UC San Diego

We are developing a code to self--consistently treat beyond--standard--model physics in the early universe. This work details the calculations done with regards to the epochs of weak decoupling, weak freeze--out, big bang nucleosynthesis, recombination, and includes exploratory work on dilution and electron--positron annihilation. We assess the predictions made by the standard model, and investigate how new physics in the neutrino sector may alter or preserve those predictions. Throughout this work, we use natural units : hbar=c=k_b=1