Events

Tue23Jan20184:00 pmLewis 101
Jake Bennett
Department of Physics
Carnegie Mellon UniversityAmplitude Analysis: A Powerful Tool for Hadron Spectroscopy
Extracting useful information from experimental data is often far from straightforward. This is particularly true for studies in hadron spectroscopy that seek to determine the properties of constituent quark states. The presence of multiple, often broad, states leads to potentially intricate interference patterns that make the extraction of meaningful information challenging. Amplitude analysis is a powerful tool to disentangle the effects of interference and extract useful properties of hadronic states. This information is vital for a deeper understanding of the fundamental laws of nature. In this talk, I will review the experimental challenges that are associated with amplitude analysis, as well as its potential as a tool for hadron spectroscopy at Belle II.

Tue30Jan20184:00 pmLewis 101
Brian Anderson
Department of Physics and Astronomy
Brigham Young UniversityListening For Cracks Using Resonance And Time Reversal Techniques To Prevent Radiation Leakage From Nuclear Storage Containers
Spent nuclear fuel is often stored in stainless steel canisters in the United States. Stainless steel is susceptible to Stress Corrosion Cracking (SCC). This presentation will discuss progress on the use of the Time Reversed Elastic Nonlinearity Diagnostic (TREND) and Nonlinear Resonant Ultrasound Spectroscopy (NRUS) to determine whether SCC is present and attempt to quantify the depth of the cracking. NRUS is the measurement of the amplitude dependence of a sample's resonance frequency, which occurs because of a softening of the elastic modulus in damaged media. NRUS provides a global indication of damage in a sample. TREND employs time reversal acoustics, which focuses wave energy at various points of interest to excite localized high amplitude. The amplitude dependence of this localized energy allows pointwise inspection of a sample.

Thu08Feb20184:00 pmNCPA Auditorium
Aaron Zimmerman
Canadian Institute for Theoretical Astrophysics
University of TorontoBlack Holes, Alone and in Pairs
The recent detections of gravitational waves have revealed an invisible side of the universe: black holes in binaries. These observations test our understanding of black holes, their violent mergers, and the theory of general relativity. A combination of analytic approximations and full numerical simulations is required to understand black hole binaries and predict the gravitational waves they emit. I will take us on a tour of these systems, discuss the “ringdown” of the final merged black hole, and present the most recent results from the Advanced LIGO and Virgo detectors.

Thu15Feb20184:00 pmLewis Hall 101
Jessica McIver
Division of Physics, Mathematics and Astronomy
California Institute of TechnologyGravitational Wave Astrophysics: A New Era of Discovery
Largescale interferometric detectors including LIGO and Virgo sense gravitational waves; minuscule fluctuations in spacetime from the most extreme phenomena in the Universe. The recent detection of gravitational waves by LIGO and Virgo in concert with an associated electromagnetic counterpart was a breakthrough in multimessenger astronomy that confirmed the association between neutron star collisions and short gammaray bursts (GRBs) and yielded new insight into the physical engine driving GRBs. Future gravitational wave observations have the potential to provide critical insight into key open questions in astrophysics, including the distribution of compact objects in the Universe, the evolution of compact binary systems, galaxy formation, and the explosion mechanism of corecollapse supernovae.
I will present the major outstanding challenges in gravitational wave astrophysics, including searching for transient signals in noisy data that contains a high rate of transient noise artifacts. I will discuss future prospects for how this quickly growing field will shape our understanding of the Universe.

Tue20Feb20184:00 pmLewis Hall 101
Dan Cherdack
Department of Physics
Colorado State UniversitySearching for CPViolation with the DUNE Experiment
Of the four known fundamental forces the weak force has many unique properties. It is the only standard model force that couples to all known fermions, that has massive exchange bosons, and that induces particle flavor changes. Even more surprising is that the weak force maximally violates parity symmetry, and has even been demonstrated to break chargeparity (CP) symmetry, meaning the weak force interacts differently with matter and antimatter. This last property may hold the key to understanding several fundamental mysteries of the universe from the threegeneration structure of matter, to the missing link between the big bang and the observed universe.
Neutrinos only interact via the weak force which means they are hard to detect, but provide a unique test bed for studying the weak interaction. Over the past few decades it was discovered that neutrinos have mass and change flavors. Studying the way neutrinos change flavors, termed neutrino oscillations, allows us to search for a new source of CPviolation. The nextgeneration Deep Underground Neutrino Experiment (DUNE) will usher in an era of high precision neutrino physics with the worlds most intense neutrino beam and high resolution Liquid Argon (LAr) Time Projection Chamber (TPCs) detectors. The Fermilab ShortBaseline Neutrino (SBN) Program will employ three LAr TPCs, which will provide and excellent test bed for LAr TPC R&D, and allow for many important measurements crucial to DUNE. I will discuss the theoretical framework we use to describe neutrino oscillations, and the exciting opportunities and new challenges afforded us by these experiments.

