The Vanderbilt Initiative for Gravity, Waves, and Fluids is an interdisciplinary research venture providing mathematicians, physicists, and astrophysicists with the resources and space to connect and collaboratively work on problems of outstanding scientific merit, such as:

• General relativity: theoretical, mathematical, numerical, or experimental, including, but not restricted to, black holes, gravitational radiation, and multimessenger astrophysics.
• Fluid mechanics: theoretical, mathematical, numerical, or experimental, including, but not restricted to, relativistic fluids far from equilibrium.
• Evolution of partial differential equations related to fluids and gravity, including, but not restricted to, the geometric analysis of waves and fluids.
• The physics and mathematics of neutron star mergers and high-energy nuclear collisions.

VandyGRAF Seminar Series

All VandyGRAF talks will take place in the Chapel in the 17th&Horton building, unless indicated below.

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Berndt Mueller, Duke University

October 18, 12:00 pm - 1:30 pm

Towards entanglement and thermalization in QCD

Abstract: The entanglement entropy of a small subsystem of an isolated interacting quantum system indicate whether the subsystem can be interpreted as a “thermal” system. This property is conjectured to underpin the thermal model that has been so successful in describing the final state of relativistic heavy ion collisions. Here we report studies of the entanglement entropy of Hamiltonian SU(2) lattice gauge theory in 2+1 dimensions on linear plaquette chains as a toy model for QCD. We find that the entanglement entropies of both ground and excited states follow Page curves and the transition from the area law for the ground state to the volume law for highly excited states as a function of subsystem size is governed by a universal crossover function. Quantum many-body scars in the middle of the spectrum, which are present in the electric flux truncated Hilbert space, where the gauge theory can be mapped onto an Ising model, disappear when higher electric field representations are included in the Hilbert space basis. This suggests that small subsystems in the continuum SU(2) gauge theory truly behaves as “thermal” systems.

Derek Davis, California Institute of Technology

October 25, 12:00 pm - 1:30 pm

Decoding LIGO detector data for high-precision gravitational-wave astronomy

Abstract: Gravitational-wave detectors, such as the Laser Interferometer Gravitational-wave Observatory (LIGO), have changed how we observe our universe by detecting gravitational waves from merging black holes and neutron stars. However, finding these signals requires highly sensitive detectors and careful procedures to analyze the recorded data. As the detection of gravitational-wave events becomes an everyday occurrence, the demand for precision in our gravitational-wave data analysis techniques continues to grow. One of the main roadblocks to further improvements is the presence of continually evolving instrumental artifacts in our data. In this talk, I will discuss my ongoing work to decode the complexities of gravitational-wave data and improve the robustness of astrophysical analyses. This includes direct investigations of the nature of instrumental artifacts, how these artifacts might mimic gravitational-wave signals or impact analysis of real events, and how we can use multiple analysis approaches to separate exciting new physics from everyday noise. 

Peter Olver, University of Minnesota

November 8, 12:00 pm - 1:30 pm

Two New Developments for Noether’s Two Theorems

Abstract: In the first part, I start by recalling the two well-known classes of partial differential equations that admit infinite hierarchies of higher order generalized symmetries: 1) linear and linearizable systems that admit a nontrivial point symmetry group; 2) integrable nonlinear equations such as Korteweg–de Vries, nonlinear Schrödinger, and Burgers’. I will then introduce a new general class: 3) underdetermined systems of partial differential equations that admit an infinite-dimensional symmetry algebra depending on one or more arbitrary functions of the independent variables. An important subclass of the latter are the underdetermined Euler–Lagrange equations arising from a variational principle that admits an infinite-dimensional variational symmetry algebra depending on one or more arbitrary functions of the independent variables. According to Noether’s Second Theorem, the associated Euler–Lagrange equations satisfy Noether dependencies; examples include general relativity, electromagnetism, and parameter-independent variational principles.

Noether’s First Theorem relates strictly invariant variational problems and conservation laws of their Euler–Lagrange equations.  The Noether correspondence was extended by her student Bessel-Hagen to divergence invariant variational problems. In the second part of this talk, I highlight the role of Lie algebra cohomology in the classification of the latter, and conclude with some provocative remarks on the role of invariant variational problems in fundamental physics.

Mainak Mukhopadhyay, Pennsylvania State University

November 15, 12:00 pm - 1:30 pm

James Dent, Sam Houston State University

November 22, 12:00 pm - 1:30 pm

Khwahish Kushwah, Universidade Federal Fluminense

December 6, 12:00 pm - 1:30 pm

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