The Physics and Astronomy colloquium is a forum for invited scientists to present modern research in a fashion accessible to those with a background in physics, but who are not experts in the field. Talks are aimed at a graduate level.
The colloquium is held most Thursdays during the Fall and Spring semesters at 3:45 pm in Room 906 (9th floor) of Dale Hall Tower.
If you have questions about our colloquia or wish to be added to the mailing list for Zoom meetings, please contact Mike Strauss at strauss@ou.edu.
If you are looking for a schedule of past colloquim presentations for a particular semester, you can find them in our Colloquium Archive.
Title: "Warped discs as a pathway for planet formation"
Abstract: The last decade of observations of protoplanetary discs have shown a wealth of substructure including rings, gaps and spiral arms. Perhaps most intriguingly these observations also revealed the importance of the 3D structure of discs, where some discs are observed to have orientations that change as a function of radius or may also be broken. These so called 'warped discs' have challenged our understanding of disc evolution, and recent work has shown that these discs form a significant fraction of the disc population. In this talk I will discuss the connection between warped discs and the onset of planet formation, a major open question in planetary science.
Host: Mukremin Kilic
Title: "Ultracompact White Dwarf Binaries in the Era of All-Sky Surveys"
Abstract: Compact binaries (CBs) are short orbital period binaries where the primary component is a stellar remnant. Those where the primary star is a white dwarf are expected to be the most abundant, providing a unique opportunity to explore a plethora of astrophysical phenomena. A relatively rare subclass, the ultracompact white dwarf binaries, which are systems with orbital periods of less than 70 minutes and are He-rich, are particularly intriguing. Despite in the last decades several sophisticated and sensitive telescopes have led to an increase in their detection and study, their number, outbursts and overall behavior challenge traditional models. In this talk, I will describe how using data from current all-sky surveys we are exploiting the transient behavior of these binaries to identify them, characterize them and place constraints on their accretion processes. I will address the importance of including irradiation and mass transfer enhancement. Additionally, I will discuss the implications of recent findings for the detection of such binaries by space-based gravitational wave observatories like LISA and the next generation of all-sky surveys.
Host: Mukremin Kilic
Title: "The Detection and Characterization of Exoplanets Around Low-Mass Stars with TESS"
Abstract: Over the past 30 years, we have discovered more than 5,000 exoplanets through a variety of detection methods. Since 2018, the most prolific planet discovery facility has been NASA’s ongoing Transiting Exoplanet Survey Satellite (TESS) mission. TESS is an all-sky survey designed to detect planets around bright, nearby stars by providing high-cadence, precision photometry for hundreds of thousands of targets. TESS is optimized to detect planets around low-mass stars (M dwarfs), and my work focuses on the detection and characterization of such worlds. As the most common stellar type—with strong planet signals in both radial velocity and transit—M dwarf stars are ideal targets for exoplanet searches. However, transit searches and planet characterization around M dwarfs are complicated by stellar magnetic activity. Furthermore, the conditions on M dwarf planets differ significantly from those in our Solar System, presenting a compelling comparison in our search for life in the Universe. In this talk, I will describe my research on detecting and characterizing planets orbiting M dwarf stars. In particular, I will discuss my work on the TOI-700 system, which hosts two small planets in the star’s habitable zone. I will cover the discovery of the four planets in the TOI-700 system using TESS data, as well as my ongoing efforts to measure their masses using data from the ESPRESSO spectrograph.
Host: John Stupak
Title: "The Pacific Ocean Neutrino Experiment"
Abstract: Every time researchers have pushed the energy boundary in particle physics we have found something new about our Universe. Recently, IceCube has demonstrated that Neutrino Telescopes can use neutrinos from the cosmos as excellent tools to continue this exploration. To unlock the true potential of this field, advanced detectors are needed that will push the forefront of the cosmic frontier, revealing new knowledge of extreme astrophysical phenomena, including through multi-messenger follow-up programs, and testing fundamental physics at scales well beyond those reachable by Earth-bound accelerators. We aim to construct one of the largest neutrino telescopes deep in the northern Pacific Ocean off the coast of British Columbia, the Pacific Ocean Neutrino Experiment (P-ONE). The first detector line is planned to be deployed this year - marking the start of an exciting phase for this new project. In this talk I will cover results from early pathfinder missions and discuss the status of P-ONE.
Host: Arne Schwettmann
Title: "Atomic Clocks"
Abstract: Atomic clocks enable many of the technologies we enjoy every day. I will talk about how general atomic clocks function and present methods for characterizing their performance. Details on our highest-performing clocks, the cesium beam tube and active hydrogen maser, will be presented. Current research efforts on improved clocks will also be discussed.
