High Energy Physics

The High Energy Physics group consists of five faculty experimentalists (one emeritus), and three faculty theoreticians, several postdoctoral research fellows, and a number of graduate students.

The goals of the experimental high energy physics group are to search for new physics and to explore the predictions of the Standard Model to unprecedented accuracy. In order to perform this research, we are involved in the DØ experiment at Fermilab, the CLEO experiment at the Cornell Electron Synchrotron Ring (CESR) and the ATLAS experiment at the Large Hadron Collider (LHC) at CERN. DØ and CLEO are located at national research facilities which are currently collecting data, while the ATLAS experiment, located at an international research facility, is scheduled to begin taking data in the year 2005. In addition to these three large research collaborations, we are also performing a search for low mass monopoles at the University of Oklahoma (OU).

The DØ experiment is situated at the Fermilab Tevatron, which produces the highest energy particle collisions in the world. The collisions between the counter-rotating protons and anti-protons allow us to study the strong (QCD) and electroweak interactions through the decays of the produced particles and through their measured angular distributions. Some of the recent results from the DØ experiment include the discovery of the top quark, a precision measurement of the W mass, and gluon radiation interference effects. In addition, numerous searches for new particles, new forces and discrepancies with the Standard model are all been carried out. A new upgrade is now complete which will greatly enhance the detector's ability. This provides an excellent opportunity over the next few years for new physics discoveries at one of the premier detectors in the world.

The primary focus of the CLEO experiment is to measure properties of the b-quark and its interactions with other fundamental particles of the standard model. Both the production and subsequent decay of particles containing a b-quark are studied, providing deeper understanding of the strong interaction, the weak interaction, and the quantum interference between these two forces.

A search for magnetic monopoles is currently being conducted by a small group of collaborators here at OU. Monopoles created in high energy collisions at the Fermilab Tevatron could be trapped in the detector material surrounding the collision point. We have obtained some of that material and are looking for monopoles using a Superconducting Quantum Interference Device (SQUID) detector. e first run has yielded monopole mass limits on the order of 300 GeV, some three times higher than previous limits for direct searches of accelerator produced monopoles.

Besides the direct physics research, we are also involved in state-of-the-art detector development for D0, CLEO and the ATLAS experiment. This program, which uses our own facilities at OU, focuses on advanced silicon micro-strip detectors. The excellent position resolution of silicon allows identification of short lived particles and allows us to measure their properties.

The theoretical group is studying non-perturbative aspects of quantum field theory (QFT) and gauge theories. QFT is the basic framework for the description of particle physics, as well as for many other areas of physics. The calculations required today to solve field theories cannot be done by considering relatively small corrections (perturbations) to non-interacting theories of quarks and gluons, for example. In particular, non-perturbative methods are essential to understand the phenomena of strong interactions. Thus new mathematical methods are required, some of which are being developed in our group. In addition to developing new types of erturbative expansions and approximation methods, as well as tudying new types of quantum field theories, analytical calculations are being applied to a number of important particle physics topics: quantum chromodynamics, quantum electrodynamics, the Casimir effect (vacuum fluctuations) and its applications glueballs, Kaluza-Klein theories, topological field theories, and quantum gravity. In addition, new theoretical work on magnetic monopole production and binding is being carried out.

Another major focus of our theoretical research is phenomenology of electroweak symmetry breaking, supersymmetric grand unification, CP violation, dark matter, cosmology and theories with extra dimensions. We investigate direct and indirect signatures of new physics beyond the Standard Model in present and future experiments. In addition, we are employing particle physics to explain interesting astrophysical and cosmological phenomena as well as applying astrophysical and cosmological observations to test and constrain particle theories.

