Abstract
Results are reported from a search for the pair production of top squarks, the supersymmetric partners of top quarks, in final states with jets and missing transverse momentum. The data sample used in this search was collected by the CMS detector and corresponds to an integrated luminosity of 18.9,text {fb}^text {-1} of proton-proton collisions at a centre-of-mass energy of 8;text {TeV} produced by the LHC. The search features novel background suppression and prediction methods, including a dedicated top quark pair reconstruction algorithm. The data are found to be in agreement with the predicted backgrounds. Exclusion limits are set in simplified supersymmetry models with the top squark decaying to jets and an undetected neutralino, either through a top quark or through a bottom quark and chargino. Models with the top squark decaying via a top quark are excluded for top squark masses up to 755;text {GeV} in the case of neutralino masses below 200;text {GeV}. For decays via a chargino, top squark masses up to 620;text {GeV} are excluded, depending on the masses of the chargino and neutralino.
Highlights
The standard model (SM) of particle physics is an extremely powerful framework for the description of the known elementary particles and their interactions
With event characteristics of these signals in mind, we have developed a search for pair production of top squarks with decays that result in a pair of lightest SUSY particle (LSP) in the final state in addition to SM particles
Note that these figures are for illustrative purposes only, and so some minor uncertainties in event yields in the more inclusive regions did not receive the detailed treatment applied to the uncertainties in the final search region yields
Summary
The standard model (SM) of particle physics is an extremely powerful framework for the description of the known elementary particles and their interactions. The second criterion relies upon the identification of top quark decay products to eliminate such backgrounds as SM production of W bosons in association with jets Together, these criteria define a preselection region consisting of events that pass stringent vetoes on the presence of charged leptons, and are required to have large ETmiss, two tagged b quark jets, and four additional jets from the hadronisation and decay of light quarks. These criteria define a preselection region consisting of events that pass stringent vetoes on the presence of charged leptons, and are required to have large ETmiss, two tagged b quark jets, and four additional jets from the hadronisation and decay of light quarks In spite of these stringent requirements, the low production cross sections of new physics signals mean that they are overwhelmed by SM backgrounds.
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