Professor Richard L. Imlay
imlay@phepds.dnet.nasa.govThe high energy physics group consists of three experimental physicists, Professors Imlay, Metcalf, and McNeil; two theoreticians, Professors Chan and Haymaker; several postdoctoral associates; and a number of technicians, graduate students, and undergraduate student workers.
The experimental group has concentrated on colliding beam physics and neutrino physics. Presently, one major project is the ZEUS experiment, which will operate at the HERA electron proton collider in Germany. The group is also involved in the SSC and are members of the SDC and GEM collaboration.
On the theoretical side, work is in progress to construct dynamical models for quark systems and to apply them to the phenomenology of elementary particles. Further, the underlying symmetries are being investigated to better understand the symmetry breaking that gives rise to observed phenomena. Gauge theories, quantum chromo-dynamics (QCD), effective action expansions, and lattice gauge theories are all under investigation.
Experimental High Energy Physics
Professor Richard L. Imlay
Ph.D., 1968, Princeton University (experimental high energy)
Selected Publications
* "Measurement of the K+e2 Branching Ratio," with D.R. Bowen, A.K. Mann, W.K. McFarlane, A.D. Franklin, E.B. Hughes, G.K. O'Neill, and D.H. Reading, Phys. Rev. 154, 1314 (1974)
* "Obersvations of Muonless Neutrino-Induced Inelastic Interactions," A. Benvenuti et al., Phys. Rev. Lett. 32, 800 (1974)
* "Observation of P-Wave bb Bound States," K. Han et. al., Phys. Rev. Lett. 49, 1612 (1982)
* "Measurements of R and a Search for Heavy Quark Production in e+e- Annihilation at ????s = 50 and 52 GeV," H. Sagawa et. al., Phys. Rev. Lett. 60, 93 (1988)
Assistant Professor Roger McNeil
Ph.D., 1986, University of California, Davis (experimental high energy)
Selected Publications
* "Search for Isolated Leptons in Low Thrust
Annihilation Events at
=50
and 52 GeV, S. Igarashi, et. al.,(AMY collaboration), Phys. Rev.
Let.
60, 2359
* "Measurement of R and a Search for Heavy Quark Production in
Annihilation Events at
=50
and 52 GeV, S. Igarashi, et. al.,(AMY collaboration), Phys. Rev.
Let.
60, 93 (1988)
* "Recent Results from AMY at TRISTAN," R.R. McNeil et al., (AMY Colloaboration), Contributed paper to the XV SLAC Summer Institue of Particle Physics, (1987)
* "Measurement of the Photon Structure Function
in the Region 0.2
,"
H. Aihara, et al ., (TPC/Two-Gamma Collaboration), Zeitchrift
Fur
Physik C, Particles and Fields 34, 1 (1987)
* "Observation of Scaling of the Photon Structure Function
at low
,"
H. Aihara, et al ., (TPC/Two-Gamma Collaboration), Phys. Rev.
Lett. 58,97 (1987)
* "Measurement of
forward -backward charge asymmetry between
=52
and 57 GeV," H. Sagawa et al (AMY Collaboration,) Phys. Rev.
Lett.63, 2341 (1989)
* "Measurements of R for
annibilations at the KEK Collider TRISTAN," T. Kuimta et at
(AMY
Collaboration), Phys. Rev. D42, 1339 (1990)
Professor William J. Metcalf 
Ph.D., 1974, California Institute of Technology (experimental high energy) Selected Publications
* "A Phenomenological Analysis of Pion Photoproduction," W.J. Metcalf and R.L. Walker, Nucl. Phys. B76, 253 (1974)
* "Muon Pair Production in 16 and 22 GeV
Cu Collisions,"J. Alspector et. al., Phys. Lett. B81, 397 (1979)
* "Observation of Three Upsilon State," D. Andrews et. al., Phys. Rev. Lett. 44, 1108 (1980)
* "Measurements of R and a Search for Heavy Quark Production
in
Annihilation at
=50
and 52 GeV," H. Sagawa et. al., Phys. Rev. Lett. 60, 93 (1988)
* "Limits on
Oscillations," L.S.Durkin et. al., Phys. Rev. Lett. 61, 1811
(1988)
The experimental high energy program at LSU started in 1979. In our first experiment we studied electron-positron collisions at the Cornell Electron Storage Ring (CESR). The experiment provided important information on the properties of the b quark by studying the upsilon resonances which are 3S bound states of a b quark and an anti b quark.
We also were involved in an electron-positron experiment in Japan at the TRISTAN storage ring. TRISTAN operated in a previously unexplored energy region and thus was an exciting place to search for possible new particles of phenomena. Now our major project is the ZEUS experiment in Germany. ZEUS is studying electron proton collisions at the new HERA facility. This will permit study of deep inelastic scattering in a totally unexplored region.
Professors Imlay and Metcalf are also members of the SDC (Solenoid Detector Collaboration), which will be a major SSC experiment. Dr. McNeil is working on GEM, the other big SSC detector. He is heavily involved in the study of backgrounds for muon detection. We are participating in several SSC detector research projects.
Professors Imlay and Metcalf are now completing analysis of a neutrino oscillation experiment at Los Alamos. Observation of oscillations of one type of neutrino into another would imply that neutrinos have non-zero mass. There is great theoretical interest in such measurements. Recently, we joined a new neutrino experiment, LSND, at Los Alamos.
