark mass in this case) which can be compatible with all the transverse momentum and mass-shell constraints of that topology for a given event. [49] by generalizing the method there to this case For perfect measurements, this variable for the dileptonic ttbackgrounds is less than the true top quark mass since the top mass should be compatible with all background events. We will make a critical comparison of the performances of these variables and their combinations
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
