CMS
The records proton collisions from the Large Hadron Collider (LHC) at in Geneva, Switzerland. We use these high energy collisions to search for new fundamental particles, new particle interactions, and to measure fundamental parameters of nature with unprecedented precision. Ìý
The University of Colorado CMS group is led faculty members: , , , , and (emeritus). Our group is active in a range of projects spanning searches in the CMS data for evidence of physics beyond Standard Model and cutting edge detector and technology developments for future detectors.Ìý
CMS Searches for New Physics
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Dark Matter Astronomical observations suggest that ~80% of the matter in the universe is of unknown origin. Our group is searching for this "dark matter" in LHC collisions by looking for traditional signatures such as missing energy as well as more exotic signatures such as emerging jets. These efforts are led by Profs. Stenson, Ulmer, and Ford.Ìý
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Higgs Boson Studies The discovery of the Higgs boson in 2012 by the CMS and ATLAS experiments confirmed the Higgs mechanism for generating particle masses and completed the Standard Model of particle physics. The CU CMS group is now searching for evidence of the production of two Higgs bosons in the same event in the b,b tau,tau final state. This would confirm the Higgs boson's ability to couple to itself. This effort is led by Prof. Cumalat.
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Lepton Flavor Violation Lepton flavor universality holds that electrons, muons, and taus all have identical couplings to other Standard Model particles. We are testing this fundamental assumption in precision measurements of B meson decays (Rk ratio) and in searches for rare decays of Z bosons to different flavor leptons. Profs. Ulmer, Stenson, and Ford lead this effort.
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Model Independent Searches In this technique we employ a machine learning approach known as unsupervised learning to select CMS collision events that are the most "anomalous" compared to the full dataset. Within these events, we search for new particle resonances without any bias from a specific new physics model. This search is led by Profs. Ulmer and Stenson.
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CMS Detector Upgrade Projects
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Hardware-Level Track Trigger The LHC delivers such extreme data rates that CMS must select only a very small fraction of the data to record. This is done with real-time event reconstruction performed in FPGAs. The CU group is working to add charged particle tracking to this real-time event reconstruction for the first time at the LHC. This effort is led by Profs. Stenson and Ulmer.
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Silicon Sensor Electronics The most precise position measurements made at CMS are from the silicon pixel detector. This semiconducting detector tracks charged particles that pass through with sensitive readout electronics. The CU group is working to evaluate radiation hardness for HL-LHC sensor and electronics. This effort is led by Profs. Wagner and Cumalat.
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Anomaly Detection Triggers This effort extends the real-time CMS event reconstruction algorithms to include a machine learning approach known as anomaly detection. A variational autoencoder neural network implemented in firmware is trained to select events with distinct features in an unsupervised way without telling the algorithm what the unique features should be. This effort is led by Profs. Ulmer and Stenson.
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