Have you ever left a colloquium or a seminar and thought to yourself “that was interesting, but it wasn’t physics”? If so, you are in good company, because there has long been disagreement in our community about which research specialties belong to the canon of physics and which do not, particularly when it comes to hiring faculty members into physics departments to train PhD students. In this talk, I discuss some aspects of this debate from the founding of the American Physical Society to the present day. Examples include a field that was once a part of physics but is not anymore; a field that was once “not physics” but is definitely so today; and a field whose status as “physics” remains unsettled in the minds of many.

With the completion of the Standard Model (SM), Particle Physics stands at a crucial point, where a successful theory framework is faced with a collection of mysteries, contradictions, and unexplained curiosities. Physics at today’s high energy particle collider, the Large Hadron Collider, is a mixture of testing every prediction of the SM and directly searching for signatures that would require a rewrite of our textbooks and symmetries. This talk will describe the broad motivation for my research program today with a focus on unconventional collider signatures, machine learning, and the technical challenges for a future muon collider – a program designed to address both the questions the SM doesn’t answer, and those it doesn’t even ask.

There is no colloquium on September 1.

Fusion energy promises to be a transformative, long-term solution to global energy needs—offering abundant, safe, and carbon-free power. This talk will introduce the fundamentals of fusion, the technical challenges of harnessing it for practical energy production, and the strategies being pursued to overcome these challenges. The talk will highlight recent progress in both public and private sector efforts and outline the path toward a fusion pilot plant. I will highlight the challenges in plasma physics, plasma-materials interaction, and condensed matter/materials science that represent opportunities for collaboration between UT and ORNL.

Dominant narratives in introductory physics education often focus on student preparation in mathematics. Students who have not reached a certain level of proficiency as determined by math placement tests are often labeled as underprepared. In this presentation, I will challenge this narrative by reframing the notion of underprepared. Indeed, many physics departments and instructors are underprepared to support the students accepted into their institutions. The Transforming Introductory Physics Sequences to Support all Students (TIPSSS) Network is a network of physicists developing curricular materials, transforming courses, and research the effectiveness of these efforts to help departments meet the needs of their physics students, regardless of the students’ prior mathematics preparation. I will present and overview of the TIPSSS activities and also preliminary findings from the TIPSSS studies.

Although the astrophysical origin of elements is a longstanding mystery, neutron capture processes are known to be a crucial mechanism by which nucleosynthesis can overcome the repulsive forces associated with adding another proton to a nucleus. Studies have identified at least three neutron capture processes believed to be taking place in astrophysics: the slow (s), rapid (r), and intermediate (i) neutron capture processes. Not only are the site(s) of the r and i processes under active study, but open questions remain regarding how much each of these contributed to the overall enrichment of stars such as our Sun. In particular, the r process synthesizes exotic and unstable nuclei that have yet to be probed in terrestrial experiments. Thus r-process studies must consider how uncertainties in the nuclear physics data propagate to the interpretation of observables. In this talk I will discuss how observables such as stellar abundance patterns and signals from multi-messenger events such as MeV gamma rays can be used to inform r-process studies. I will show how recently reported nuclear masses from experiments and cutting-edge nuclear theory change our picture for the abundance of key elements (e.g. gold) produced in sites such as neutron star mergers. I will also discuss new applications of machine learning to nucleosynthesis problems. Novel, interdisciplinary work at the intersection of observation, experiment, theory, and computational science are key to carving out the new ideas and tools needed to modernize heavy element nucleosynthesis studies.

When a nucleus is permanently deformed, it exhibits a characteristic rotational band, in which the excitation energies of a state with spin I is proportional to I(I+1). It also shows enhanced electromagnetic transition strengths as well as large quadrupole moments. Moreover, it has also been well known that nuclear deformation significantly affects low-energy nuclear reactions. In particular, heavy-ion fusion reactions at energies around the Coulomb barrier are sensitive to nuclear deformation, and there have been many attempts to determine deformation parameters of a nucleus. In recent years, there has also been increasing interest in probing nuclear deformation in relativistic heavy-ion collisions.

In this talk, I will discuss recent theoretical developments in low-energy heavy-ion reactions, putting emphasis on nuclear deformation. This includes i) a new attempt to visualize nuclear scattering and ii) an emulator for multi-channel scattering. I will also discuss the role of shape dynamics in relativistic heavy-ion collisions.