Brad Abbott
Assistant Professor
B.A. 1989 University of Minnesota, Morris
Ph.D. 1994 Purdue University

My research in experimental particle physics has been primarily in two major areas. Recently I was involved in the BaBar experiment at the Stanford Linear Accelerating Center located near the Stanford campus. I was involved in building and commissioning a state of the art silicon vertex tracker for BaBar. This detector was constructed of double sided 300 micron thick silicon with a custom designed radiation hard readout chip. The silicon detector allows the vertices of short lived particles to be determined very accurately, a necessity for studying CP violation. My primary physics interest is working on B physics in order to better understand CP violation. I have been involved in B-mixing studies which, along with B $\rightarrow$ J/$\Psi$ K_S, provide a measure of the angle $\beta$ for the Unitarity triangle.

I have also worked on many analyses studying Quantum Chromo Dynamics (QCD) at the D0 experiment at Fermi Lab. Fermilab, located near Chicago, is the highest energy accelerator in the world. With such high energy, one can probe very small distance scales to search for new physics. My analyses were designed to look for quark sub-structure and to test the current theoretical understanding of QCD.

The new, recently upgraded D0 detector will allow us the opportunity to further exploit the highest energy accelerator in the world. With a new silicon tracker, D0 will be able to explore B physics at unprecedented energies. The next few years will be very exciting as D0 will provide one of the best opportunities available to discover new physics.

Measurement of Dijet Angular Distributions and Search for Quark Compositeness, B. Abbott et. al, Phys. Rev. Lett. 80, 666 (1998); Fermilab-Pub-97/237-E; [hep-ex/9707016].

The Dijet Mass Spectrum and a Search for Quark Compositeness in $p\bar{p}$ Collisions at $\sqrt{s}$ = 1.8 TeV , B. Abbott et. al, Phys. Rev. Lett. 82, 2457 1999; Fermilab-Pub-98/220-E; [hep-ex/9807014].

The Inclusive Jet Cross Section in $p\bar{p}$ Collisions at $\sqrt{s}$ = 1.8 TeV, B. Abbott et. al, Phys. Rev. Lett. 82, 2451 (1999); Fermilab-Pub-98/207-E; [hep-ex/9807018].

Phillip Gutierrez
Associate Professor
B.S. 1976 University of California-Riverside
Ph.D. 1983 University of California-Riverside

Over past 20 plus years, I have carried out research in experimental high energy physics. The research has taken place at two of the premier high energy physics laboratories in the world, Fermilab near Chicago, and the CERN laboratory near Geneva Switzerland. Currently I am a member of the DØ collaboration, one of two research groups that uses the Fermilab Tevatron, the world's highest energy particle collider. The goal of the research is to study all aspects of proton anti-proton collisions. This includes studying particles that are produced in these collisions, such as the recently discovered top-quark, refining previous measurements to set limits on how well the standard model of particle physics agrees with data. These measurements will ultimately lead to extensions of the standard model, which should help answer such questions as the origin of mass, the asymmetry between matter and anti-matter in the universe, among many others.

At present I am participating in upgrading the current DØ detector, to improve its charge particle detecting capabilities. This includes work with other members of the University of Oklahoma group in developing a silicon vertex detector. I am also participating, along with my current graduate students, in several physics analysis that involve QCD (strong intereactions) and electroweak interactions (search for a charged Higgs boson).

For the future, I will be participating in the Large Hadron Collider at the CERN laboratory. This will extend the research that I am currently carrying out at Fermilab.

B. Abbott$\ldots$ P. Gutierrez$\ldots$ (DØ Collaboration) ``Measurement of the Shape of the Transverse Momentum Distribution of W Bosons Produced in $p\bar{p}$ Collisions at $\sqrt{s}$= 1.8 TeV.'', Physical Review Letters 80, 5498 (1998).

B. Abbott$\ldots$ P. Gutierrez$\ldots$ (DØ Collaboration) ``$Z\gamma$ Production in $p\bar{p}$ Collisions at $\sqrt{s}$=1.8TeV and Limits on Anomalous $ZZ\gamma$ and $Z\gamma\gamma$ Couplings'', Physical Review D 57, 3817 (1998).

