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Particle Physics Questions

Q6.

 

(a) The Σ+ particle is a baryon with strangeness –1.

(i) How many quarks does the Σ+ particle contain? Three

(1 mark)

(ii) How many of the quarks are strange? One

(1 mark)

(b) The Σ+ decays in the following reaction

Σ+ → π+ + n

(i) State two quantities that are conserved in this reaction.

Charge Baryon number Lepton number Mass Energy Momentum Maximum 2 marks

(2 marks)

(ii) State a quantity that is not conserved in this reaction.

Strangeness

(1 mark)

(iii) What interaction is responsible for this reaction?

Weak Interaction (must be because strangeness isn't conserved)

(1 mark)

(iv) Into what particle will the neutron formed in this reaction eventually decay?

proton (see proton/neutron stability)

(1 mark)

(Total 7 marks)