This question is about particles and interactions.
When a free neutron decays to a proton, an electron is one of the decay products.
(i) State the name of the exchange particle and the interaction involved in this decay.
(ii) The interaction and the exchange particle in (a)(i) may arise when a quark decays. Describe the change in the quark structure of the neutron.
▶️Answer/Explanation
Markscheme
(i) W/intermediate vector boson and weak; (both needed for mark)
(ii) d in neutron changes to u (in proton);
This question is about a K meson decay.
The positive kaon K+ has a strangeness of +1. It can decay through the interaction
K+ → μ+ + νμ.
Charge, energy and momentum are conserved in this decay.
a.State the quark structure of the K+.[1]
(i) conserved.
(ii) not conserved.[2]
▶️Answer/Explanation
Markscheme
a.
\(u\overline s \);
(i) baryon/lepton number / colour;
(ii) strangeness;