Dark matter is thought to make up 25% of the universe. Dark sector particles (DSP) do not interact through the known forces but could be weakly coupled to Standard Model particles through a portal or a mediator (Dark Messenger) that could provide access to the dark matter world. Many searches for these particles at an accelerator thus far seem to face a ceiling that the sensitivity reach is greatly limited, beyond statistical effects. DAMSA (DArk Messenger Searches at an Accelerator) is an extremely short baseline, table-top scale experiment that aims to break through this limit. The experiment plans to take advantage of high beam powers available at various accelerator facilities around the world, including the PIP-II LINAC under construction at Fermilab near Chicago, an essential element in providing the necessary high flux proton beams to the $3.5B U.S. flagship neutrino experiment, DUNE. In this talk, I will describe the DAMSA experiment and discuss the current status and plan for DAMSA, as well as its expected sensitivity reach on the search of the Axion-Like Particle, a dark messenger, as a benchmark physics case.

All living cells are bounded by envelopes that protect them from the environment and confer their sizes and shapes. These shapes help cells to spatially organize their internal biological processes, allowing them to divide and faithfully segregate genetic material to each daughter. Yet, we still know very little about how cells obtain and control cell shape, even in the arguably simplest and best understood organism: the rod-shaped Escherichia coli. To resist a high intracellular osmotic pressure, bacteria and many other single-celled organisms are surrounded by a cell wall, an elastic, covalent meshwork of sugars and peptides. For walled cells to grow, they must enzymatically cut cell-wall bonds while inserting new cell-wall material to prevent envelope rupture. In some bacteria and many fungi and plants, the process of cell-wall remodeling is limited to the tip of the cell, where intracellular pressure and enzymatic cell-wall fluidization drive growth of the rod, akin to glass blowing. However, in E. coli and many other rod-shaped bacteria, cell-wall remodeling happens all along the cylindrical part of the cell, while the poles remain inert (new poles being constructed at mid-cell during division). How do cells control a straight rod-like cell geometry with a well-defined diameter, all the while increasing cell length at a rate that accommodates biomass growth? While the ultimate answers to these questions remain to be found, we have made important progress in the past two decades. For example, i) curved cytoskeletal polymers sense cell-envelope curvature and reenforce cylindrical geometry, ii) mechanical stress affects envelope growth locally, and iii) the ratio between cell-surface area and biomass emerges as a controlled variable, thus coupling the global rate of envelope growth to the rate of biomass growth. I will present these and other findings, illustrate the importance of experiments and theory, and present future directions.

The weak force of nature uniquely allows quarks to change flavor, resulting in the transformation of nuclei known as nuclear beta decay. Currently, measurements of the weak mixing of quarks are in tension with the Standard Model’s description, a discrepancy referred to as the “Cabibbo Angle Anomaly.” As the simplest nucleus to undergo beta decay, the neutron has emerged as a system which can provide a competitive measurement and shine light on this anomaly if experimental uncertainties in the neutron dataset can be improved. The Nab experiment at the Spallation Neutron Source employs a novel and robust approach to improve decay correlation measurements by observing the full momentum phase space in neutron beta decay accessible above detection thresholds. The tight kinematic constraints from the experiment have recently been used to place first limits on a new hypothesized excited state of the neutron, suggested to address experimental disagreements in neutron lifetime measurements. In this presentation, I will describe the working principles of the experiment, present early results from first physics data-taking, and discuss the outlook for Nab and its upgrade pNAB (polarized Nab) to perform world-leading measurements of neutron decay correlations and improve our understanding of quark mixing in the weak interaction.

The detection of GW170817 enabled us to track down and watch the cataclysmic event in multiple wavelengths of light, allowing us to scrutinize the source of these cosmic ripples for the first time. This discovery provided the first solid evidence that neutron-star smashups are the source of much of the Universe’s gold, platinum, and other heavy elements. With a single event, we were able to answer fundamental questions in general relativity, cosmology, nuclear physics, and astrophysics. However, other aspects of the story, as revealed by these events, are still shrouded in mystery. For astronomers and physicists across disciplines, this is a fascinating time to be alive.

Observations spanning multiple astronomical scales point to the existence of an unknown form of matter, dubbed “dark matter”, that constitutes over 85% of the mass of most galaxies. Recent theoretical insights into the possible nature of dark matter and how it interacts with normal matter have inspired a wide range of experimental efforts aimed at directly detecting dark matter. As part of this effort, we are developing a small-scale experiment to search for multiple well-motivated “ultralight” dark matter candidates, placing stronger bounds than are currently possible with high-cost and/or large-scale efforts. The core enabling technology relies on microwave cavity readout of mechanical motion in superfluid helium. I will tell you about the experiments that have led up to where we are now, and our current efforts with regards to this table-top dark matter search.

