Prof. Robert L Jaffe

Professor Jaffe's research specialty is the physics of elementary particles and quantum field theory, especially the dynamics of quark confinement and the Standard Model. Most recently he has been researching the dynamical effects of the quantum vacuum (Casimir Effects) on micron scales. He has also worked on the quantum theory of tubes, the astrophysics of dense matter and many problems in scattering theory. Jaffe teaches quantum mechanics, field theory, mechanics and electrodynamics at the advanced undergraduate and graduate levels.

Jaffe is best known for his research on the quark substructure of matter. In the early 1970s he and his colleagues at MIT formulated the first consistent description of quark confinement, the "MIT Bag Model." Together with John Ellis of CERN, Jaffe formulated a sum rule which relates polarized lepton scattering to the spin substructure of the nucleon. Tests of this sum rule sparked a renewal of interest in the hadron spin physics. His more recent work in this area (in collaboration with Xiangdong Ji of the University of Maryland) includes the elucidation of the "transversity," a novel quark spin observable accessible in hard scattering experiments. He has been deeply involved in the development of the spin physics program at Brookhaven National Lab. Jaffe also began the systematic study of exotic hadrons in the 1970s. He proposed that the scalar (spinless) mesons should be interpreted as two quark, two antiquark states, an interpretation which has only recently won wide acceptance. He and Kenneth Johnson (at MIT) launched the theory of glueballs—hadrons made entirely of the gluons which mediate confining forces. Together with Edward Farhi (also at MIT), Jaffe first described the properties of strange quark matter and explored its significance in astrophysics.

In the late 1990's Jaffe, Farhi, and collaborators developed analytical and computational tools for the study of quantum vacuum energies—Casimir energies—with applications to problems ranging from micromachinery to beyond the Standard Model. Recently this work has taken a practical turn: Antonello Scardicchio (MIT, now Princeton) and Mehran Kardar (MIT), Jaffe developed powerful practical methods to determine the geometry dependence of Casimir forces as they affect micro-electro-mechancial systems (MEMS). Most recently, in collaboration with Thorsten Emig (CNRS- Saclay), Noah Graham (Middlebury), and Kardar, Jaffe has developed practical methods to compute electromagnetic Casimir forces and torques between compact objects of arbitrary shapes whether perfect conductors or dielectrics. This work promises major advances in the calculation of Casimir forces.

Jaffe continues to work on the physics of quarks and hadrons. In 2003 Jaffe and Frank Wilczek (MIT) reconsidered the importance of di-quark correlations in quantum chromodynamics. In 2005 and 2006 Jaffe and collaborators explored the importance of parity doubling in hadron spectroscopy, and catagorized "ordinary" and "extraordinary" resonances in QCD.