B. Abbott$\ldots$ P. Gutierrez$\ldots$ (DØ Collaboration) `` Limits on WWZ and $WW \gamma$ couplings from $p\bar{p}\rightarrow e \nu jjX$ events at $\sqrt s = 1.8$ TeV'', Physical Review Letters 79, 1441 (1997).

S. Abachi$\ldots$ P. Gutierrez$\ldots$ (DØ Collaboration) `` Direct Measurement of the Top Quark Mass'', Physical Review Letters 79, 1197 (1997).

Ronald Kantowski
Professor
B.S. 1962 Texas
Ph.D. 1966 Texas

My current interests are in cosmology and effective actions for certain topological quantum field theories and Kaluza-Klein spaces. I have recently been working on the quantitative effects of mass inhomogeneities on determinations of the cosmological parameters. With collaborators I have found analytic expressions for the Hubble curve for partially filled beam observations in standard cosmology. With collaborators I am also using the background field method to compute effective actions for certain topological quantum field theories and Kaluza-Klein spaces. To ensure gauge independence of our loop expansions, we have found it necessary to use the effective action of Vilkovisky-DeWitt.

R. Kantowski, J.K. Kao, and R. C. Thomas, ``Distance-Redshift in Inhomogeneous FLRW", astro-ph/0002334, to appear in Ap. J. 545, Dec. 10 (2000).

R. C. Thomas and R. Kantowski, ``Age-Redshift Relation for Standard Cosmology", astro-ph/0003463 to appear in Phys. Rev. D 62, Nov. 15 (2000).

H. T. Cho and R. Kantowski, t``Vilkovisky-DeWitt Effective action for Einstein Gravity on Kaluza-Klein Spacetimes $M^4\times S^N$", hep-th/0004082 Phys. Rev. D 62, Nov. 15 (2000).

Chung Kao
Assistant Professor
BS 1980 National Taiwan Normal University
M.S. 1984 the University of Oregon
Ph.D 1990 University of Texas

My research interests are in theoretical high energy physics, astrophysics and cosmology, especially: Electroweak Symmetry Breaking (EWSB), Supersymmetry, Unification of Fundamental Interactions, CP Violation, Dark Matter, and Theories with Extra Dimensions. One of the most important goals of future colliders is to discover the Higgs bosons or to prove their nonexistence. In the Standard Model of electroweak interactions, the Higgs field condenses (disappears into the vacuum), spontaneously breaking the electroweak symmetry and generating masses for the elementary particles. Weak scale supersymmetry is the most compelling extension of the Standard Model to preserve the elementary nature of the Higgs bosons. In most supersymmetric models, the lightest neutralino can be a good cold dark matter candidate if R-parity is conserved. Recently, I have been investigating direct and indirect signatures of new physics in present and future experiments to pursue interesting physics of electroweak symmetry breaking, supersymmetry, CP violation and astrophysics.

``Trilepton Signature of Minimal Supergravity at the Upgraded Tevatron, V. Barger and C. Kao, Phys. Rev. D60, 115015 (1999) [hep-ph/9811489].

``Parity Violating Asymmetries in Top Pair Production at Hadron Colliders," C. Kao and D. Wackeroth, Phys. Rev. D61, 055009 (2000) [hep-ph/9902202].

``Astrophysical Constraints on Large Extra Dimensions," V. Barger, T. Han, C. Kao and R.J. Zhang, Phys. Lett. B461, 34 (1999) [hep-ph/9905474].

``Phenomenology of a Supersymmetric Model with Inverted Scalar Mass Hierarchy," V. Barger, C. Kao and R.J. Zhang, Phys. Lett. B483, 184 (2000) [hep-ph/9911510].

Kimball A. Milton
Professor
B.S. 1967 University of Washington
Ph.D. 1971 Harvard

The interactions that give rise to the structure of atoms, nuclei, and elementary particles are described by quantum gauge field theories. These gauge theories are Abelian in the case of electrodynamics (photons do not interact directly with each other), and are non-Abelian in the case of chromodynamics, the theory of the strong subnuclear force (gluons couple directly with each other). These theories are mostly understood in the weak-coupling regime, where perturbation theory may be applied.