Magnetism is the posterchild of how the interplay between electron-electron interactions and quantum physics promotes novel macroscopic phenomena. Historically, the evolution of our understanding of magnetism has been related to the discovery of new paradigms in condensed-matter physics, as exemplified by the connections between antiferromagnetism and Mott insulators, spin glasses and non-ergodic states, and spin liquids and fractionalized excitations. Recently, a new framework proposed to classify magnetic phases brought renewed interest in unconventional magnetic states, which are qualitatively distinct from ferromagnets and standard Néel antiferromagnets. Among those, altermagnetic phases have been met with enthusiasm by the scientific community, as they display properties found in both ferromagnets (like the splitting of electronic bands with opposite spins) and conventional antiferromagnets (like the absence of a net magnetization). Formally, what distinguishes these three different magnetic states are the crystalline symmetries that, when combined with time reversal, leave the system invariant. In the case of altermagnets, because these symmetries involve rotations, the system is endowed with unique properties such as nodal spin-splitting and piezomagnetism. In this talk, I will introduce the concept of altermagnetism and discuss its connection to long-standing problems in the field of quantum materials, such as multipolar magnetism and electronic liquid-crystalline phases. I will also present the predicted experimental signatures of altermagnetic order in thermodynamic and transport properties, and show that altermagnets provide a fertile ground to realize non-trivial topological and superconducting phenomena in quantum materials.

Observing neutrinoless double-beta decay (0νββ) would confirm the neutrino has a Majorana nature and offer critical evidence to understanding the universe’s matter/antimatter asymmetry. The LEGEND collaboration targets half-lives greater than T1/2>1028 years using the high-purity germanium (HPGe) detectors enriched in the isotope 76Ge. Achieving this unprecedented sensitivity – 18 orders of magnitude beyond the age of the universe – requires a detector environment with exceptionally low background radiation. While HPGe detectors are central to the measurement, sensitivity to 0νββ decay hinges on the scintillating materials surrounding them to actively detect and reject ambient background radiation.

This seminar explores the critical role of radiopure scintillating materials in LEGEND, focusing on poly(ethylene-2,6-naphthalate) (PEN). We will present technical results detailing the radiopurity, scintillation performance, and mechanical stability of these materials, highlighting their successful deployment as both a structural element and an active background veto in LEGEND-200. Furthermore, we will detail ongoing efforts in additive manufacturing to realize complex, ultra-pure components for the future LEGEND-1000 phase.

Beyond these technical results, we will discuss the opportunities of cross-disciplinary collaboration, bridging the fields of material science and particle physics to solve unique and complex challenges vital for fundamental discovery. This talk will conclude with a discussion on the communication journey of working on an “enabling technology” within the framework of a large-scale collaboration, with insights on how to effectively communicate the profound scientific impact of support technologies.

Nearly thirty years after the Nobel-prize-winning discovery of the exoplanet 51 Pegasi b, astronomers have discovered thousands of planets outside the solar system, and the field of exoplanetary astronomy has shifted from purely being driven by discovery to performing demographic analysis, and detailed characterization of properties like mass, radius, and atmospheric composition. However, even today, basic questions remain, like “why do some systems end up looking like the Solar System with orderly co-planar architectures, with small planets close-in, and giant planets orbiting far from their stars, while others, like the so-called Hot Jupiters, are dramatically different?” My team and I are tackling this question from both sides: understanding the evolutionary origins of hot Jupiters and understanding the properties of compact multi-planet systems. Using data from NASA’s Transiting Exoplanet Survey Satellite (TESS) and Kepler/K2 missions, we are working to find keystone planetary systems around bright stars (those well suited for atmospheric observations) that can help address specific questions about planet formation and evolution. I will review our efforts to discover and characterize hundreds of hot Jupiters while investigating the compact architectures of small rocky planets. Finally, uncertainty in planetary orbital solutions for hundreds of planets have accumulated since their initial detection to the extent that they are not accessible with the James Webb Space Telescope (JWST) to study their atmospheres. I will also discuss how we are addressing this problem on a large scale to make hundreds of planets accessible for JWST.