Title: Search for Light Sterile Neutrinos with Two Neutrino Beams at MicroBooNE

Abstract: The Standard Model of particle physics predicts only three flavors of neutrinos: νe, νµ and ντ. However, anomalous measurements from the Liquid Scintillator Neutrino Detector (LSND) and Mini-Booster Neutrino Experiment (MiniBooNE), as well as from Gallium experiments, could all be explained by the existence of a fourth neutrino flavor. This neutrino would not interact weakly and thus is described as a "sterile" neutrino.

We use data collected in the MicroBooNE Liquid Argon Time Projection Chamber (LArTPC) to exclude the single-sterile-neutrino interpretation of the MiniBooNE and LSND anomalies at the 95% confidence level and rule out a notable portion of the parameter space that could explain the Gallium anomaly. This measurement is facilitated by the use of two neutrino beams withdifferent intrinsic νe fractions, breaking the degeneracy between νµ → νe appearance and νe → νe disappearance. Furthermore, the LArTPC detector technology enables a high-purity, high-efficiency inclusive νe charged current selection through its sub-cm level position reconstruction and MeV-scale energy reconstruction. We find no evidence for nonstandard neutrino oscillations from measurements of νµ → νe flavor transition and νe disappearance

Join us for a showcase of new Social Theory affiliate faculty. Featuring:

• Maria Diaz, History
• Virginia Downing, Educational Leadership Studies
• Emine Seda Kayim, Architecture
• Rachel Lautenschlager, Sociology
• Abigail Mack, Anthropology

Title: Topological Electron Crystals in a Mass-Asymmetric Electron-Hole Bilayer

Abstract: Moiré superlattices have become a standard route to realizing correlated and crystalline electronic phases in two-dimensional materials by quenching kinetic energy. In this talk, I will describe a different mechanism for generating topological electron crystals based on interlayer charge transfer rather than moiré engineering.

Our platform is a heterostructure consisting of bilayer graphene and a Mott insulator. Charge transfer between the layers leads to a charge-neutral, mass-asymmetric electron-hole bilayer, where itinerant carriers in bilayer graphene are attractively coupled to heavy, localized carriers in a flat Hubbard band. In the dilute heavy-fermion limit, this system supports a remarkably rich set of electron crystal phases, including triangular, honeycomb, and Kagome crystals.

A key result is that the nonlocal nature of bilayer graphene wave functions strongly modifies the real-space charge profile, which in turn stabilizes these unconventional crystalline orders at intermediate interlayer attraction. The resulting phases carry distinct Hall responses and topological characteristics, opening a route to crystalline topology beyond the conventional moiré setting. I will present the phase diagram, explain the role of quantum geometry, and discuss possible experimental platforms.