Thesis

Search for the supersymmetric partners of the top quark (stop) in compressed spectra at the Large Hadron Collider

• Call:

  IDPASC Portugal - PHD Programme 2014

• Academic Year:

  2014 /2015

• Domain:

  Experimental Particle Physics

• Supervisor:

  Pedrame Bargassa

• Co-Supervisor:

  Joao Varela

• Institution:

  Instituto Superior Técnico

• Host Institution:

  Laboratório de Instrumentação e Física Experimental de Partículas

• Abstract:

  The study aims at the search for the supersymmetric (SUSY) partner of the top quark (stop) with the CMS experiment at the LHC. SUSY partners of quarks & gluons, namely squarks & gluinos, are among the most accessible SUSY particles at the LHC. For every quark, the mass splitting between pairs of squarks is proportional to the Standard Model (SM) quark mass. Since the top is the heaviest SM quark, the lightest stop may be the lightest squark, thus the most easily observable at LHC. Stop searches are at present among the most exciting searches at the LHC.This search targets a scenario where the mass difference between the stop & the Lightest Susy Particle (LSP) is very small. The measure of the Cold Dark Matter (CDM) density gives a high preference to such compressed mass spectrum. This search will be led in the “lepton + missing energy + jets” final state, taking advantage of the expertise of the LIP CMS group in the LHC data with this signature. The kinematic spectra of the physics objects being very soft, this search opens the possibility for an approach innovative & complementary to other stop searches.