Experimental High Energy Particle Physics

Group Overview

High energy physics is concerned with the fundamental interactions of elementary particles, among them the six quarks and six leptons of the Standard Model. Many of our activities focus on the physics of heavy quarks, especially the bottom (b) quark and the charm (c) quark. These are "cousins" of the up and down quarks that bind to form the familiar proton and neutron. Several mysteries in the very successful Standard Model of particle physics involve the weak interaction, which can be studied via the decays of these heavy quarks. Among these mysteries are the matter-antimatter asymmetry of the universe and the origin of mass.

Our faculty currently work on the energy frontier with the CMS experiment at the LHC (near Geneva, Switzerland) and the CDF experiment at Fermilab (near Chicago, Illinois), and on precision charm physics with the BESIII experiment at IHEP (Beijing, China). We are active in all aspects of our collaborations, playing significant roles in detector construction, software infrastructure, physics analysis, and collaboration management. Recently, members of the CMU HEP group have been involved in the first observation of Bs meson oscillations, precision measurements of weak charm decays, and construction of the CMS experiment at the LHC.

Our HEP group also has ties to many other groups in our Department. Our High Energy Theory group has been very active in weak-interaction topics relevant to heavy-quark physics. Our collaborations have made many contributions to hadron spectroscopy (finding new bound states of quarks), which overlap with some of the efforts in our Medium Energy Experiment group. Furthermore, lattice QCD and other techniques of the Medium Energy Theory group are important to both weak physics and hadronic spectroscopy. Finally, the energy-frontier work at the LHC has the potential to discover specific new particles that may form the dark matter of the universe, a major interest of the McWilliams Center for Cosmology.

Member Research Thrusts

Briere studies heavy quarks produced at electron-positron colliders. Current efforts include work with the new BESIII detector in Beijing, and continued analysis of CLEO-c data; both focus on the charm quark. The main physics topic being pursued is weak decay "flavor physics", studied with D meson pairs containing one charm quark each. His other contributions to experiments include drift-chamber calibration and simulation, analysis tools, and various management roles.

Ferguson's research interests are in experimental high-energy particle physics and, in particular, the use of electron-positron and proton-proton colliding beam accelerators. A member of the Compact Muon Solenoid (CMS) collaboration, which has constructed a massive detector for the Large Hadron Collider (LHC). The LHC is a 14 TeV proton-proton colliding beam accelerator, situated at the European accelerator center, CERN, in Geneva, Switzerland. With the detector, we hope to discover not only the Higgs boson of the Standard Model, but entirely new families of particles predicted by various theories.

Paulini studies questions connecting particle physics phenomena to issues relevant to cosmology. One of those questions concerns the fact that our visible universe exhibits a predominance of matter over antimatter. A process in particle physics called CP violation is considered relevant for breaking the symmetry between matter and anti-matter particles. Paulini studies CP violation in mesons containing b-quarks with the CDF experiment at Fermilab. Another question concerns the nature of dark matter that makes up about one quarter of the content of the universe. Paulini searches for the production of dark matter particles with the CMS experiment at CERN.

Russ's research centers on heavy quark physics at CDF and CMS, as well as particle astrophysics studies of ultra-high energy neutrino sources, e.g., Active Galactic Nuclei. At CDF Russ is involve in B-physics and Quarkonium studies. These lead naturally into similar physics studies in the early running at CMS. Later Russ will work on Exotic searches for New Physics, using muons as probes. The neutrino work is now at the prototype stage and will develop over the next several years.

Vogel's research interests are in experimental high-energy physics at colliding-beam accelerators. On the CLEO experiment at the Cornell electron-positron collider, CESR, Vogel's interest is in the study of quarkonium (charmonium and bottomonium) which probes quark-antiquark potential models and QCD. Vogel is also involved in the CMS experiment at the LHC at CERN. There, the study of heavy quarkonium serves both as a tool for monitoring and optimizing detector performance and as a probe of hadronic physics processes in proton-proton collisions in the multi-TeV energy range.