Fri23Feb2018Sat24Feb2018Lewis Hall 101 (Friday) and the Law Center (Saturday)
This is a Meeting of the Zone X region of the Society of Physics Students.

Tue27Feb20184:00 pmLewis Hall 101
Tony Jun Huang
Pratt School of Engineering
Duke UniversityAcoustofluidics: Merging Acoustics and Microfluidics for Biomedical Applications
The past two decades have witnessed an explosion in labonachip research with applications in biology, chemistry, and medicine. The continuous fusion of novel properties of physics into microfluidic environments has enabled the rapid development of this field. Recently, a new labonachip frontier has emerged, joining acoustics with microfluidics, termed acoustofluidics. Here we summarize our recent progress in this exciting field and show the depth and breadth of acoustofluidic tools for biomedical applications through many unique examples, from exosome separation to cellcell communications to 3D bioprinting, from circulating tumor cell isolation and detection to ultrahighthroughput blood cell separation for therapeutics, from highprecision microflow cytometry to portable yet powerful fluid manipulation systems. These acoustofluidic technologies are capable of delivering highprecision, highthroughput, and highefficiency cell/particle/fluid manipulation in a simple, inexpensive, cellphonesized device. More importantly, the acoustic power intensity and frequency used in these acoustofluidic devices are in a similar range as those used in ultrasonic imaging, which has proven to be extremely safe for health monitoring during various stages of pregnancy. As a result, these methods are extremely biocompatible; i.e., cells and other biospecimen can maintain their natural states without any adverse effects from the acoustic manipulation process. With these unique advantages, acoustofluidic technologies meet a crucial need for highly accurate and amenable disease diagnosis (e.g., early cancer detection and prenatal health) as well as effective therapy (e.g., transfusion and immunotherapy).

Tue06Mar20184:00 pmLewis Hall 101
Harry Swinney
Center for Nonlinear Dynamics
University of Texas — AustinUniversality in Nature
In the seventeenth century Newton thought about the gravitational force between the earth and an apple falling from a tree, and he said “I began to think of gravity extending to the orb of the Moon.” This led him to postulate that his gravitational force law is a universal law of nature, applying to any two masses in the universe. We now know that there are three other fundamental universal forces in nature, the electromagnetic and the strong and weak nuclear forces. Systems of many atoms or molecules can similarly exhibit universal behavior. For example, studies of phase transitions in the 20th century culminated with Kenneth Wilson's theory of universality in phase transitions of systems as different as fluids and magnets. The present talk examines spatial patterns that emerge in systems driven away from thermodynamic equilibrium by imposed gradients in pressure, temperature, or nutrient concentration. Experiments and mathematical models provide insights into the formation of patterns in physical, chemical, and biological systems, as will be illustrated through examples that reveal mathematical similarity in phenomena such as in the fractal wrinkling of flower petals and plastic sheets.

Tue20Mar20184:00 pmLewis Hall 101
Tyrone Porter
Department of Mechanical Engineering and Biomedical Engineering
Boston UniversityTensionless Bubbles and Exploding Droplets
Fluidfilled particles play a pivotal role in biomedical applications of ultrasound. This talk will cover two examples, lipidcoated microbubbles and vaporizable nanoemulsions, highlighting their interesting nonlinear dynamics and utility. Due to their compressibility, microbubbles are more echogenic than tissue, making them ideal ultrasound contrast agents. The microbubble surface must be coated with surfaceactive molecules such as lipids in order to reduce the interfacial tension and stabilize the microbubble against dissolution. The interfacial tension is a function of lipid surface density, which varies from zero upon deep compression to that of an uncoated bubble upon expansion. The forces acting on the microbubble wall vary as the interfacial tension changes, resulting in a nonlinear response to acoustic excitation. Using monodisperse lipidcoated microbubbles, we have studied this nonlinear behavior, including pressuredependent resonance frequency and subharmonic emissions at ultralow excitation pressures. In contrast to microbubbles, liquid perfluorocarbon nanoemulsions are incompressible and thus poorly echogenic. The nanoemulsions can be vaporized with high pressure acoustic pulses. The phase conversion is immediate and highly energetic and thus resembles an explosion on a microscale. The resultant bubbles can be used to transiently permeabilize cell membranes, thus enabling drug delivery to intracellular targets, or can be used to enhance tissue absorption of ultrasound, making ultrasoundmediated ablation more efficient. These studies provide insight into the unique nonlinear behavior of these fluidfilled particles and how they may be leveraged for exciting biomedical applications.

