384 research outputs found

    Investigation of Radiation Damage in Silicon Sensors for the Phase-2 Upgrade of the CMS Outer Tracker

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    Der CMS Outer Tracker wird f√ľr den Betrieb des HL-LHC vollst√§ndig ausgetauscht. Diese Arbeit besch√§ftigt sich mit den Bestrahlungstests im Zuge der Produktion neuer Siliziumstreifensensoren. Im zweiten Hauptteil wird die Streifenisolation von n-on-p Siliziumstreifensensoren n√§her beleuchtet. Hierbei wurde ebenfalls ein starker Fokus auf das Verhalten nach Bestrahlungen gesetzt. Zudem wurde ein TCAD Defektmodell entwickelt, um die Messungen reproduzieren und vorhersagen machen zu k√∂nnen

    Combined searches for the production of supersymmetric top quark partners in proton-proton collisions at root s=13 TeV

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    A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV

    Search for top squark production in fully hadronic final states in proton-proton collisions at root s=13 TeV