Title: "Exploring Energy Frontier from LHC to Future Colliders: Illuminating Dark Matter, Innovating Tracking Algorithms, and Inventing Future detector technologies"
Abstract: The discovery of the Higgs boson by the CMS and ATLAS collaborations in 2012 marked the completion of the Standard Model of Particle Physics—yet, in many ways, it was just the beginning. The universe continues to pose profound mysteries that the Standard Model cannot explain, leaving us with compelling questions about the nature of dark matter, the imbalance of matter and antimatter, and the possible existence of new fundamental forces.
In this talk, I will delve into one of the most enigmatic pieces of this puzzle: dark matter. Despite overwhelming astrophysical evidence of its existence, we have yet to detect it directly. I will discuss some of the ongoing efforts at the LHC to unveil its secrets, including novel search strategies and advanced data analysis techniques.
Beyond the search for dark matter, progress in high-energy physics hinges on technological breakthroughs. I will highlight the crucial role of detector R&D, particularly in particle tracking, and its impact on enhancing sensitivity in the upcoming High Luminosity LHC era. Additionally, I will delve into the transformative role of machine learning and deep learning in high-energy physics, where vast datasets are harnessed to push the boundaries of discovery.
As we continue our exploration of the unknown, the question arises: what comes after the LHC and HL-LHC? I will introduce the vision for future colliders, with a focus on the Muon Collider proposal and my contributions to its development. Finally, I will present a forward-looking perspective on my research, outlining the key challenges and opportunities that lie ahead in the quest for new physics.
Title: "Boosted Higgs Boson: A Gateway to New Physics"
Abstract: The Higgs boson, the cornerstone of the Standard Model, was discovered in 2012 at the Large Hadron Collider (LHC), marking a groundbreaking milestone in high-energy physics. Yet, critical questions—such as the origin of electroweak symmetry breaking and the mass hierarchy—remain unanswered. Precision measurements of the Higgs boson and its interactions, especially at high energies, offer one of the most promising pathways to uncover new physics at the LHC.
The most favored Higgs boson decay to a bottom-antibottom quark pair (H → bb) is emerging as a key channel for studying Higgs bosons produced with large momentum, where the decay products are reconstructed as a single, large-radius jet. Historically, hadronic final states have faced significant challenges due to contamination from QCD processes, but advancements in jet substructure and tagging techniques have made these analyses viable in the boosted topology. In this talk, I will present the first measurement of Higgs production in association with a vector boson in the fully hadronic (qqbb) final state.
Looking ahead, I will discuss opportunities to improve measurements of highly energetic Higgs bosons and explore the physics potential of the High Luminosity LHC, the ATLAS detector upgrade, and future collider projects. These advancements will deepen our understanding of Higgs boson properties and their implications for physics beyond the Standard Model, paving the way for discoveries in the years to come.
Title: "Searching for imprints of new physics at the LHC"
Abstract: Designed to revolutionize our understanding of fundamental physics, the CERN LHC is the largest and most powerful particle accelerator in the world. The discovery of the Higgs boson at the LHC confirmed the final piece of the remarkably successful Standard Model of particle physics. Yet, the Standard Model does not provide a complete description of nature, motivating further searches for new particles at the LHC. This presentation will introduce a comprehensive search strategy aimed towards maximizing the discovery potential of the LHC. By incorporating multi-sector measurements in a systematic way, this approach is designed to be sensitive to the subtle imprints of new physics, allowing us to reach beyond the energy range directly accessible at the LHC. Looking ahead towards the upcoming era of high-luminosity LHC data-taking, we will discuss how R&D of cyberinfrastructure will enable us to pursue even more global searches with this strategy at unprecedented scale and complexity, exploring new and rarer regions as we chart a course towards new discoveries at the LHC and beyond.
