Events at Physics |
Events on Monday, April 20th, 2026
- Plasma Physics (Physics/ECE/NE 922) Seminar
- Effects of magnetic geometry and neutrals in gyrokinetic simulations of magnetized boundary plasmas
- Time: 12:00 pm - 1:00 pm
- Place: Engineering Hall - 1227
- Speaker: Dr. Tess Bernard, General Atomics
- Abstract: Successful fusion pilot plant (FPP) design hinges upon the ability to predict and control exhaust conditions to maximize the lifetime of plasma-facing components. This work describes a pathway toward high-fidelity, first-principles simulations with predictive capabilities for plasma particle fueling and detachment. It presents the coupling of a continuum full-f gyrokinetic turbulence model with atomic neutral models, using the Gkeyll code. To investigate how neutral interactions and plasma shaping fundamentally affect edge turbulent transport, we carry out simulations of DIII-D inner-wall-limited (IWL) plasmas. We specifically consider negative triangularity (NT) plasmas, which exhibit robust confinement properties without the presence of disruptive edge localized modes (ELMs). Results demonstrate good agreement with experimental data, with neutral interactions providing important particle fueling and heat loss channels. Our analysis reveals key differences in the shear flow and turbulent fluctuations that contribute to improved confinement properties in NT.
- Host: Stephanie J. Diem
- Theory Seminar (High Energy/Cosmology)
- A data-driven prediction for the primordial deuterium abundance
- Time: 1:00 pm - 2:30 pm
- Place: Chamberlin 5280
- Speaker: Hongwan Liu, Boston U.
- Abstract: The primordial deuterium abundance D/H from Big Bang Nucleosynthesis (BBN) is one of the most powerful probes of ΛCDM cosmology and its extensions. I will present a novel, fully data-driven method for predicting D/H using Gaussian processes, validated with Monte Carlo tests that confirm negligible bias and accurate coverage of the resulting uncertainties. Applying the same Monte Carlo framework to polynomial fitting methods commonly used in the literature, we find that these systematically overestimate D/H. Assuming baryon abundances from CMB measurements, our predictions are approximately 2σ discrepant with observations of the primordial D/H. Event recording:
- Host: Joshua Foster
- Graduate Program Event
- A search for dark matter recoiling from the standard model Higgs boson using the CMS experiment
- Time: 1:00 pm - 3:00 pm
- Place: Chamberlin 3290 (NOTE UPDATED LOCATION)
- Speaker: Shivani Lomte
- Abstract: Astrophysical evidence supports the existence of dark matter based on its gravitational interaction. Astrophysical evidence also points to that dark matter interacts at most very weakly with the standard model particles. The only purely weakly interacting particles in the standard model are neutrinos, which have too low a mass to be the dark matter candidates. Therefore, there is compelling motivation for physics beyond the standard model which contains weakly interacting massive particles. Many beyond the standard model theories predict the existence of dark matter particle candidates that can be produced and detected at high energy colliders, driving experimental searches at the CERN LHC. This thesis presents a search for dark matter particles produced in association with a Higgs boson in proton-proton collisions at 13 TeV. The data, collected with the CMS detector at the LHC, correspond to an integrated luminosity of 101 /fb. Higgs decay to a bottom quark-antiquark pair is reconstructed to identify events of interest. The analysis is performed in exclusive categories targeting both Lorentz-boosted (merged) and resolved b-pair topologies, covering a wide range of Higgs boson transverse momentum. This analysis looks for statistically significant deviations from the standard model predictions, either enhancements in specific kinematic regions or a bump in the b-pair invariant mass distribution. The observed data agree with the standard model background predictions. Constraints are placed on dark matter models predicting new particles or interactions, such as those in the simplified frameworks of baryonic-Z' and 2HDM+a. A statistical combination is made with a previous search using data collected in 2016 and corresponding to an integrated luminosity of 35.9 /fb. Upper limits at 95% confidence level are set on the production cross section for these models. These results improve upon the previously existing LHC limits owing to the larger integrated luminosity and improved identification of h-->bb decay. Potential improvements from an ongoing CMS search using the Run-3 data are discussed, along with the future prospects at a high energy muon collider.
- Host: Sridhara Dasu