Tue27Mar20184:00 pmLewis Hall 101
David Meyer
Department of Mathematics
University of California — San DiegoData Science and Quantum Gravity
Data, even “big data”, is finite, and thus discrete. A common goal is to describe them as the outcome of a random process specified by a small number of parameters; doing so at least compresses the data, and at best explicates the process by which they were generated. Some important approaches include lowrank matrix factorization and multidimensional scaling, both of which reveal a geometry behind the data. Such interplay between the discrete and the continuous is familiar in theoretical and computational physics, from the definition and regularization of path integrals to numerical methods for fluid dynamics. In this talk I'll explain how recent data science results in nonmetric multidimensional scaling provide a new perspective on the HawkingMalament theorem that is the foundation of the causal set program for quantum gravity. I'll describe a new algorithm for embedding causal sets in Lorentzian manifolds motivated by this perspective. And I'll end with some speculations about possible quantum dynamics for causal sets. Familiarity with the causal set program for quantum gravity will not be assumed.

Tue03Apr20184:00 pmLewis Hall 101
Mir Emad Aghili, Vishal Baibhav, and Shrobana Ghosh
Department of Physics and Astronomy
University of MississippiPresentations by Graduate Students
"Manifoldlikeness of Causal Sets" by Mir Emad Aghili
Abstract: We study the distribution of maximalchain lengths between two elements of a causal set, and its relationship with the embeddability of the causal set in a region of flat spacetime. We start with causal sets obtained from uniformly distributed points in Minkowski space. After some general considerations we focus on the 2dimensional case and derive expressions for the expected number nk of maximal chains as a function of their length k, the most probable maximalchain length k_{0}, and the width Δ of the length distribution, as functions of the number N of causal set elements in the interval between the two points. These results, together with the results of numerical simulations of causal sets embedded in Minkowski space of various dimensionalities, show that for a given N the values of k_{0} and Δ can be used to estimate the dimensionality of a causal set embeddable in Minkowski space. Other dimension estimators are known for manifoldlike causal sets, but the length distribution also gives us a way to evaluate the embeddability of a causal set. We provide a first test of manifoldlikeness based on k_{0} and Δ, and end with a few simple examples of nk distributions for nonmanifoldlike causal sets."Systematic Errors and Energy Estimates in Binary Black Hole Ringdown" by Vishal Baibhav
Abstract: High signaltonoise ratio gravitational wave observations will enable us to measure the quasinormal frequencies of binary black hole merger remnants. In general relativity, these frequencies depend only on the remnant's mass and spin, so they can be used to test general relativity and the Kerr nature of the remnant. To carry out these tests, systematic errors must be subdominant with respect to statistical errors. I'll talk about how accurately ringdown frequencies can be extracted from stateoftheart numerical simulations from the Simulating eXtreme Spacetimes (SXS) catalog. I'll also present some results on the relative excitation of different quasinormal modes. To quantify these excitations, one must define a suitable “starting time“, e.g. by maximizing the energy content “parallel” to a quasinormal mode (as suggested by Nollert). We used Nollert's method to quantify the energy radiated in quasinormal modes for alignedspin binaries, and we produced postNewtonian inspired fits of the resulting energy estimates."Detectability of Gravitational Radiation from Superradiant Instabilities" by Shrobana Ghosh
Abstract: An incident wave, when scattered off a black hole may get amplified, at the expense of the rotational energy of the black hole. This process is known as superradiance and due to this rotating black holes can serve as particle detectors. For a massive field, the mass of the field helps in confining the field. Therefore, even an ultralight bosonic field can form a nonaxisymmetric cloud around the black hole due to repeated amplification from the black hole. This leads to emission of gravitational radiation that can be detected by groundbased or spacebased gravitational wave detectors, depending on the mass of the boson. Based on astrophysical models we show that adLIGO should see 10^{4} events in a 4 year mission for a scalar field mass of 3×10^{12} eV, while LISA will see about 10^{3} events in a 4 year mission for a scalar field mass of 10^{17} eV. In the absence of detection at a particular detector, we can rule out the corresponding mass range of the scalar field. We also look at the detectability of such events from the remnants of the merger events already seen by adLIGO at the present and future groundbased detectors. 
Sun08Apr20189:30 amRobert C. Khayat Law Center
University of Mississippi and Mississippi State University
Featuring Research talks and Poster presentations
Open to Faculty, Staff, Undergraduate students, and Graduate students
9:30 AM to 5:00 PM. 
Mon09Apr20182:45 pmLewis Hall 228
You are invited to attend Wanwei Wu's defense of his Ph.D. dissertation
at 2:45 p.m. on Monday, April 9, in 228 Lewis Hall. The title of his
dissertation is "The Beam Dynamics and Beam Related Uncertainties in the
Fermilab Muon g2 Experiment."

