Updated Big Bang Nucleosynthesis Bounds on Long-lived Particles from Dark Sectors

As electromagnetic showers may alter the abundance of Helium, Lithium, and Deuterium, we can place severe constraints on the lifetime and amount of electromagnetic energy injected by long-lived particles. Considering up-to-date measurements of the light element abundances that point to $Y_p=0.245\pm 0.003$, $(\mathrm{D}\mathrm{/}\mathrm{H})=(2.527\pm 0.03)\times {10}^{-5}$, and the baryon-to-photon ratio obtained from the Cosmic Microwave Background data, $\eta =6.104\times {10}^{-10}$, we derive upper limits on the fraction of electromagnetic energy produced by long-lived particles. Our findings apply to decaying dark matter models, long-lived gravitinos, and other non-thermal processes that occurred in the early universe between ${10}^2-{10}^{10}$ seconds.