Speaker
Kohsaku Tobioka
Description
Big Bang Nucleosynthesis (BBN) is a powerful and unique probe of new particles. In particular, if hadrons are injected by a new particle during BBN, the measurement of helium-4 can constrain the lifetime of that particle to be significantly shorter than the BBN time scale. In this talk, I will discuss new developments that include previously missing effects, such as scattering processes involving KL and secondary hadrons. I will then apply these results to the heavy QCD axion and obtain the first robust BBN bounds. This talk is based on arXiv:2510.23695.
