EXPANDING THE HEP FRONTIER WITH BOOSTED B-TAGS AND THE QCD POWER SPECTRUM

As particle physics continues to expand into the high-energy and highluminosity frontiers, it is encountering event topologies with extreme boosts and intense pileup. This creates unique challenges that limit our ability to use QCD jets to find new physics and conduct precision tests of the standard model. In this thesis, I present two tools that greatly expand our ability to use jets for these important purposes: (i) The μx boosted-bottom jet tag, whose O(100) signal to background ratio does not falter as jet pT exceeds 1TeV, and which is robust to pileup due to its foundation in boosted kinematics. (ii) Power jets, the first stage in a larger program to harness the power spectrum of QCD radiation to better utilize the vast amount of information collected about each collider event. Using the full power spectrum of a detected event, the power jets framework not only provides an accurate and precise recovery of jet kinematics, but also naturally facilitates a global fit to pileup intensity (rather than a local subtraction of pileup energy, which inadvertently strips soft QCD that belongs to the hard scatter).Ph.D. in Physics, May 201