Solving the Lithium Problem with a simple model

par M. Vivian Poulin

mardi 18 nov. 2014, 14:30 → 15:30 Europe/Paris

Salle Semnoz (LAPTh)

The Big Bang Nucleosynthesis (BBN) is a huge success of the « standard model of cosmology » but for the prediction of primordial Lithium abundance. According to previous studies motivated by new models of particle physics, it is very challenging to solve this Lithium problem by injecting energy at the BBN epoch (at least in EM channel), due to extreme agreement between prediction and measurements of the other primordial abundances: any model able to solve the problem for the lithium would change the abundances and thus create a problem for other nuclei, or be ruled out by too big change of the CMB spectrum. However, thanks to a better treatment of the photon spectrum available to photodissociate the nuclei, we found a loophole to the previous studies enabling us, using a very simple model, to solve the problem. I will review the basics of thermal and non-thermal BBN and present the results of our study (forthcoming paper, not yet available on the arxiv) invoking two models : A « proof of principle » one and an actual, albeit simple, particle physics model, the sterile neutrino.