Tue10Apr20184:00 pmLewis Hall 101
Bruno Uchoa
Department of Physics and Astronomy
University of OklahomaTopology and Quantum Phenomena in Nodal Matter
Nodal matter describes a new metallic form where the Fermi surface collapses into sets of points or lines, and is not stabilized by Fermi pressure but by symmetries. The nontrivial quantum phenomena of those systems are described by topology, a field of mathematics that studies properties that remain invariant under continuous deformations of shapes and surfaces. In the first part of the talk I will give a general overview of the field. In the second one, I will describe a particular class of nodal materials where the Fermi surface has the shape of closed lines. I will show that interactions can drive this system into an exotic topological phase in three dimensions (3D) known as the 3D anomalous quantum Hall effect, where the system has spontaneous and topologically protected surface currents.

Tue17Apr20184:00 pmLewis Hall 101
Mukunda Acharya, Khagendra Adhikari, and Xudong Fan
Department of Physics and Astronomy
University of MississippiPresentations by Graduate Students
"Sound Speed Profiles of the Global Ocean calculated from Physical Oceanographic Data" by Mukunda Acharya
Abstract: Sound speed profiles in the global ocean are useful for modeling of sound propagation over the global oceans. This talk presents the sound speed profiles calculated from physical oceanographic data that were collected in the world ocean circulation experiment. They are data of conductivity, temperature, and pressure, taken from multiple cruises with a typical spacing of 60 km along the route of each cruise and consisting of an elaborate series of zonal (eastwest) and meridional (northsouth) coasttocoast cruises across the global oceans. Nearly 8000 sound speed profiles were mapped out that were then used to determine the dependence of sound speed minimum and depth for those minima on the longitude and latitude. Based on the characterization, practical formulas of the dependence were given."Deforming the Fredkin Spin Chain Away from its Frustrationfree Point" by Khagendra Adhikari
Abstract: The Fredkin model describes a spinhalf chain segment subject to threebody, correlatedexchange interactions and twisted boundary conditions. The model is frustrationfree, and its ground state wave function is known exactly. Its lowenergy physics is that of a strong xy ferromagnet with gapless excitations and an unusually large dynamical exponent. We study a generalized spin chain model that includes the Fredkin model as a special tuning point and otherwise interpolates between the conventional ferromagnetic and antiferromagnetic quantum Heisenberg models. We solve for the lowlying states, using exact diagonalization and densitymatrix renormalization group calculations, in order to track the properties of the system as it is tuned away from the Fredkin point. We identify a zerotemperature phase diagram with multiple transitions and unexpected ordered phases. The Fredkin ground state turns out to be particularly brittle, unstable to even infinitesimal antiferromagnetic frustration. We remark on the existence of an “antiFredkin” point at which all the contributing spin configurations have a spin structure exactly opposite to those in the Fredkin ground state."Enhancing Sound Emission by Using Subwavelength Metacavities" by Xudong Fan
Abstract: Efficient directional emission of sound waves is critical in imaging and communication, yet is held back by the inefficient emission of a small source. A change in the surrounding environment of an acoustic source can lead to enhanced emission and mode conversion. This talk will present frames of enclosing small sound sources in subwavelength metacavities to achieve sound enhancement and conversion with high efficiency. The enhancement is an analog of modifying spontaneous emission rate of a quantum source in a resonant cavity. The enhancement by a subwavelength metacavity offers a practical path toward miniaturization in applications that demand efficient emission, such as sonar, loudspeakers, or ultrasound transducers. 