Title: "Probing the Lifetime Frontier at the Large Hadron Collider and Beyond"
Abstract: It is widely recognized that the Standard Model (SM) of particle physics is not a complete description of the interactions of fundamental particles. And yet, after over a decade of intense scrutiny, the experiments at the Large Hadron Collider (LHC) have produced no definitive evidence of physics beyond the SM. The vast majority of searches for beyond SM physics have targeted heavy, strongly interacting particles that decay almost instantaneously back to SM particles. However, many models propose the existence of new long-lived particles (LLPs) that can travel significant distances before decaying, yielding unconventional detector signatures that may be overlooked by common search techniques. Searches for LLPs decaying in the ATLAS inner detector (ID) are crucial for providing experimental sensitivity to a broad range of LLP lifetimes, but also must overcome challenges posed by the reconstruction of displaced charged particle trajectories (tracks). Recently, breakthroughs in ATLAS track reconstruction have revolutionized the inner tracking detector's ability to identify LLP decays and invigorated the ATLAS LLP search program. In this colloquium, I will highlight the recent advancements in displaced track reconstruction and present the latest search results for LLP decays in the ATLAS ID. Additionally, I will discuss prospects for expanding the LLP search program with new dedicated search experiments that will provide unique sensitivity to low-mass LLPs, and explain why there is reason to be optimistic about the future of particle physics beyond the LHC.
Title: "From Particles to Patterns: High Energy Physics in the Era of Machine Learning"
Abstract: Machine learning is becoming an evermore present aspect in our daily lives, and this is also true within high-energy physics research where the large-scale of complex data processed by modern experiments is perfectly suited for such tools. In particular jets, collimated sprays of particles resulting from proton collisions at the LHC, are the most abundant and complex signatures seen by the ATLAS experiment. Distinguishing different types of jets, such as those from heavy particles like top quarks and the Higgs boson, is a fundamental challenge in experimental high-energy physics. In this talk, I will explore how recent advancements in machine learning have revolutionized how we approach such problems and achieved unprecedented improvements in physics measurements. I will also touch upon key challenges, such as interpretability, robustness, and domain adaptation of these algorithms.
Title: "Primordial Black Holes as Dark Matter Candidates: Production Mechanisms and Detection Strategies"
Abstract: Primordial black holes (PBHs) provide an exciting prospect for accounting for dark matter. They can be produced with masses in the range required to address the present-day dark matter abundance by inflationary models that incorporate realistic features from high-energy physics and that also provide an excellent match with high-precision measurements of the cosmic microwave background radiation. Such PBHs would form well before the QCD confinement transition, and hence the black holes would form by absorbing unconfined quarks and gluons. A subpopulation of the resulting PBHs would therefore acquire a net QCD color charge; some would be extremal. Meanwhile, if PBHs do constitute a significant fraction of the present dark-matter abundance, then we may expect at least one PBH to cross through the inner Solar System per decade. Such close encounters would produce detectable perturbations to orbital trajectories of closely-tracked, visible Solar System objects such as the planet Mars. By exploiting high-precision data on the motions of various objects within the Solar System, PBHs within the (as yet) unconfined “asteroid-mass’” range could plausibly be detected within the next decade, or their absence used to strengthen present-day bounds. (Based on https://arxiv.org/abs/2303.02168, https://arxiv.org/abs/2310.16877, and https://arxiv.org/abs/2312.17217.)
Title: "From particle collisions to new physics"
Abstract: The Standard Model (SM) of particle physics is a remarkably successful theory describing particles and fundamental forces. Its many predictions were fulfilled, with the Higgs boson being the last missing piece found with the Large Hadron Collider (LHC) in 2012. Despite its many successes, we know that the SM is incomplete as it does not explain dark matter, or matter-antimatter asymmetry, among other questions. To explore rare processes and search for particles of higher mass, CERN and the High Energy Physics community work to increase the energy and luminosity of the LHC (High-Luminosity LHC). The experiments, like ATLAS, also need to be upgraded to follow the development of the HL-LHC. This talk will guide you through the search for new physics using the HL-LHC and the ATLAS detector as an example. The general concepts of particle detection and the upgrades of the ATLAS detector required to meet the challenge from the upgrade of the LHC to the HL-LHC will be presented. Particular attention will be given to the Inner Tracker (ITk) Pixel subsystem to be installed in the ATLAS detector in the next five years. The designed performance will be discussed, and its impact on the analysis of the data collected during Run 4 (2030-2035) of the HL-LHC.
Host: Doerte Blume
Title: "How to Win Friends and Influence Cold Molecules"
Abstract: A relatively new frontier in physics is that of ultracold molecules, that is, gaseous samples whose temperature is hundreds of nanoKelvin above absolute zero. In such an environment, the molecules move so slowly that their interactions are governed by forces that would be negligible in, say, a room temperature gas. This gives experimentalists the ability to control molecular collisions, for example to prevent molecules from reacting chemically, or else to assemble pairs of molecules into larger molecules. In this talk I will explore the basic physics of how this control is possible, and why someone might want to exert it.
