Hadrons and leptonsAQA A-Level Physics: Flashcards
What these 12 flashcards ask
- What is a hadron?
- Name the two classes of hadron.
- Give examples of baryons and mesons.
- What is the baryon number of a baryon, an antibaryon and a meson?
- Which baryon is stable?
- What is the pion's role in the strong interaction?
- Name a kaon decay.
- Name the leptons you need to know.
- What are the lepton numbers of an electron and a positron?
- Which lepton numbers are conserved?
- Write the muon decay equation.
- Why does particle physics need large teams?
Exam questions on Hadrons and leptons
- 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
- 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
- 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
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).