Physics of elementary particles at high energies
My research deals with the interactions of elementary particles, the basic components of all matter. Many of these particles have not existed since the earliest seconds of the universe, but they can now be produced in collisions at very high energies. Previous measurement of the particle interactions leads us to believe they may be more complex than our current beautiful theories predict.I work on experiments at high-energy hadron colliders to measure particle properties and search for new phenomena, especially physics related to electroweak symmetry breaking (EWSB). The proposed theories of EWSB decribe how the fundamental particles acquire mass in gauge theories, and most predict new physics particles as a result of the symmetry breaking.
Currently I am collaborating on two experiments on the high-energy frontier.
ATLAS experiment at the Large Hadron Collider (CERN)
The ATLAS experiment, which will record data from proton-proton collisions at 14 TeV center-of-mass energy, will begin taking data in 2007. The LHC energy and beam intensities are much greater than those at the Tevatron, and we expect this will translate to increased production rates for exotic particles. In particular, the ATLAS detector will be sensitive to standard model Higgs boson production over a large allowed mass range, and we expect to test a wide range of supersymmetric models.
The greater energies and particle flux also presents a challenge for the ATLAS detector design. The outer regions of the detector are 15 meters from the interaction point, in order to measure more accurately the charged particles' trajectories. The inner detectors — silicon detectors with precise tracking capabilities — have been designed to withstand very high radiation doses. Nevertheless, work has begun to design a replacement which will be even more radiation-hard. The SCIPP ATLAS group is involved in research and development for this project.
CDF experiment at the Tevatron (Fermilab)
The CDF experiment has been taking data from proton-antiproton collisions at 1.96 TeV center-of-mass energy since 2001.
With the CDF detector, I am studying the properties of the top quark, which was discovered at Fermilab in 1995. The top quark is the most massive elementary particle — heavier even than a tungsten atom, and its enormous mass has led to speculation about whether it may play some rôle in EWSB.
Recent measurements of the top quark mass and production rate provide useful experimental input to such questions.