Thesis Defense |
Events During the Week of November 30th through December 7th, 2025
Monday, December 1st, 2025
- No events scheduled
Tuesday, December 2nd, 2025
- No events scheduled
Wednesday, December 3rd, 2025
- No events scheduled
Thursday, December 4th, 2025
- Measurement of the Three Top Quarks Process with the CMS Detector at the LHC
- Time: 10:00 am - 12:00 pm
- Place: 5280 Chamberlin
- Speaker: Dylan Teague, Physics PhD Graduate Student
- Abstract: This thesis presents the first analysis measuring the three top quark decay process at the Large Hadron Collider. The measurement was performed on events with two same-sign leptons and three or more leptons on data taken by the Compact Muon Solenoid detector during the 2016–2018 data taking period corresponding to 137 fb-1 of data with √𝑠 = 13 TeV. The analysis found the three top process to have an overall significance of 0.182𝜎 and a CLs 95 % upper limit of 28.1 fb. These results were also uses to reinterpret the data to place limits on possible beyond Standard Model physics models that predict enhancements to the three top quark cross-section.
- Host: Kevin Black
Friday, December 5th, 2025
- Study of ZZ+jets and Electroweak ZZ+2jets Production in Proton-Proton Collisions at √s = 13 TeV in Four-Lepton Events Using the CMS Detector at the LHC
- Time: 11:30 am - 1:30 pm
- Place: 5280 Chamberlin
- Speaker: He He, Physics PhD Graduate Student
- Abstract: Two studies are presented on di-boson production in association with jets in the fully leptonic final states, pp → (Z/γ∗)(Z/γ∗) + jets → 2ℓ2ℓ′ + jets, (ℓ, ℓ′ = e or μ) in proton-proton collisions at a center-of-mass energy of 13 TeV. The data sample corresponds to an integrated luminosity of 138 fb−1 collected with the CMS detector at the LHC. In the first study, search is performed for the electroweak (EW) production of two Z bosons in association with two jets (EW ZZ+2jets) using a deep neural network (DNN) approach, and the production is measured with an observed (expected) significance of 4.4 (3.4) standard deviations, consistent with the published CMS results based on a matrix element likelihood approach (MELA). In the second study, differential distributions and normalized differential cross sections of di-boson ZZ production associated with different numbers of jets (ZZ+jets) are measured as a function of jet multiplicity, transverse momentum pT, pseudorapidity η, invariant mass and ∆η of the highest-pT and second-highest-pT jets, and as a function of invariant mass of the four-lepton system for events with various jet multiplicities. These differential cross sections are compared with theoretical predictions that mostly agree with the experimental data. However, in a few regions we observe discrepancies between the predicted and measured values. Further improvement of the predictions is required to describe the ZZ+jets production in the whole phase space.
- Host: Matthew Herndon