Hadrons and leptonsAQA A-Level Physics: Mind map

Exam questions on Hadrons and leptons

1. In a high-energy collision experiment, protons are fired at protons in a liquid hydrogen target. The physicists check each proposed reaction against the conservation laws before searching for it in the data.
   Explain why the reaction p + p → p + π⁺ cannot occur.2 marks
2. Cosmic rays striking the upper atmosphere produce muons, some of which reach ground-level detectors, where they are observed to decay. A negative muon decays into an electron and two other leptons.
   The decay μ⁻ → e⁻ + γ is never observed. Use lepton numbers to explain why.2 marks
3. Physicists study the decays of mesons and baryons produced when high-energy protons strike a target. They record the kaon decay K⁺ → π⁺ + π⁰ and the decay of free neutrons.
   Show that charge and baryon number are both conserved in the decay K⁺ → π⁺ + π⁰.3 marks