Norman H. Christ

The standard model of particle physics successfully describes a broad range of natural phenomena with no clear inconsistencies. However, there are some areas where the standard model may fall short. The inflationary period in current cosmology implies that the net number of baryons in the universe was created dynamically with baryons favored over anti-baryons because of violations of charge-conjugation/parity (CP) symmetry. While the standard model does break CP symmetry the mechanism appears too weak to explain the observed baryon density. In addition there are a few standard model parameters such as the Higgs mass and theta angle which are unnaturally small, suggesting some additional principle or dynamics at work.

New phenomena, not predicted by the standard model, are pursued by doing experiments at the highest energies where new particles may be produced and detected. Alternatively, we can make high-precision comparisons of lower energy phenomena with the predictions of the standard model. Because of their strong interactions, quarks are easy to produce and combine into a variety of bound states offering many interesting systems where accurate tests of the standard model are possible. Of course, such tests often require that the effects of the strong interactions can be accurately predicted, a possibility that has recently been realized for many cases by the methods of lattice QCD. Lattice QCD is a numerical, first-principles, non-perturbative approach to calculating the properties of systems of quarks, anti-quarks and gluons.

My research uses lattice QCD to make increasingly accurate, standard model predictions for specific phenomena where there is an increased likelihood of finding beyond-the-standard-model (BSM) physics. The "selected papers" tab lists recent papers which present:

• The first calculation of the standard model prediction for the direct CP violating parameter e' in K -> pp decay.
• The first calculation of the connected and disconnected hadronic light-by-light contribution to the anomalous magnetic moment of the muon.
• Development of a method to compute the very small mass difference (~3 x 10^{-15} GeV) between the long- and short-lived neutral K mesons.
• Development of a method to compute the standard model prediction for the long-distance contribution to the indirect CP violating parameter e in K -> pp decay, intended to increase the precision of this prediction to ~1%.
• Development of a method to compute the standard model prediction for the long-distance contribution to the rare kaon decay K -> pnn decay, intended to increase the precision of this prediction to ~1%.

Some of these projects are large-scale calculations making accurate standard model predictions which can be compared with experiment. Others are efforts to develop and perfect new methods that allow previously inaccessible standard model predictions to be made. These activities involve a highly varied combination of first-principles quantum field theory, quantum mechanics and algorithm design. Because many of these projects require very large computer resources, there is a considerable emphasis on high-performance computing, software engineering and the efficient exploitation of advanced computer architectures and the improvement of those architectures.

These research projects are carried out with my Columbia colleague, Prof. Robert Mawhinney and RBRC-Brookhaven-Columbia (RBC) and UKQCD collaborators at the Brookhaven National Laboratory, the University of Connecticut, the RIKEN BNL Research Center, the Universities of Edinburgh and Southampton and Nagoya University.

B.A., Columbia University, 1965

Ph.D., Columbia University, 1966

A current list of publications can be found here: INSPIRE