Professor Lai-Him Chan 
Ph.D., 1966, Harvard University (particle and quantum field theory)
The emphasis of theoretical particle physics has been centered on higher energy and short distances where the dynamics of particles and fields is more fundamental. However, particle phenomenology as observed in laboratories occurs at low energy. In many cases there is no first-principle method of calculation to relate theories directly to experimental observations. Therefore, it is vitally important to develop theoretical tools and conjectures which serve as intermediate stepping stones for the construction of an effective theory that would eventually lead to the ultimate understanding of particle physics at the fundamental level. We have been working on various aspects of these problems.
On the phenomenological side, by a careful analysis of the charmonium 3P states, we came to the conclusion that the long- range quarkonium confinement potential must be predominantly a Lorentz scalar rather than a Lorentz vector as expected by a Coulomb-like potential. This conjecture, now known as the scalar confinement, has been subsequently strengthened by new experimental evidence from the beauty quarkonium 3P states and confirmed theoretically by lattice gauge calculations.
Using the basic property of QCD that hadron dynamics is flavor independent, we have devised a mass interpolation method which can be used to make model independent predictions on hadron isospin splittings. This calculation has been successfully applied to ordinary SU(3) and the predictions on the isospin splitting of the charmed and b mesons have been verified by recent experiments.
On the theoretical side, much progress and speculation in fundamental interactions in recent years have been based on a hierarchy of levels of effective dynamics at different energy scales. We have formulated a new method for the Derivative Expansion series to express nonlocal quantum corrections of quantum field theory in the presence of background fields as an infinite series of local expressions. This technique has been a very useful tool to calculate effective Lagrangians or to extract low-energy and long wave-length physics from a more fundamental theory. Applications include Skyrmion physics, the strongly interacting Higgs sector of the unified electroweak theory, nonlinear and super-nonlinear [[sigma]] models, supergravity, superstrings, Berry's phase, and anomalies. However, it cannot be used to calculate some interesting physical quantities which require the validity of the series everywhere. To circumvent this difficulty, we have developed a method for the analytic continuation of the derivative expansion series. This method has been applied successfully to calculate the quantum corrections of soliton mass in various models including those models which have no analytical solution.
Selected Publications
* "The Spin Structure of the Effective Quark Hamiltonian and the Hyperfine Splittings of Charmonium," L.-H. Chan, Phys. Lett. 71B, 422 (1977)
* "Hadron Electromagnetic Mass Differences and a Prediction of
,"
L.-H. Chan, Phys. Lett. 51, 253 (1983)
* "Effective-Action Expansion in Perturbation Theory," L.-H. Chan, Phys. Rev. Lett. 56, 404 (1985)
* "Brayons as Solitons in the Effective Lagrangian of Spontaneously Broken Chiral Symmetry," Phys. Rev. Lett. 55, 21 (1985)
* "Derivative Expansion for the One-Loop Effective Actions with Internal Symmetry," L.-H. Chan, Phys. Rev. Lett. 57, 1199 (1986)
* "Effective Lagrangians from Chiral Quark Dynamics," L.-H. Chan,Chiral Soliton, Chapter 2, edited by K.F. Liu, World Scientific, Singapore, 1987
* "Improvement of the Derivative Expansion," L.-H. Chan, Phys. Rev. D38, 3939 (1988)
Professor Richard Haymaker 
Ph.D., 1967, University of California, Berkeley (high energy theory)
Our research is in theoretical high energy physics. Our interests lean toward dynamical questions such as the structure and interactions of strongly interacting particles, symmetry breaking and phase transitions in gauge theories.
One topic of interest is dynamical chiral symmetry breaking. That is to understand the essential physics governing the way QCD realizes broken chiral symmetry. Although lattice gauge theory simulations demonstrate conclusively that this symmetry is broken by the vacuum, it is the continuum Schwinger-Dyson equations which suggest a simple underlying principle that is responsible. We would like to find appropriate operators in lattice gauge theory to investigate the underlying mechanism.
A second major topic of interest is confinement. We have done lattice simulations mapping out the flux lines surrounding quarks and antiquarks. We have been able to determine the detailed profile of the energy and action distributions and were the first to be able to check the Michael sum rules. Recently we have been the first to see a Abrikosov vortex between static quarks. We measured the curl of the monopole current and were able to determine the Ginzburg-Landau coherence length and London penetration depth for an SU(2) pure gauge theory with static quarks. We found that the dual superconductor is on the borderline between Type I and Type II.
Selected Publications
* "Bag Confinement Chiral Breaking Effect on a Goldstone Pion," Phys. Lett. 100B, 276 (1981) (with T. Goldman)
* "Supersymmetry in Quantum Mechanics," (with A.R.P. Rau), Am. J. Phys. 54, 928 (1986)
* "On the Space Structure of Confining Strings," (with J. Wosiek), Phys. Tev. Tapid Communications D36, 3297 (1987)
* "Color Flux Distribution on the Lattice," (with J. Wosiek), Acta Physica Polonica B21, 403, 1990
* "Distribution of the Color Fields Around Static Quarks" Lattice Sum Rules," (with J. Wosiek), Phys. Rev. D43, 2676 (1991)
* "Variational Methods for Composite Operators," Reviste Del Nuovo Cimento, to be published 1991