# Theoretical particle physics research

*Professors Gil Paz, Alexey A. Petrov, Nausheen R. Shah*

The major thrust of research pursued by the Wayne State University particle theory group is to study the Standard Model (SM) and its extensions using the interplay between high energy physics theory, experiment, and cosmology. In recent years the group has worked on a variety of problems in the theory and phenomenology of Beyond the SM physics as well as of the strong, electromagnetic, and weak interactions.

The Standard Model, as we understand it, consists of three generations of quarks and leptons, charged under the symmetry groups: SU(3) x SU(2) x U(1) corresponding to the strong, weak and electromagnetic forces. The quanta for these forces are associated with the gluons, the W and Z bosons, and the photon respectively. This model has been thoroughly verified experimentally. In particular, the electroweak sector has been analyzed extensively and for any new physical theory, the theoretical predictions would have to be consistent with these precision electroweak data.

However, even though the SM has been so successful experimentally, there are a lot of unanswered questions: Quantum gravity has yet to be incorporated in a consistent manner; the hierarchy problem: why is the energy scale of the weak force so different from the scale of gravity? With the discovery of the Higgs boson at the LHC, we believe we understand the mechanism responsible for the generation of the fundamental particle masses, however, the dynamics leading to electroweak symmetry breaking are still a mystery.

Apart from these theoretical questions, we get hints that physics beyond the SM must exist from astrophysics. The observed rotation curves of matter in the universe can't be explained with the known matter content. Therefore, an unknown particle is hypothesized to consist of "dark matter."

A partial list of research topics includes particle astrophysics, Higgs precision phenomenology, mediation of supersymmetry breaking, Z' models, applications of effective field theories to problems in Quantum Chromodynamics (QCD), heavy meson decays and precision QED, studies of the properties of heavy hadrons, meson spectroscopy, and physics of CP-violation. The group is also one of the worldwide leaders in the description of weak transitions of charmed hadrons and radiative decays of B mesons. The research program of WSU's particle theory group has significant overlap with the current research interests of Wayne State's experimental particle physics (CMS) and theoretical nuclear physics groups.

These activities are supported by grants from the U.S. National Science Foundation and the Department of Energy.

For a list of publications by members of this group, visit INSPIRE, the High Energy Physics information system: Gil Paz, Alexey A. Petrov, Nausheen R. Shah.