I am primarily interested in developing nonperturbative methods for use in quantum field theories and gauge theories. The programs under active development include the quantum finite-element lattice method, variational perturbation theory, the delta (or logarithmic) expansion applied to symmetry breaking, analytic perturbation theory, and non-Hermitian PT (parity-time-reversal) symmetric theories. Applications are being made to quantum electrodynamics and quantum chromodynamics. Vacuum energy phenomena (the Casimir effect) are being studied in contexts ranging from cosmological to condensed matter systems (Chern-Simons, sonoluminescence).

New theoretical work on magnetic monopole production and binding is being carried out in connection with an experimental search for monopoles possibly produced at Fermilab.

K. A. Milton, I. L. Solovtsov, O. P. Solovtsova, and V. I. Yasnov, ``Renormalization Scheme and Higher Loop Stability in Hadronic $\tau$ Decay with Analytic Perturbation Theory,'' Eur. Phys. J. C 14, 495-501 (2000).

K. A. Milton, I. L. Solovtsov, and O. P. Solovtsova, ``Timelike and Spacelike QCD Characteristics of the e⁺e^-Annihilation Process,'' Eur. Phys. J. C 13, 497-502 (2000).

Leonard Gamberg and K. A. Milton, ``Dual Quantum Electrodynamics: Dyon-Dyon and Charge-Monopole Scattering in a High-Energy Approximation,'' Phys. Rev. D 61, 075013-1-19 (2000).

K. A. Milton, L. Gamberg, and G. R. Kalbfleisch, ``Direct and Indirect Searches for Low-Mass Magnetic Monopoles,'' in Kurt Haller's Festschrift, Found. Phys. 30, 543-566 (2000).

K. A. Milton and I. L. Solovtsov, ``Can the QCD Effective Charge Be Symmetrical in the Euclidean and Minkowskian Regions?'' Phys. Rev. D 59, 107701-1-2 (1999).

K. A. Milton, A. V. Nesterenko, and V. V. Nesterenko, ``Mode-by-Mode Summation for the Zero Point Electromagnetic Energy of an Infinite Cylinder,'' Phys. Rev. D 59, 105009-1-9 (1999).

I. Brevik, V. N. Marachevsky, and K. A. Milton, ``Identity of the van der Waals Force and the Casimir Effect and the Irrelevance of these Phenomena to Sonoluminescence,'' Phys. Rev. Lett. 82, 3948-3951 (1999).

K. A. Milton, I. L. Solovtsov, and O. P. Solovtsova, ``The Gross-Llewellyn Smith Sum Rule in the Analytic Approach to Perturbative QCD,'' Phys. Rev. D 60, 016001-1-8 (1999).

C. M. Bender and K. A. Milton, ``A Nonunitary Version of Massless Quantum Electrodynamics Possessing a Critical Point,'' J. Phys. A: Math. Gen. 32, L87-L92 (1999).

Patrick Skubic
Professor
B.S. 1969 South Dakota State
Ph.D. 1977 Michigan

My area of research is experimental elementary particle physics. My present interest in this field is in experiments which produce particles containing the heavy ``bottom'' or ``beauty'' quark (``bottom-flavored'' particles). I also have a strong interest in the development of semiconductor detectors for use in high-energy physics experiments, and I am currently involved in several major efforts in the continued development of these detectors.

