Particle Physics
The High Energy Physics (HEP) group consists of four faculty members (Abbott, Guttierrez, Skubic, Strauss, and Stupak) who perform experimental research and five faculty members (Baer, Kantowski, Kao, Milton and Sinha) who perform theoretical research, as well as several postdoctoral research fellows, and other personnel supporting research including a research scientist, an IT specialist, and an engineer. 
In 2020, the group hosted the International Particle Physics and Cosmology Conference (PPC).
OU HEP Experimental group.
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 (near Chicago) and the ATLAS experiment at the Large Hadron Collider (LHC) at CERN. While DØ continues to analyze data, the ATLAS detector, one of the premiere instruments for scientific discovery, is currently taking and analyzing data from the LHC. The LHC and ATLAS are expected to run for many years and should offer insights into the structure and origin of the universe for decades to come.
The DØ experiment analyzes data taken at the Fermilab Tevatron which was produced by the world’s highest energy proton antiproton collisions. This data is being used 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. For the next few years new physics discoveries will continue to emerge from data taken by DØ. The LHC is the highest energy proton-proton collider ever constructed. It is currently operating at a collision energy of 8 TeV and will eventually approach 14 TeV. These energetic collisions are probing some of the most fundamental questions in the universe. Our group is involved in measuring the properties of the newly discovered Higgs boson. Other questions regarding the origin of mass, the nature of dark matter in the universe, and the reason for the abundance of matter over anti-matter may be answered at the LHC. We will look for more fundamental structure within the quarks and leptons that make up our universe and probe fundamental questions about supersymmetry, string theory, and extra dimensions. Though definitive answers to these questions are far from certain, the energy and collision rate of the LHC should make it one of the most exciting scientific tools ever built by humans. Besides the direct physics research, we have also been involved in state-of-the-art detector development for the DØ and the ATLAS experiment. This program, which often 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.
OU HEP Theory group
The OU HEP Theory group explores beyond-Standard Model physics, early Universe cosmology, and string phenomenology. Specific topics include: the physics of string moduli and axion-like-particles, notions of supersymmetric naturalness coming from the string landscape, phase transitions in the early Universe and their signals in gravitational wave detectors, and collider phenomenology of the Higgs sector. We also study models of dark matter.
The theoretical group is studying perturbative and nonperturbative aspects of quantum field theory (QFT) and gauge theories. A major focus of our HEP theory group is at the theory/experiment interface, called phenomenology. Theorists are investigating QCD, the electroweak theory, and prospects for the detection of Higgs bosons at colliding beam machines such as the LHC and the future International Linear Collider. We are also active in exploring physics ideas that go beyond the Standard Model, such as grand unified theories, supersymmetry, string theory and the possibility of extra spacetime dimensions. Theorists in our group have been pioneers in calculating production and decay rates for new superparticle matter states at the LHC and other colliders. We also examine ideas at the particle physics/cosmology interface, especially issues such as dark matter candidate particles and their production in the early universe, and dark matter detection at underground or space-based facilities. 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 perturbative expansions and approximation methods, as well as studying new types of quantum field theories, analytical calculations are being applied to a number of important particle physics topics: quantum chromodynamics, quantum electrodynamics, magnetic monopole physics, and the Casimir effect (vacuum fluctuations).
Another major area of focus of the theory group is early Universe cosmology and the physics of dark matter. Members study the effect of string moduli and phase transitions on the early thermal history of the Universe. Members also study various dark matter candidates, including axions and WIMPs, and strategies for their detection.
Andre Lessa One of our recent graduates, Andre Lessa, won the APS Sakurai prize for outstanding dissertation in theoretical particle physics, see the APS article.
Research Areas
Faculty
Research Highlight:
In a recent study led by graduate student Nickalas Reynolds, a team of scientists peered deep into the Perseus molecular cloud with the Atacama Large Millimeter/submillimeter Array (ALMA) to produce these images and study IRS3B and A. Reynolds and collaborators determine from their observations that the disk of IRS3B is gravitationally unstable at radii of 200–500 au, and its fragmentation may have recently produced the third protostar in IRS3B (visible as the outer bright spot in the circum-triple disk), which lies at 230 au.
Research Highlight: OU-Apache Point Observatory Partnership
The University of Oklahoma has signed a 3-year lease agreement with the Astrophysical Research Consortium in Sunspot, NM (see the press release), giving its undergraduate students, graduate students, postdocs, and faculty access to research-grade 3.5m and 0.5m telescopes at the Apache Point Observatory. After being trained to use these facilities on-site in NM, OU astronomers will operate these telescopes from their offices in Norman. The agreement will help elevate OU’s astrophysics research profile and provide invaluable educational training to OU students.
