Theory Seminar (High Energy/Cosmology) |
Events During the Week of February 1st through February 8th, 2026
Monday, February 2nd, 2026
- Freezing-in the Axiverse
- Time: 1:00 pm - 2:30 pm
- Place: Chamberlin 5280
- Speaker: Christopher Dessert, Flatiron Inst., New York
- Abstract: The presence of light axions in the infrared is a generic feature of many ultraviolet (UV) scenarios, including string theory, with the number of such axions N naturally O(10-100). Even when these axions interact very weakly with the Standard Model (SM), the presence of N light axions is constrained by the number of relativistic degrees of freedom N_eff. Adopting an effective field theory approach, I compute the freeze-in abundance of Axiverse axions. Under generic assumptions for the structure of the axion-Standard Model couplings, the predicted N_eff may be already excluded by Planck or probed by ongoing cosmic microwave background surveys like Simons Observatory. Event recording:
- Host: Joshua Foster
Tuesday, February 3rd, 2026
- No events scheduled
Wednesday, February 4th, 2026
- No events scheduled
Thursday, February 5th, 2026
- No events scheduled
Friday, February 6th, 2026
- No events scheduled