A positive pion collides with a neutron and the following interaction is observed:
π++n→K++Σ0 \pi^+ + \text{n} \to \text{K}^+ + \Sigma^0 π++n→K++Σ0Σ0\Sigma^0Σ0 is a neutral sigma particle with a strangeness of −1-1−1.
The interaction can be used to deduce the classifications of the Σ0\Sigma^0Σ0.
Identify the classifications of each particle by completing the table below. Place a tick (✓\checkmark✓) in the appropriate boxes for each particle.
| Particle | Baryon | Hadron | Lepton | Meson |
|---|---|---|---|---|
| π+\pi^+π+ | ||||
| n\text{n}n | ||||
| K+\text{K}^+K+ | ||||
| Σ0\Sigma^0Σ0 |
A conservation rule predicts that the following interaction cannot occur:
π++n→Kˉ0+Σ+ \pi^+ + \text{n} \to \bar{\text{K}}^0 + \Sigma^+ π++n→Kˉ0+Σ+State the conservation rule and explain your answer.
One way in which neutral pion mesons decay is:
π0→e−+e++γ \pi^0 \to \text{e}^- + \text{e}^+ + \gamma π0→e−+e++γCompare the rest energies of the particles involved in this decay.
The decay of the neutral pion meson leads to the production of further gamma photons. Explain why.
The concept of quarks was first proposed in 1964, but experimental confirmation of the top quark was not achieved until 1995. Suggest why progress in experimental particle physics to confirm such theoretical predictions can be so slow.
50 exam-style questions on AQA A Level Physics Particles, covering Constituents of the atom, Stable and unstable nuclei, Particles, antiparticles and photons, Particle interactions, Classification of particles, Quarks and antiquarks, and Applications of conservation laws. Each one has a worked solution and a mark scheme showing where the marks go.