Research Highlight: Munshi Galaxy Group
Prof. Munshi, in collaboration with scientists at Rutgers, Grinnell and UW ran two new computer simulations of Milky Way-mass galaxies and their surroundings. They are the highest resolution simulations ever published of Milky Way-type galaxies. They are cosmological simulations, meaning that they start soon after the Big Bang and model the evolution of galaxies over the entire age of the Universe (almost 14 billion years). The high resolution allows us to achieve something that no one else has: we are able to model some of the lowest-mass of the Milky Way’s neighboring (“satellite”) galaxies. In recent years, “ultra-faint” satellites of the Milky Way have been discovered as digital sky surveys come online that can probe to fainter depths than ever before. While our own Milky Way contains about 100 billion stars and is thousands of lightyears across, ultra-faint galaxies contain a million times fewer stars, with less than 100 thousand stars (even as low as a few hundred stars), and are substantially smaller, spanning tens of lightyears. Our simulations allow us to begin to model these ultra-faint satellites for the first time around a cosmological simulation of a Milky Way, meaning they provide some of the first predictions for what future surveys will discover. Research in the Munshi Galaxy Group includes utilizing these simulations, dubbed the "DC Justice League" and extremely high resolution simulations of isolated dwarf galaxies (the "MARVEL-ous Dwarfs") to study galaxy formation and constrain the nature of dark matter using galaxies.
These simulations are only achievable by using powerful supercomputers with highly optimized code. Press release here. For a visualization of a simulation, click here.
Research Highlight: Star Chemistry
The Ring Nebula was formed when a Sun-like star nearing the end of its life ejected part of its atmosphere into the interstellar medium. The nebular gas itself is heated by the UV continuum from the remnant of the original star visible at the center of the Ring. Also shown is a slitless spectrum of the Ring, where an image of the nebula appears at wavelengths of bright nebular emission. Planetary nebulae are useful in Prof. Henry’s research in determining properties of the interstellar medium as well as for studying the evolution of stars like the Sun. Credits: Image, Hubble Heritage Team (NASA); Spectrum: Julie Skinner (former OU Astronomy undergraduate), using the 2.1 meter telescope at KPNO.
Research Highlight: Active Galactic Nuclei
Active Galactic Nuclei (AGN) such as the one imaged here by the Hubble Space Telescope, are the most luminous, persistently emitting individual objects in the Universe. They can be seen at the largest distances, and provide a probe of the early Universe after structure formation. Used as a background light, absorption lines in their spectra trace nonluminous matter. They are powered by accretion onto black holes, and are key for understanding black hole demographics and the black hole mass function. Prof. Leighly works to understand how the primary physical parameters for black hole accretion, the black hole mass and accretion rate, manifest themselves in the broad band continuum and line emission from AGN.
Research Highlight: That Vacuum Is Really Something!
One effort of Prof. Milton and his research group is to understand the nature of the quantum vacuum, which is important in explaining dark energy as well having applications to nanotechnology. The images of cylindrical wedges may be relevant to understanding the quantum nature of cosmic strings, while the corrugated surfaces represent an idea for building nano-gears, in which the mechanical bodies never touch each other, but in which forces and torques are transmitted by quantum vacuum energy.
Research Highlight: Finding the Big W
The image shows a candidate W boson production event at the Atlas detector at Large Hadron Collider (LHC) at the CERN international research facility. The LHC is a proton-proton collider operating at center-of-mass energy 7 trillion electron volts. In this event the W boson has decayed to an electron plus a neutrino in the final state. The OU High Energy Physics group is heavily involved with the LHC Atlas detector.
Research Highlight: Abraham Research Group
Our research group investigates ultracold atoms and molecules. Using lasers to cool rubidium atoms to less than 1 thousandth of a degree above absolute zero, we study their behavior. With lasers and precisely controlled magnetic fields we induce resonant collisions to form new molecules, which helps us better understand molecular interactions. We use diffractive optics to create unique atom trapping geometries, including toroidal and ring-shaped traps. The ultracold atoms are used as a medium for non-linear optics experiments with these novel laser fields that may impact optical computing. Contact Dr. Eric Abraham for more information.
Research Highlight: Testing the Standard Model in a Single Molecule
Symmetry dictates that states of an atom or molecule with total angular momentum M?0 along the axis of an electric field will exhibit a two-fold degeneracy between states differing only in the sign of M. A time-reversal asymmetry could break this degeneracy. Almost every alternative to the Standard Model, (most notably Super Symmetric Theories), indicate that time-reversal asymmetry should lead to an observable energy difference between these otherwise degenerate ±M states. Prof. John Moore-Furneaux is searching for the signal of this time reversal asymmetry: a non-zero electric dipole moment of the electron. High precision measurements of PbF may reveal what billion dollar accelerators have not: evidence of physics beyond the Standard Model.
