Description
After a brief motivation I will present RBC/UKQCD's $b$-physics program. In the first half of the talk, I will focus on our recent results for neutral meson mixing obtained from purely domain wall fermion simulations and outline our ongoing efforts to improve upon this result. In the second half, I will focus on semi-leptonic $B_{(s)}$ decays where we use the non-perturbatively tuned relativistic heavy quark action for the bottom quark and domain wall fermions for all other quark flavours.