Inclusive Searches for Supersymmetry at √s = 13 TeV Using Razor Kinematic Variables, and Data Scouting Using the CMS Trigger System

Citation

Anderson, Dustin James (2018) Inclusive Searches for Supersymmetry at √s = 13 TeV Using Razor Kinematic Variables, and Data Scouting Using the CMS Trigger System. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/BHGN-VY70. https://resolver.caltech.edu/CaltechTHESIS:05162018-153827333

Abstract

We present two searches for supersymmetric particles using proton-proton collision data collected by the CMS experiment at √s = 13 TeV. The searches use razor kinematic variables for signal discrimination and target the pair production of heavy gluinos and squarks in R-parity conserving supersymmetry. The first search is performed on 2.3 fb⁻¹ of data collected by CMS in 2015. Two complete, independent background predictions are made: one based on fits using a parameterized functional form, and the other based on Monte Carlo simulation corrected via control samples in data. The second search is an expanded version of the first search, and is performed using the Monte Carlo-based background prediction method on 35.9 fb⁻¹ of data collected in 2016. Both searches obtain results compatible with standard model background expectations. The null results are interpreted as limits on the masses and cross sections of gluinos, squarks, and higgsinos in the context of simplified models of supersymmetry. We discuss the outlook for the fit-based search strategy and explore how the technique of gaussian process regression may be useful as a tool to combat the challenges of this analysis methodology.

We also describe a new paradigm for trigger-level collider data analysis, which we refer to as data scouting. In this paradigm, searches for new physics are performed using event information reconstructed within the experiment’s trigger software. This circumvents traditional event rate constraints, such as disk space and the latency of offline reconstruction. We provide details on the implementation of a framework for data scouting in the CMS High-Level Trigger system and its successful use in Run II of the LHC. We discuss the impact of scouting on the physics program of CMS and demonstrate that it enables searches for new physics that would not otherwise be possible due to trigger constraints, such as hadronic resonance searches at low mass and searches for leptonic decays of dark photons.

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