The University of Mississippi
Department of Physics and Astronomy

Seminars/Colloquia, Fall 2021

Unless noted otherwise, Tuesday Colloquia are at 4:00 PM
Scheduling for additional seminars will vary.

For the Online colloquia, please join Zoom Meeting:
https://olemiss.zoom.us/j/91928227187
Meeting ID: 919 282 27187

Date/Place Speaker Title (and link to abstract)
Tue, Aug 24
Outside or Lewis 101
Department Faculty
Department of Physics and Astronomy
University of Mississippi
Ice Cream Social. (PDF)
Tue, Aug 31
Lewis 101
Jake Bennett, etc.
Department of Physics and Astronomy
University of Mississippi
What can you do with a Physics degree?
Tue, Sep 7
Lewis 101
Martin Frank
Department of Physics
University of South Alabama
First Results from NOνA's Magnetic Monopole Search
Tue, Sep 14
Lewis 101
Shawn Pollard
Department of Physics and Materials Science
University of Memphis
Designing Chiral Magnetism Through Interface Engineering – From Skyrmions to Magnetic Memory
Tue, Sep 21
Lewis 101
 
 
 
 
Tue, Sep 28
Lewis 101
Samrat Choudhury
Department of Mechanical Engineering
University of Mississippi
Machine Learning Enabled Multi-Scale Modeling of Materials
Tue, Oct 5
Lewis 101
Jake Bennett, Gavin Davies, Anuradha Gupta, and John Waite
Department of Physics and Astronomy
University of Mississippi
Preparing for Job Interviews (including mock interview examples)
Tue, Oct 12
Lewis 101
 
 
 
 
Tue, Oct 19
Lewis 101
Sudeep Adhikari & John Waite
Department of Physics and Astronomy
University of Mississippi
Sudeep Adhikari: Universality in Activated Barrier Crossing
John Waite: Flavor SU(3) in Cabibbo-favored D-meson Decays
Tue, Oct 26
Lewis 101
Zara Bagdasarian
Department of Physics
University of California — Berkeley
Reaching for the Stars with CNO Solar Neutrinos and Other Adventures of Novel Neutrino Detectors
Tue, Nov 2
Lewis 101
Alexandru Lupsasca
Department of Physics
Princeton
The Black Hole Photon Ring
Tue, Nov 9
Lewis 101
 
 
 
 
Tue, Nov 16
Lewis 101
Kathy Gunn
Department of Oceanography
Commonwealth Scientific and Industrial Research Organisation (Australia)
Vertical Mixing and Heat Fluxes Conditioned by a Seismically Imaged Oceanic Front
Tue, Nov 23
Lewis 101
Thomas Turkey
Department of Nutrition
Virginia Tech
Continuing Advantages of a Vegetarian Diet
Tue, Nov 30
Lewis 101
Saptaparna Bhattacharya
Department of Physics and Astronomy
Northwestern University
An Experimental Overview of Effective Field Theory Exploration at the LHC
Tue, Dec 7
Lewis 101
Final Exam Week  

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The physics colloquium organizer is Gavin Davies
This page is maintained by David Sanders
Latest update: Monday, 29-Nov-2021 12:13:42 CST

Past semesters: 

Abstracts of Talks


Jake Bennett, etc.
Department of Physics and Astronomy
University of Mississippi

What can you do with a Physics degree?

Undeclared, interested in exploring other majors, or just curious about the Department of Physics and Astronomy? Want to prepare for professional school or just develop the tools and qualities employers value most? Join us to discover what a degree in Physics can do for you. You will also get the chance to observe some fun and interesting demonstrations.


Martin Frank
Department of Physics
University of South Alabama

First Results from NOνA's Magnetic Monopole Search

The existence of the magnetic monopole has eluded physicists for centuries. The NOνA far detector (FD), used for neutrino oscillation searches, also has the ability to identify slowly moving magnetic monopoles (v < c /100). With a surface area of 4,100 m2 and a location near the earth's surface, the 14 kt FD provides us with the unique opportunity to be sensitive to potential low-mass monopoles unable to penetrate underground experiments. We have designed a novel data-driven triggering scheme that continuously searches the FD's live data for monopole-like patterns. At the offline level, the largest challenge in reconstructing monopoles is to reduce the 148,000 Hz speed-of-light cosmic ray background. In this talk, I will present the first results of the NOνA monopole search for slow monopoles.


