This is a proposed program of studies that may eventually give new insight into the origin of the matter dominance of the universe and is likely to contribute to our understanding of the origin of mass. The impact of the proposed research program reaches a broad scope within elementary particle physics. The proposed work on active pixel detector technology has application to instrumentation used at synchrotron light sources to study materials and biological systems. The proposed work on distributed databases has strong overlap with work being done by Johnd Hopkins colleagues for several large astronomy projects. Expertise in grid computing is being used to facilitate biological Molecular Dynamics simulations on the Open Science Grid (OSG) and is paving the way for an expanded presence of the life sciences on the OSG. The proposed research also has an educational component. It provides direct support and training for a number of graduate and undergraduate students. The group are the hosts of a QuarkNet center which has a current membership of 13 Baltimore area high school teachers. This QuarkNet Center has initiated and helped to organize a very successful series of regional Physics Fairs that have brought science to thousands of area residents. Quarknet-aliated teachers and their students have also begun to participate in a series of International Masterclasses that are enriching the educational experiences of high school students from around the world.
This project is an ongoing study of elementary particle physics with the CDF detector at the Fermilab Tevatron and with the CMS detector the CERN Large Hadron Collider (LHC). The Tevatron work is now nearly completed and most of the project activities have transitioned to the LHC. The following paragraphs describe several of the most intellectually meritorious outcomes of the project which is aimed at the discovery of new physical processes from the study hadron collisions. The most interesting of the Tevatron results was the updating of an earlier measurement that has suggested that an anomlous source of CP Violation was at work in the decays of "strange" B mesons. CP is short-hand for the mathematical symmetry that links matter and antimatter. Our basic laws of particle physics largely respect this symmetry which suggests that the early universe should have contained equal amounts of matter and antimatter. We now know that a very subtle and small quantum interference effect can violate CP symmetry. However this effect is so small, that it likely does not explain why we live in a matter-dominated universe. Therefore in recent years, particle physicists have searched for other sources of CP violation. In 2007, several members of this project and their colleagues observed that there appeared to be an anomalously large source of CP violation in the decay of the Bs meson to a pair of particles: the J/psi meson and the phi meson which are composed of charm-anticharm and strange-antistrange quarks, respectively. The follow-up measurement supported by this project concluded that the original observation was likely a statistical fluctuation and that no anomalous source of CP violation was being observed. A second result from the Tevatron work was try out a new technique to measure the production rate of top-antitop quark pairs that was being planned for the LHC. Each top decays into a b-quark and W-boson producing a rich final state that allows one to measure the production, various efficiencies, and several important backgrounds simultaneously. The existing CDF top-quark data was used to produce a new measurement that was 30% better than those produced by older techniques. The new technique was then used to analyze data from the 2010 run of the LHC to perform the best single measurement of the top-antitop cross section (production rate) at the LHC. This is important because many theoretical ideas suggest top quarks can be also be decay products of new heavy particles produced at the LHC. It is important to measure their Standard Model production rate so that we know how many to expect as part of background analyses. A closely related outcome was the development of a new technique to reconstruct very energetic top quarks. The LHC is designed to operate at higher energies and to produce heavier particles than any current accelerator. A very heavy particle that decays into top quarks (and other particles) will produce very energetic top quarks. The decay products of a very energetic particle emerge in the detector as a well-collimated spray of particles: they are close together as they transit the detector. This causes the top quark decay products to look like the ordinary jets of particles that are the manifestations of scattered quarks and gluons from routine LHC collisions. If one does nothing special, events with very heavy and interesting new particles would disappear in a forest of ordinary events. One of the major activities of the project has been to develop new techniques to identify very energetic top quark "jets". Building on the work of some theoretical colleagues at JHU, a new algorithm that decomposes a jet into smaller fragments was developed and deployed. Since the top decay products (b-quarks and W-boson) produce smaller jets within the top jet, they can be separated from ordinary light quark and gluon jets that don't have the smaller jets. This technique can improve the signal-to-noise ratio of an analysis looking for pairs of energetic top quarks by a factor of nearly 1000! The project has also had a number of broader impacts. It has educated and professionally developed three postdoctoral scientists, six graduate students two of whom have earned PhD degrees, and several undergraduates. The group's expertise in gridded computing was used to facilitate biological Molecular Dynamics simulations on the Open Science Grid (OSG) and has paved the way for an expanded presence of the life sciences on the OSG. The project has hosted a QuarkNet center which provides professional development to a group of 25 Baltimore area high school teachers. The QuarkNet Center has initiated and helped to organize a very successful series of regional Physics Fairs. Our group with our Quarknet-affiliated teachers and their students also participate in a series of International Masterclasses that are enriching the educational experiences of high school students from around the world.
