Lawrence K. Gibbons
Associate Professor of Physics
Director of Graduate Studies
B. A., 1985, University of Chicago. Ph.D., 1993, University of Chicago. Research Associate, University of Rochester, 1993-97. Assistant Professor, Physics, Cornell University, 1997-2004. Associate Professor, Physics, Cornell, 2004-present. Analysis Coordinator, CLEO Collaboration, 1996-97. Software Coordinator, CLEO III, 1997-2000. Member, American Physical Society.
Precision measurements, CP violation, weak interactions, electroweak symmetry breaking, heavy quark physics, experimental particle physics
My research interests center on precision measurements of fundamental parameters in particle physics. I am continuing these pursuits with the new “g-2” experiment, E989, planned to run at Fermilab in 2015. The experiment goals are a determination of the anomalous magnetic moment of the muons– that is, the deviation of its Landé g factor from 2 – to a precision of ~ 0.1 parts per million. At this level of precision, the measurement is sensitive to contributions to the magnetic moment from new fundamental particles outside of the Standard Model. The level of contribution of Beyond Standard Model processes to g-2 varies widely according to the nature of the model, and a g-2 measurement at the precision planned will therefore provide an excellent constraint on the nature of new particles that will be observed directly at the Large Hadron Collider (LHC). The heart of the experiment is the muon storage ring, and I am joined in the Cornell effort by Dave Rubin, who brings considerable accelerator physics expertise. I am involved in work with the detectors that will be used to measure the daughter electrons from the muon decays. The experiment is currently in its design stage, so a student joining now has the rare opportunity to be involved all stages of a modern High Energy Physics (HEP) experiment.
The Cornell HEP group’s major focus is the CMS experiment at the LHC. The LHC will be the first collider that will allow us to probe the processes involved in electroweak symmetry breaking, the process by which electromagnetism and the weak interaction come to appear so different at our day-to-day energy scale, and by which all the particles that we know obtain their mass. The collision energies will also be large enough that we may very well produce, and observe directly, new types of fundamental particles!
I am currently exploring techniques to measure the production charge asymmetry of the W bosons produced at CMS. This asymmetry directly probes the up and down quark and antiquark content of the proton, which must be understood extremely well to find new fundamental particles at the LHC and measure their properties. I am also part of a small Cornell group that has been developing a powerful new tool for use in LHC physics analyses, the “MET significance”. A common feature of the new processes that we night to find at the LHC are that they often involve production of massive particles that escape without detection because they interact so weakly. As a result, large missing energy is a very interesting signature. The MET significance provides a measure, in every collision, about whether the observed missing energy is real, or is commensurate with arising from the finite measurement capabilities of the detector. It therefore can play a significant role in suppressing backgrounds to physics signatures of interest.
I also lead LEPP’s software group, which focuses on design and support of the data analysis infrastructure that will enable physicists to analyze the 2 Petabytes of data expected yearly. In addition to our CMS activities, we are collaborating with computer scientists at the University of Utah on projects that can utilize and track data and scientific provenance information to allow better capture and review of the scientific process.
Recent graduates: Richard Gray, Nadia Adam, Matt Shepherd, Tom Meyer, Veronique Boisvert