Research Highlight: Blume Group
Our group is looking at a wide range of static and dynamic few-body phenomena. We are interested, e.g., in understanding what it takes to bind two, three, or four particles together. How does the single-particle dispersion come into this? And what are the differences in terms of critical binding between short- and long-range interactions? Knowing how two, three, or four particles behave, can we predict what is happening at the many-body level? Please do not hesitate to contact Professor Doerte Blume for more information.
Research Highlight: Watson Group
My group is engaged in the study of large many-body systems under quantum confinement, such as Bose-Einstein condensates and ultra-cold systems of Fermi gases. We are developing a method which minimizes numerical effort by using powerful group theoretic as well as graphical techniques. Our approach can handle strongly correlated systems of fermions and can describe their macroscopic collective motions. Fermion systems are important in many fields of physics provide the underpinnings for many technological applications. Our goal is to bridge the gap between a microscopic quantum description and the macroscopic properties of large N-particle correlated systems.
Research Highlight: Shaffer Group
Our research group studies atom based sensing exotic states of matter and various topics involving quantum engineering. All of our projects currently involve Rydberg atoms. Rydberg atoms are highly excited atoms that possess exaggerated properties that make them well suited for applications that require controllable long range interactions. We have projects investigating novel long range molecules formed by Rydberg atoms such as macrodimers and trilobite molecules, studying Rydberg atoms for quantum optics and using Rydberg atoms for traceable sensing of electric fields. Please do not hesitate to contact Professor James Shaffer for more information.
Research Highlight: Marino Group
Our research is in the field of experimental quantum optics, with particular emphasis on quantum information and quantum metrology. Quantum optics studies the quantum properties of light and their applications. Our research is based on the generation and control of entangled photons with atomic systems. The projects we are currently working on involve quantum engineering of our source to tailor the properties of the entangled photons and interfacing the entangled photons with devices, such as plasmonic sensors, to increase their sensitivity. Please do not hesitate to contact Professor Alberto Marino for more information.
Research Highlight: Schwettmann Group
Our group does research in the field of experimental ultracold atomic gases. We focus on cold collisions in sodium spinor Bose-Einstein condensates. At temperatures close to absolute zero, attainable with the methods of laser cooling and trapping and evaporative cooling, coherent collisional spin dynamics become observable in the gas. The dynamics are due to spin-exchange collisions and can be controlled with external fields. They present an opportunity to create exotic, entangled spin states useful for atom interferometry and will allow us to do experiments on quantum optics with matter waves. Currently we are in the early stages of setting up a new lab. Please do not hesitate to contact Professor Arne Schwettmann for more information.
Research Highlight: Good vibrations
On the top is a model of a carbon nanotube (CNT) to which alkane chains have been attached. Below are “bad” and “good” normal modes for conduction of heat through the system, as calculated by Abdellah Ait-Moussa, a student working with Prof. Mullen. A “bad” mode only couples to atoms in the CNT; a good one couples to the side chains as well as the CNT, so that the vibration and the energy it carries goes through the whole system. The goal of the research is to optimize the side chains to maximize the flow of heat. Improving heat conduction into CNT’s may lead to plastics that conduct heat as well as metals.
Research Highlight: Topology driven by interactions
Nodal-line semimetals are a class of materials where the Fermi surface has the form of closed loops with low energy Dirac fermions as quasiparticles. Interactions can spontaneously break symmetries and open an energy gap around those lines. When the gap has nodes around the nodal line, as in the 3D quantum anomalous Hall effect, which is topological, the nodes form Weyl points connected by Fermi arcs, as shown above. Those fermi arcs describe topologically protected surface states, with a non-universal Hall conductivity. Prof. Bruno Uchoa’s group is interested in the interplay of strong many-body interactions and novel macroscopic manifestations of quantum phenomena.
Research Highlight: Bumm Group
The scanning tunneling microscope (STM) provides an atomic view of surfaces with picometer precision. In recent work, graduate student Mitch Yothers working in the Bumm group has demonstrated analytical tools the group is developing to extract statistical information from STM images. The example above starts with a 25 nm × 25 nm atomically resolved image of graphite which contained 11,372 unit cells (not shown). After removing systematic distortion from the image and identifying the location of each atom in the image, the unit cell images can be averaged to produce the averaged unit cell images (gray scale). The standard deviation of the location of the atoms is shown as 1 σ and 2 σ atomic confidence intervals (ellipses).
