Weakly decaying negative particles may live long enough to come to rest in matter and be captured by a nucleus. Consider the simplest case of the capture by a proton. 

(a) Evaluate the Bohr radius for the μ ̅ p system (muonium), the π ̅ p system (pionium), the K ̅ p system (kaonium) and the p̅p system (antiprotonium).

(b) Calculate the energy released in the capture of an electron at rest into the ground state by a proton.