Shawn Pollard
Department of Physics and Materials Science
University of Memphis

Designing Chiral Magnetism Through Interface Engineering – From Skyrmions to Magnetic Memory

Chirality is a fundamental concept in condensed matter physics. The ability to control magnetic chirality through broken symmetry at interfaces has led to the development of new devices governed by control of the local spin structure. One such structure, the skyrmion, a result of the Dzyaloshinskii-Moriya interaction (DMI), has been proposed as both a building block of new spintronic devices and as a tool to probe a variety of novel electrical transport phenomena. In this talk, I will describe our efforts to design chiral structures including skyrmions with tunable stability and dynamics by modifying the interface properties in both heavy metal/ferromagnet bi- and multilayers. We find that by tuning the heavy metal and ferromagnetic layer thicknesses and repetition numbers, we can control the skyrmion boundary structure, which has profound effects on its dynamics. This includes the first observation of an interlayer DMI in which a breaking of domain wall degeneracy can be used to prevent off-axial current driven skyrmion motion known as the skyrmion Hall effect. I also discuss our work developing new techniques in which to quantify magnetic phenomena in these materials.


Samrat Choudhury
Department of Mechanical Engineering
University of Mississippi

Machine Learning Enabled Multi-Scale Modeling of Materials

Traditional computational investigation of processing-chemistry-structure-property linkage in materials science involves the usage of specialized computational tools at discrete length scales ranging from electronic to atomic to mesoscale. Alternatively, over the past two decades, a multi-length scale approach combining simulation tools at different length scales has been adopted where electronic/atomic information from lower length scale is passed to higher length scale. However, such traditional computational approaches can provide only limited insights into a highly complex set of interactions spanning over multiple length and time scales each of which are linked to the property and performance of the materials, thus requiring an out-of-the box approach. In this presentation, I will focus on the application of machine learning tools to guide simulations at multiple length scales to augment the capabilities of traditional computational tools. Further, it will be shown that machine learning enabled computational approach provides a fast and efficient pathway to navigate the vast processing, microstructure and chemical search space for a targeted property, a departure from the traditional time consuming and expensive Edisonian trial-and-error approach based on synthesis-testing experimental cycles.


Sudeep Adhikari
Department of Physics and Astronomy
University of Mississippi

Universality in Activated Barrier Crossing

The thermal activation process by which a system passes from one local energy minimum to another by crossing an energy barrier is a recurring motif in physics, chemistry, and biology. For instance, biopolymer chains are typically modeled in terms of energy landscapes, with folded and unfolded configurations represented by two distinct wells separated by a barrier. The rate of transfer from the unfolded to folded state depends most importantly on the height of the barrier with respect to the temperature of the heat bath—but also in seemingly idiosyncratic ways on the details of the shape of the barrier. We consider the case of bias due to an external force, analogous to the pulling force applied in optical tweezer experiments on biopolymers. We identify the universal behavior of the barrier crossing process and demonstrate that data collapse onto a universal curve can be achieved for simulated data over a wide variety of energy landscapes having barriers of different heights and shapes.


John Waite
Department of Physics and Astronomy
University of Mississippi

Flavor SU(3) in Cabibbo-favored D-meson Decays

Model-independent description of nonleptonic decays of charmed mesons is a challenging task due to the large nonperturbative effects of strong interactions on the transition amplitudes. We discuss the equivalence of two different flavor-SU(3)-based descriptions of Cabibbo-favored non-leptonic decays of charmed mesons to two-pseudoscalars final states including the η and η′ mesons.


Zara Bagdasarian
Department of Physics
University of California — Berkeley

Reaching for the Stars with CNO Solar Neutrinos and Other Adventures of Novel Neutrino Detectors

