High Energy Physics Seminar

The presence of multiple light axions in the infrared is a generic feature of many ultraviolet (UV) scenarios, including string theory. The number of such axions N can naturally be O(10-100). Even in the scenario where these axions interact very weakly with the Standard Model (SM), the presence of N light axions poses a challenge to the stringent constraint on the number of relativistic degrees of freedom N_eff. I will parametrize the interaction of N axions with the Standard Model (SM) to quantify the contribution to N_eff, paying particular attention to the possible flavor structures of the axion-SM fermion couplings. For various such choices, I will identify the discovery space for current and future cosmic microwave background surveys.

The talk is in 469 Lauritsen.

Contact [email protected] for Zoom link.