A lambda baryon ${\Lambda ^0}$ is composed of the three quarks uds. Show that the charge is 0 and the strangeness is $- 1$.

Discuss, with reference to strangeness and baryon number, why this proposal is feasible.

Strangeness:

Baryon number:

Another interaction is

$${\Lambda ^0} \to p + {\pi ^ - }$$

In this interaction strangeness is found not to be conserved. Deduce the nature of this interaction.

$+ \frac{2}{3} - \frac{1}{3} - \frac{1}{3} = 0$ for charge;

any particle containing a strange quark has strangeness of $- 1$;

strangeness:

the $p$ has a strangeness of 0;

the ${K^ - }$ particle has a strangeness of $- 1$;

baryon number:

lambda and protons are baryons each having a baryon number of $+ 1$;

the ${K^ - }$ meson has a baryon number of 0;

only during the weak interaction strangeness is not conserved (therefore it is a weak interaction);

Well answered question, often very clearly and straightforward; some, even better candidates made mistakes in calculation in (b)(iii). SL candidates showed more difficulty with (b)(iii), often using an incorrect approach.

Well answered question, often very clearly and straightforward; some, even better candidates made mistakes in calculation in (b)(iii). SL candidates showed more difficulty with (b)(iii), often using an incorrect approach.

Well answered question, often very clearly and straightforward; some, even better candidates made mistakes in calculation in (b)(iii). SL candidates showed more difficulty with (b)(iii), often using an incorrect approach.