Wed18Apr20183:00 pmLewis Hall 228
You are invited to attend Chandrima Chatterjee's Ph.D. dissertation defense at 3:00 PM on Monday, April 18, in 228 Lewis Hall.
The dissertation title is: "Experimental Investigation of Impurities and Their Effect on AcoustoElectric Properties of Lithium Niobate". 
Fri20Apr2018Sat21Apr20183:00 pmLewis Hall and Swayze Field (Friday) and the Field Station (Saturday)
S.T.E.M. Fest 2018 at the University of Mississippi
The physics department will participate in the 2018 S.T.E.M. Fest.
Friday, April 20, 2018
 Physics Open House. Learn why a curve ball curves or how to hit the perfect home run from the Society of Physics Students.
Lewis Hall & Swayze Field 3  5 PM.  National Center for Physical Acoustics Tours. Discover cuttingedge research on a variety of acoustic phenomena, from ultrasonic to infrasonic. NCPA, 3 PM & 4 PM.
 Hidden Figures: The movie. The 2016 blockbuster presented by the Women in Physics and the Office of Diversity and Community Engagement. Overby, 5  7:15 PM.
 Astronomy Open House: Viewings of the moon and Jupiter with the historic 1893 Grubb telescope, weather permitting.
Kennon Observatory, 8  10 PM.
Saturday, April 21, 2018
 Lightning Research at UM Field Station. Lecture on lightning and atmospheric physics by Professor Tom Marshall.
Field Station, 10:4011am.  Fun Demos at UM Field Station. Explore the physics of sound, a fire tornado, liquid nitrogen, and what happens when you lay down on a bed of nails. Field Station, 2:303:30pm.
 Physics Open House. Learn why a curve ball curves or how to hit the perfect home run from the Society of Physics Students.

Fri20Apr20188:00 pmKennon Observatory
We are offering astronomy open houses and viewings with our telescopes:
We plan to observe the Moon, nebulae and star clusters though our telescopes. All these events are weather permitting. Admission is free.
Children are welcome!See this page for the full schedule.

Tue24Apr20184:00 pmLewis Hall 101
Deidre Shoemaker
School of Physics
Georgia Institute of TechnologyNumerical Relativity in the Age of Gravitational Wave Observations
The advent of gravitational wave astronomy has created opportunities to probe strongfield gravity as we measure the merger of black holes. Numerical relativity provides the means to confront the measurements with theoretical prediction. In this talk, I'll discuss the role numerical relativity played in the observed black hole binaries by LIGO and Virgo and the future potential for unveiling strongfield gravity in both future ground and space based detectors.

Tue01May20184:00 pmLewis Hall 101
Emanuele Berti
Department of Physics and Astronomy
University of MississippiStrong Gravity and Astrophysics with Compact Binaries at the Dawn of Gravitationalwave Astronomy
Einstein's general relativity has passed all experimental verifications with flying colors, but cosmological observations and difficulties in quantizing gravity suggest that general relativity should be modified at some level. Strongfield modifications of general relativity (if they occur in nature) will in general affect the dynamics of black holes and neutron stars, with potentially observable signatures. Therefore compact objects  whether in isolation or in binary systems  are excellent astrophysical laboratories for highenergy physics and strongfield gravity. Furthermore, the gravitational radiation emitted during the inspiral and merger of compact binaries encodes important information on their astrophysical formation mechanism. I will discuss potential smoking guns of modified gravity in gravitationalwave detectors, and the theoretical and observational challenges associated with their search. I will also discuss the potential of Earth and spacebased detectors to further our understanding of the formation and evolution of compact binaries.

Sat12May201811:30 amLewis Hall, Room 104
You are invited to a buffet luncheon Honoring our 2018 Physics Graduates. It will take place in room 104 Lewis Hall from 11:30 AM to 1:00 PM.