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Speaker: Jorge Lopez, University of Texas El Paso

Title: Italian delicacies served up in a neutron star crust.

Abstract: The study of heavy ion reactions has taught us that nuclear matter has liquid and gaseous phases, phase changes, critical behavior, and many rich phenomena. Here a summary of theoretical efforts leading to the understanding of the thermodynamics of nuclear matter will be presented, including recent ones that study possible “pasta” like structures of neutron star crusts.
Refs:
  *   , J.A. Muñoz and J.A. López, Dynamics 2024, 4(1), 157-169.
  *   , J.A. López, C.O. Dorso, and G. Frank, Front. Phys. 2021, 16 (2), 24301. 
  *   , World Scientific.
Host: Benjamin Fregoso

Speaker: Nayana Shah, Washington University in St. Louis

Title: Reimagining a complex quantum system: turning fermions to bosons, bosons to fermions

Abstract: To explore and understand complex interacting systems, often the first step is to pose probing questions, both theoretically and experimentally, and to identify the relevant degrees of freedom for the conditions of interest. This then allows one to construct a model for the system that captures the interplay of those chosen variables. But this model may still not be amenable to theoretical analysis. One of the elegant ways to proceed is to seek a change of variables that transforms the model into a simplified form and at the same time advances the quest for identifying the emergent degrees of freedom at play. Transforming fermion fields to boson fields has been one such method of choice in low-dimensional strongly correlated quantum systems for the last five decades. Bosonization is a non-trivial transformation that in the case of the celebrated Luttinger model, transforms interacting one-dimensional fermions into free bosons and reveals the emergence of spin-charge separation. Another key paradigm for strong-coupling physics comes from the Kondo model for a localized impurity spin interacting with a conduction electron sea. Here too bosonization helps, and with additional unitary transformations leads to a solvable point. At this so-called Toulouse point, the reorganized bosons can now be transformed back to fermions to obtain a resonant-level model.  After reviewing these ideas I will talk about work done over the last decade to put forth and establish a consistent way of implementing these transformations. To do so, I will share the story of its genesis in our discovery of inconsistencies and symmetry violations as we resolved a non-equilibrium transport puzzle. I will then conclude with the insights we have gained from our in-depth analysis of the multi-channel Kondo model using solvable points and renormalization group methods to compare the old/conventional and new/consistent ways of implementing the "bosonization-debosonization" program.

Host: Benjamin Fregoso

Speaker: Maxim Dzero, �鶹ӰԺ

Title: Spontaneous synchronization: from fireflies to superconductors

Abstract: The tendency to synchronize is one of the most ubiquitous and at the same time mysterious drives in all of nature. In the first part of my talk, I will show how the work of scientists from various disciplines came to the intriguing realization that the study of synchrony could deepen our understanding of not only certain aspects of human behavior or enormous congregations of fireflies blinking on and off in complete unison, but also the collectively synchronous behavior of 10²³ electrons in advanced quantum materials. I will then proceed and discuss an example of how the tendency to spontaneously synchronize emerges in conventional superconductors which are driven out of equilibrium by an external electromagnetic radiation. Finally, I will discuss how this phenomenon of spontaneous synchronization in superconductors can be probed experimentally.

Host: Physics department  

Speaker: Veronica Dexheimer,  �鶹ӰԺ 

Title: Using Neutron Stars to Reveal the Secrets of Dense Matte

Abstract: Matter inside neutron stars and their mergers can reach densities of more than 10 times normal nuclear density. In such extreme environments, new particles and phases of matter appear, as well as different interactions become important. In this talk, I review old and new ways to use neutron star observable to learn about dense matter, comment on what we know and what we expect to discover within the next years concerning dense matter, and provide an overview of modern ways to build and share dense matter descriptions (usually referred to as equations of state).

Host: Physics department

Speaker: Melanie Good,  University of Pittsburgh

Title: Student Perceptions of Physics

Abstract: Understanding the subjective perspectives of physics students can help inform physics instructors as they design their course structure and pedagogical strategies to promote a positive learning environment.  I will discuss several strands of research I have conducted that shed light on these issues.  Using survey data collected over multiple semesters, I will discuss how introductory STEM students perceive problem-solving and course demands in physics. I will also share an investigation into the beliefs of non-STEM majors about science vs. pseudoscience in physics.  Finally, I will conclude with a qualitative analysis, based on open-ended survey responses, of graduate TA perspectives on introductory physics problems.

Host: Peter Tandy

Speaker: Jonathan Selinger,  �鶹ӰԺ

Title: Reformulation of elasticity theory for liquid crystals and lipid membranes.

Abstract: In this talk, we suggest mathematical reformulations of two classic concepts in the theory of soft matter: the Oseen-Frank free energy for nematic liquid crystals and the Helfrich free energy for lipid membranes. For nematic liquid crystals, the free energy becomes the sum of squares of four modes (splay, twist, bend, and a fourth bulk mode related to saddle-splay). For lipid membranes, it becomes the sum of squares of two modes (the sum and difference of principal curvatures).  In each case, the reformulation shows how molecular shape and ordering can induce director gradients or membrane curvature. Hence, it provides a unified framework to understand the wide variety of modulated phases in liquid crystals and curved microstructures in lipid membranes.

Host: Physics department