I am currently involved in an electron-positron colliding beam experiment at the Cornell Electron Storage Ring (CESR). This experiment has been collecting data since 1979, and has produced the world's first direct evidence for the existence of ``bottom-flavored'' particles. The experiment uses a large multi-purpose detector called CLEO. It consists of a superconducting solenoid magnet 1 meter in radius surrounded by detector elements which can measure the trajectories of charged and neutral particles. Particles which contain the bottom quark (B mesons) are produced by collisions between electrons and positrons. This process of matter-antimatter annihilation is very useful in producing heavy quark pairs. (Since the ``bottomness'' quantum number is conserved in strong nuclear interactions, the bottom quarks are produced in pairs.) One goal of the experiment is to investigate symmetry (CP) violation by B mesons as a probe of the fundamental nature of the nuclear force. We have recently observed rare decays of the B meson in which such symmetry violations could occur.

I have also worked within the Department's high-energy group on the development of semiconductor pixel detectors for a future experiment called ATLAS. This experiment is under construction at the European particle physics laboratory CERN located in Geneva, Switzerland. It is a multipurpose detector to study collisions between protons. A major goal of ATLAS is to discover the Higgs particle, which is thought to be responsible for the generation of the masses of other particles according to current theory. One possible decay mode of the Higgs particle is to four b quarks so our experience with bottom physics may prove useful in detecting the Higgs. The pixel detectors we are developing will be the detector elements closest to the collision point and will provide the best position measurement for charged particles produced in the collision.

A. Anastassov, $\ldots$ P. Skubic, $\ldots$, ``First Observation of the Decay $B \to J/\Psi\Phi K$'' , Physical Review Letters 84, 1393 (2000).

J.P.Alexander, $\ldots$ P. Skubic, $\ldots$, ``Measurement of $B \to \rho l \nu$ decay and |V_ub| '', Physical Review D 61, 052001 (2000).

Michael Strauss
Assistant Professor
B.S. 1981 Biola University
Ph.D. 1988 University of California, Los Angeles

I am currently a member of the DØ collaboration doing research in Experimental Particle Physics using the Tevatron collider at the Fermi National Accelerator Laboratory. The Tevatron, which produces the highest energy particle collisions in the world, is an excellent instrument for testing the predictions of the Standard Model of elementary particles and fields and to look for experimental deviations from those predictions. My recent research has focused on testing various properties of Quantum Chromodynamics (QCD), particularly the properties of the gluons within the proton.

The Tevatron is entering a new and exciting era with the completion of the Main Injector and significant upgrades to the DØ detector. With a higher luminosity and a higher center-of-mass energy, we have a possibility of discovering new phenomena which may extend or supersede the Standard Model. Studies indicate that answers to fundamental questions about the nature of mass and the asymmetry between matter and antimatter may be discvovered in the near future at high energy physics laboratories. I have also been involved in testing and developing various silicon microstrip detectors used for finding particle tracks in the DØ upgrade. For years, the University of Oklahoma has been a leader in the utilization of silicon devices for high energy physics detectors and we plan on continuing this effort for the ATLAS experiment currently being built for the LHC.

With the DØ upgrade in the near future, and the ATLAS experiment coming on line soon after that, the future potential for the discovery and observation of new and interesting phenomena in the field of elementary particles and fields looks extremely promising.

B. Abbott,$\ldots$M. Strauss,$\ldots$(DØ Collaboration) ``The Isolated Photon Cross Section in $p\overline{p}$ Collisions at $\sqrt s = 1.8$ TeV'', Physical Review Letters 84, 2786 (2000).

B. Abbott,$\ldots$M. Strauss,$\ldots$(DØ Collaboration) ``The Inclusive Jet Cross Section in $\overline{p}p$ Collisions at $\sqrt s = 1.8$ TeV'', Physical Review Letters 82, 2451 (1999).

B. Abbott,$\ldots$M. Strauss,$\ldots$(DØ Collaboration) ``Search for Charged Higgs Bosons in Decays of Top Quark Pairs,'', Physical Review Letters 82, 4975 (1999).

B. Abbott,$\ldots$M. Strauss,$\ldots$(DØ Collaboration) ``Direct Measurement of the Top Quark Mass at DØ ,'' DØ Collaboration'', Physical Review D58, 52001 (1998).