Speaker
Description
Majoron-like particle $J$ in the mass range between 1MeV to 10 GeV, which dominantly decays into the standard model (SM) neutrinos, can be constrained from the big-bang nucleosynthesis (BBN). For majoron lifetime ($\tau_J$) smaller than 1sec, the injected neutrinos from the majoron decay heat up the background plasma and it results in the deficit of Helium-4 abundance and enhancement of Deuterium (D) abundance. For $\tau_J$ larger than 1sec, the injected neutrinos enhance the conversion rate of $p\to n$ which results in the enhancement of Helium-4 and D abundance. We found that in both cases, the constraint from the measurement of D is the strongest. We also estimate the $\Delta N_{\rm eff}$ constraint on the majoron parameter space and compare it with the BBN bounds, obtained from our analysis.
