Search for long-lived particles decaying into displaced dilepton vertices in proton-proton collisions at √s = 13 TeV with the CMS detector

  1. Fernández Madrazo, Celia
Supervised by:
  1. Pablo Martínez Ruiz del Árbol Director
  2. Celso Martínez Rivero Co-director

Defence university: Universidad de Cantabria

Fecha de defensa: 11 July 2023

Committee:
  1. Santiago Folgueras Gómez Chair
  2. Alicia Calderón Secretary
  3. Viatcheslav Valouev Committee member

Type: Thesis

Teseo: 818229 DIALNET lock_openTESEO editor

Abstract

Some of the most popular extensions of the Standard Model contain long-lived particles. This thesis presents a search for long-lived particles decaying into final states with a displaced dilepton vertex. It analyzes proton-proton collisions at a center-of-mass energy of 13 TeV that were produced at the CERN LHC and collected by the CMS detector in 2016, 2017 and 2018. Leptons in this analysis emerge from a vertex displaced from the interaction point and need to be reconstructed with special algorithms. The search is designed to cover a wide mass range, and be sensitive to lifetimes from 0.1 cm to 1000 cm. In the analysis, observed data are found to be in good agreement with the Standard Model expectations. Upper limits have been obtained for a model with an exotic Higgs boson decaying into two scalar long-lived particles. These results are competitive with similar results shown by the CMS and ATLAS collaborations, and in particular they provide the most stringent limits for the electron channel.