Physics (Internal)

Searches for New Physics with Boosted Top Quarks and the CMS Forward Pixel Detector Phase 1 Upgrade Mechanics

This event is part of the HEE Seminar Series.

Many “beyond the Standard Model" (BSM) models introduced to solve the hierarchy problem involve quantum interactions with top quarks to mitigate the increase in mass of the Higgs boson. Hence, new physics signatures involving the Top quark are good candidates for this puzzle. We search for new physics at the LHC with the CMS detector in the form of a massive particle decaying to a pair of top quarks. For large masses, these top quarks will be highly boosted, leading to unique event topologies with merged top decay products. We utilize jet substructure and subjet b-tagging techniques to identify these events, and proceed to set limits on the possible cross sections of new physics models. Currently LHC runs at the luminosity of 34 cm-2s-1. In 2017 the luminosity of the LHC will also be upgraded to 2E34 cm-2s-1, providing physicists a greater opportunity to seek answers to some of the particle physics mysteries we have encountered since the inception of the LHC. A new pixel detector for the CMS experiment is currently under construction, to be installed during the extended year end shutdown 2017. The pixel detector, the core of the CMS detector, was commissioned in 2008 and is so far running successfully. However the higher instantaneous luminosity will cause unacceptable dynamic inefficiencies due to buffer overflows. The more complex track pattern recognition due to higher pileup will require an additional pixel detector layer to maintain good efficiency. The Phase 1 pixel detector replacement addresses these shortcomings. To add an additional detector layer without adding material required a complete redesign of the mechanical support and cooling using novel materials.