Search for top squarks decaying via four-body or chargino-mediated modes in single-lepton final states in proton-proton collisions at √s=13 TeV

• Main Authors: Sirunyan, A. M., Tumasyan, A. R., Adam, Wolfgang, Ambrogi, Federico, Asilar, Ece, Md. Ali, Mohd. Adli
• Format: Article
• Language: English; English
• Published: Springer Nature 2018
• Subjects: Q Science (General); QC Physics
• Online Access: http://irep.iium.edu.my/70394/1/70394_Search%20for%20top%20squarks%20decaying%20via%20four-body_article.pdf; http://irep.iium.edu.my/70394/2/70394_Search%20for%20top%20squarks%20decaying%20via%20four-body_scopus.pdf; http://irep.iium.edu.my/70394/; https://link.springer.com/content/pdf/10.1007%2FJHEP09%282018%29065.pdf

A search for the pair production of the lightest supersymmetric partner of the top quark (et1) is presented. The search focuses on a compressed scenario where the mass difference between the top squark and the lightest supersymmetric particle, often considered to be the lightest neutralino (χe 0 1 ), is smaller than the mass of the W boson. The proton-proton collision data were recorded by the CMS experiment at a centre-of-mass energy of 13 TeV, and correspond to an integrated luminosity of 35.9 fb−1 . In this search, two decay modes of the top squark are considered: a four-body decay into a bottom quark, two additional fermions, and a χe 0 1 ; and a decay via an intermediate chargino. Events are selected using the presence of a high-momentum jet, significant missing transverse momentum, and a low transverse momentum electron or muon. Two analysis techniques are used, targeting different decay modes of the et1: a sequential selection and a multivariate technique. No evidence for the production of top squarks is found, and mass limits at 95% confidence level are set that reach up to 560 GeV, depending on the m(et1) − m(χe 0 1 ) mass difference and the decay mode.