Physics (AS & A Level) · May / June 2018 · Paper 12 · Question 40

A neutron is composed of one up (u) quark and two down (d) quarks. When the neutron decays to a proton, there is β-emission. What is the change in the quark structure of the neutron due to the β-emission? (The symbol for a neutrino is νe and for an antineutrino is $\bar{\nu}_e$.)

1. Ad → u + β⁻ + νe
2. Bd → u + β⁻ + $\bar{\nu}_e$
3. Cu → d + β⁺ + νe
4. Du → d + β⁺ + $\bar{\nu}_e$

As printed in the paper