Faculty Members -- R. Brower, R.S. Chivukula, A. Cohen, A. DeRujula, R. Giles, K. Lane, S-Y. Pi, C. Rebbi, E. Simmons
Distinguished Visiting Scientist -- S. Glashow
Research Faculty & Associates -- H. Lee, A. Levi, M. Schmaltz
Graduate Students -- B. Balaji, E. Benedict, G. Bonini, I. Das Gupta, B. Dobrescu, Y. Su
The goal of particle physics is to understand the fundamental constituents of matter and their mutual interactions. Particle theorists attempt to reach this goal in a variety of ways, but they depend on close contact with the results of their experimental colleagues to test theoretical ideas. The "standard model" of particle physics is that the fundamental constituents are quarks, leptons, gauge bosons and the graviton, interacting via the strong, electroweak and gravitational interactions. At Boston University, this picture and its possible extensions are investigated by a wide range of approaches including:
(1) attempts to determine the physical origin of electroweak symmetry and the breaking of quark and lepton flavor symmetries;
(2) numerical simulations of complex physical situations such as Quantum Chromodynamics and critical phenomena in Statistical Mechanics;
(3) the impact of particle physics on cosmology;
(4) the application of mathematics to quantum field theory, especially with the hope of developing a consistent, unified theory of all interactions, including gravity.
Electroweak Symmetry Breaking -- R.S. Chivukula, A. Cohen, K. Lane, E. Simmons
The problems of the breakdown of electroweak and flavor symmetries are among the most pressing facing particle physics today. Electroweak symmetry breaking is manifested by the nonzero masses of the weak W and Z bosons. To solve the problem of flavor and its symmetry breaking, one must understand the number of quarks and leptons and why they have such a peculiar pattern of masses. Today, there is no generally accepted theory of these phenomena nor any experimental evidence for their dynamical basis. Several theoretical approaches to electroweak and flavor symmetry breaking are being actively investigated at Boston University. All of them require new particles and interactions near the electroweak energy scale of one trillion electron volts. Our research is aimed at formulating consistent theoretical models of these scenarios and at working out their experimental consequences.
The Big Bang, Dark Matter, and Cosmology -- R.S. Chivukula, A. Cohen, S.-Y. Pi
Many of the questions of current theoretical interest are beyond the energy reach of existing accelerators. However, extremely high energies were once realized in the largest natural particle accelerator, the Big Bang. Shortly after the Big Bang, the universe was composed of a hot plasma of elementary particles. The nature of this plasma, which depends on the properties of the constituent elementary particles, determined the subsequent evolution of the universe. By observing the universe today, we can obtain information about its state shortly after the Big Bang and obtain information about the interactions of these particles at high energy. There are several aspects of cosmology currently under study at Boston University, including inflation of the early universe, the mechanism for producing the baryon excess, nucleosynthesis, "dark" matter, and the formation of large scale structure in the universe.
Quantum Chromodynamics -- C. Rebbi
A crucial component of the scientific process consists in deriving quantitative predictions from assumed theoretical models. The power of modern computers has added a new dimension to this aspect of research. Today, physicists can use advanced numerical techniques to simulate the behavior of very complex systems and thus solve problems that defy the more traditional methods of mathematical analysis. Scientists in the particle theory group have been applying forefront computational methods to the study of quantum chromodynamics (QCD, the theory of interacting quarks and gluons) and to other particle models. Space-time is approximated by a lattice of points and the fundamental fields, defined over this lattice, are represented by an extremely large collection of numbers stored in the memory of a supercomputer. Calculating at the rate of billions of operations per second, the computer simulates the effects of quantum fluctuations of the fields. From such techniques, one calculates fundamental observables such as particle masses, the temperature at which quarks and gluons become unbound or the surface tension of a nucleating hadron. Students, research staff, and faculty working on these problems avail themselves of the supercomputer resources and support structure of the Center for Computational Science (see below). While doing research in the fascinating and challenging field of subatomic particles, students also acquire invaluable expertise in the use of the most modern and powerful supercomputer technologies.
The Center for Computational Science -- R. Brower, R. Giles, C. Rebbi
Boston University has a strong tradition of support for advanced scientific computing. It was one of the first universities to install a massively-parallel supercomputer when it acquired the CM-2 Connection Machine in 1988, which was made available as a university-wide resource for research and education. In 1992, the CM-2 was replace with a 64-processor CM-5, which was then again at the forefront of supercomputer technology. With the assistance of a major grant form the National Science Foundation, the university is now phasing in its next-generation supercomputer facility. The first phase equipment, which arrived in early July, 1995, consists of a 38-node POWER CHALLENGE array from Silicon Graphics Inc., with peak performance of 13 Gflops. Within the next two years, the university will install, in two stages, the second phase equipment, which will consist of a next-generation SGI with an ultimate peak performance of at least 65 Gflops. At completion, the new facility will have brought about a tenfold increase of the computational power formerly provided by the CM-5.
The Center for Computational Science brings together researchers and students
from a wide variety of field and provides support for computationally-intensive
applications. Scientists associated with the Center are active in very many
computational projects, spanning areas as diverse as particle physics, remote
sensing, fluid dynamics and bioengineering. The multidisciplinary aspects
of advanced scientific computing are especially emphasizes. In 1993, the
Center, in coordination with the departments of Chemistry, Computer Science,
Electrical, Computer and Systems Engineering, and Physics was awarded a
grant from the National Science Foundation to introduce a new, interdisciplinary
sequence of courses in parallel computing for undergraduates and a second
grant to develop a high-performance computing laboratory for these courses.
This laboratory of networked, multimedia workstations linked to our high-end
supercomputers provides a unique opportunity for undergraduate and graduate
students to develop expertise in leading-edge technologies.
Students, research staff and faculty from the Physics Department are engaged
in a wide variety of computational research projects in theoretical an experimental
particle physics, condensed-matter physics, statistical mechanics, biophysics
and polymer physics. Students that would like to specialize in computational
physics will find excellent opportunities for interesting and stimulating
research within the Center for Computational Science.