The latest breakthrough in neutrino physics is the first experimental evidence of the carbon-nitrogen-oxygen (CNO) fusion cycle in the Sun. The discovery was possible due to the unprecedented radiopurity of the Borexino liquid-scintillator detector (Italy), employing innovative hardware and software developments. In the future, new technologies can further facilitate access to a broad physics agenda and applications in neutrino physics. Of particular interest are the cutting-edge detection techniques and novel target materials that aim to fully utilize both scintillation and Cherenkov signals from low- and high-energy neutrino interactions. The first deployment of Large Area Picosecond Photodetectors (LAPPDs) and water-based liquid scintillator (WbLS) in the ANNIE experiment at Fermi National Accelerator Laboratory (USA) will be exciting milestones in the evolution of neutrino detection. Neutrino Experiment One (NEO) will be the first ktonne-scale detector built by the Watchman collaboration at Boulby Underground Laboratory (UK). Its goal is to demonstrate, for the first time, nuclear non-proliferation capabilities using antineutrino detection. Finally, the multi-ktonne detector, Theia, aims to detect solar neutrinos, determine neutrino mass ordering and the CP-violating phase, observe diffuse supernova neutrinos and neutrinos from a supernova burst, search for nucleon decay, and, ultimately, neutrinoless double beta decay.


Alexandru Lupsasca
Department of Physics
Princeton

The Black Hole Photon Ring

The photon ring is a narrow ring-shaped feature, predicted by General Relativity but not yet observed, that appears on images of sources near a black hole. It is caused by extreme bending of light within a few Schwarzschild radii of the event horizon and provides a direct probe of the unstable bound photon orbits of the Kerr geometry. I will review the origin and structure of the photon ring, before discussing the prospects for its future detection. I will argue that the precise shape of the observable photon ring is remarkably insensitive to the astronomical source profile and can therefore be used as a stringent test of strong-field General Relativity. A space-based interferometry experiment targeting the photon ring of M87* could test the Kerr nature of the source to the sub-sub-percent level.


Kathy Gunn
Department of Oceanography
Commonwealth Scientific and Industrial Research Organisation (Australia)

Vertical Mixing and Heat Fluxes Conditioned by a Seismically Imaged Oceanic Front

The southwest Atlantic gyre connects several distinct water masses, which means that this oceanic region is characterized by a complex frontal system and enhanced water mass modification. Despite its significance, the distribution and variability of vertical mixing rates have yet to be determined for this system. Specifically, potential conditioning of mixing rates by frontal structures, in this location and elsewhere, is poorly understood. Here, we analyze vertical seismic (i.e., acoustic) sections from a three-dimensional survey that straddles a major front along the northern portion of the Brazil-Falkland Confluence. Hydrographic analyses constrain the structure and properties of water masses. By spectrally analyzing seismic reflectivity, we calculate spatial and temporal distributions of the dissipation rate of turbulent kinetic energy, ε, of diapycnal mixing rate, K, and of vertical diffusive heat flux, FH. We show that estimates of ε, K, and FH are elevated compared to regional and global mean values. Notably, cross-sectional mean estimates vary little over a 6 week period whilst smaller scale thermohaline structures appear to have a spatially localized effect upon ε, K, and FH. In contrast, a mesoscale front modifies ε and K to a depth of 1 km, across a region of O(100) km. This front clearly enhances mixing rates, both adjacent to its surface outcrop and beneath the mixed layer, whilst also locally suppressing ε and K to a depth of 1 km. As a result, estimates of FH increase by a factor of two in the vicinity of the surface outcrop of the front. Our results yield estimates of ε, K and FH that can be attributed to identifiable thermohaline structures and they show that fronts can play a significant role in water mass modification to depths of 1 km.


Saptaparna Bhattacharya
Department of Physics and Astronomy
Northwestern University

An Experimental Overview of Effective Field Theory Exploration at the LHC

The effective field theory (EFT) approach posits that in a scenario where new particles cannot be observed directly at low energy, the source of new physics are heavy fields beyond our current reach. The Standard Model (SM) Lagrangian contains fields of dimension-4 and the EFT frame-work extends the SM Lagrangian in an expansion in inverse powers of the scale of new physics. Within this framework, the potential impact of higher dimensional operators can be explored. The most common example of an EFT appears in the Fermi theory of weak interactions where the appearance of the four Fermi vertex features an operator of dimension-6. In this talk, I will provide an overview of EFT explorations at the LHC. With the collection of more than 150 fb-1 of data at the LHC, rare processes predicted in the Standard Model have become accessible. These rare processes can be used as probes of new physics using the EFT framework. The large dataset also enables precision measurements of certain processes allowing the ability to study deviations from SM expectations and characterizing the nature of potential excesses within the EFT formalism. I will focus on the exploration of dimension-6 and dimension-8 operators at the LHC in final states arising out of the decay of multiple gauge bosons. I will provide a snapshot of LHC Run II analyses as we embark on Run III.