Dark Matter and Track Triggering with the CMS Experiment

Breakthrough discoveries at the Energy Frontier require colliders capable of producing heavy new particles at significant rates. These capabilities are directly related to the energy and intensity (luminosity) of the colliding beams. Continued gains in beam energy and luminosity have driven progress in the field, culminating in the discovery of the long-sought Higgs boson in Run-1 of the CERN Large Hadron Collider (LHC). The LHC has now entered Run-2, at twice the collision energy of Run-1. Soon the LHC will undergo a series of upgrades that will increase beam intensity by almost a factor of 50 by 2025. The enhanced capabilities of the LHC and of the future, high-luminosity LHC (HL-LHC) will significantly extend the reach of searches for new physics. An exciting era of new discovery awaits. Amazingly little is known about the “Dark Matter” (DM) that represents more than 25% of the mass content of the universe. I propose to lead the exploration of DM in Run-2 by searching for its associated production with heavy standard model particles – W bosons and top quarks – with the Compact Muon Solenoid (CMS) experiment. When produced, DM particles escape the detector without interaction, giving rise to a significant “transverse missing energy” (Ɇ T) signal. The mono- W/monojet search I propose improves sensitivity to DM production by focusing on the high-yield hadronic W decay channels. The related t¯t + Ɇ T search, on which we will focus, is sensitive to couplings to heavy flavor, provides crucial sensitivity to spin-0 mediators, and can be understood within the same theoretical framework as the monojet/mono-V search. Any of these signatures could function as the primary DM discovery channel at the LHC. We will analyze and combine each of these search channels to maximize the potential for DM discovery in Run-2. The recent P5 report and the updated European Strategy for Particle Physics identify the HL-LHC as the highest near/medium-term priority for the particle physics community. The HL-LHC will deliver 3000 fb􀀀1, or 10 times the LHC luminosity integrated by the end of 2021. Direct searches for new particle production in CMS will gain sensitivity to multi-TeV masses and sub-femtobarn production cross sections. Sensitivity at these scales could be crucial for the detection of DM, which might only interact with known particles weakly, via a heavy mediator. The key enabler of HL-LHC physics goals will be a real-time \Level-1" (L1) tracking trigger. L1 trigger systems implement the first stage of data refinement in hadron collider experiments. These systems examine data from every beam crossing and have just microseconds to decide if collision data should be retained or discarded. The real-time nature of L1 trigger operation, coupled with the enormous data rates and computational power required for tracking, presents a daunting set of technical challenges. Partially because of its difficulty, silicon-based L1 tracking was never attempted in previous hadron collider experiments. Now, however, L1 track triggering is no longer elective { this capability will be essential for continued progress at the Energy Frontier. I propose to tackle the primary challenges of the CMS L1 tracking trigger project: the development of a high-bandwidth data distribution system, and the implementation of a low-latency, scalable track fitter.