This award funds the research activities of Senior Research Scientist George T. Fleming of Yale University, who is co-spokesperson of the Lattice Strong Dynamics (LSD) collaboration. In 2012, physicists from around the world working on the Large Hadron Collider (LHC) announced the discovery of the long-sought Higgs boson, for which the Nobel prize was awarded the following year. As theoretical particle physicists applaud the discovery, they are also quite confused that no new physics beyond the Standard Model (BSM) was discovered along with the Higgs boson. So, it remains a mystery how the Higgs boson avoids the effects of quantum gravity, which would make it much heavier than has been observed. This mystery could be solved if the Higgs boson turned out to be a composite particle in much the same way as protons and neutrons are composites made of quarks and gluons, rendering it immune to the effects of quantum gravity. There has been no direct evidence that such a composite scalar could exist until recently, when the LatKMI group of the Kobayashi-Maskawa Institute in Nagoya, Japan announced the first calculation of a light composite scalar consistent with the Higgs boson. As leader of the LSD collaboration, Dr. Fleming is working to confirm this scenario by repeating and improving upon the calculation of the LatKMI group. Lattice gauge theory (LGT) calculations of many physical observables essentially involve extracting exponentially decaying signals from noisy time series data generated in Monte Carlo simulations. Many other scientific fields, e.g. nuclear magnetic resonance (NMR) spectroscopy, signals processing, share common challenges in data analysis of exponential time series. Undergraduates often choose this research topic because the skills they learn remain useful even if they don't continue to work on LGT later in their careers.
The LSD collaboration has begun generation of SU(3) gauge configuration ensembles with eight flavors of Dirac fermions in the fundamental representation. This strongly-coupled gauge theory has long been proposed as a candidate for Walking Technicolor. The calculation of the LatKMI group has shown that the theory contains a surprisingly light scalar particle consistent with the Higgs boson. Calculating the mass of this scalar particle is particularly challenging so the LatKMI result has rather large statistical errors. The LSD collaboration, with access to the Vulcan BG/Q supercomputer at Lawrence Livermore National Lab (LLNL), can improve upon the existing calculation with improved statistics, larger physical volumes and smaller quark masses. This improved calculation will be a stringent test of whether this light scalar particle can be a viable composite Higgs candidate.
