2.2 Classification of Particles

A pion can decay to produce two leptons.

Which of the following reactions is possible?

In an arrangement known as a ‘baryon decuplet’, baryons are organised along horizontal and diagonal axes, as shown in the diagram below.

What quantities are depicted on the horizontal and diagonal axes?

The baryon, composed of the quark combination , is produced through the strong interaction between a  meson and a neutron.

What is the quark composition of particle X?

Particles can be organised in a plot known as the ‘eightfold way’, as shown in the diagram below. Plotting the particles in this way helps scientists to identify symmetries between different particles.

Six baryons and their quark compositions are shown at the vertices of a hexagon. The centre of the hexagon represents two baryons with the same quark composition.

Vertices are linked by horizontal axes representing strangeness, S, and diagonal axes representing charge, q. Some of the quark compositions are missing from the diagram.

What are the quark compositions of Σ⁺, Σ^–, Ξ⁰ and Ξ^–?

	Σ+	Σ–	Ξ0	Ξ–
A
B
C
D

In a reaction, four meson particles were made. Two of them were electrically neutral; while of the other two, one had a positive charge and the other had a strangeness of +1.

Three of the quark combinations were as follows:  ,  & 

Which of the following could not be the combination of the last particle?

The K^– is an example of a meson with strangeness –1.

Which of the following decays of the K^– particle is most likely?

A collision between two baryons occurs creating two mesons, this is shown below:

What are the particles involved in this reaction?

	1	2	3	4
A	neutron	antineutron
B	proton	antiproton
C	neutron	antineutron
D	proton	antiproton

Which row in the table, A to D, includes a valid particle for every column?

A collision between particles creates 4 mesons. Two of the mesons are determined to have the quark combinations  and . 

The overall charge and strangeness of the 4 mesons is zero.

What are possible quark combinations of the other two mesons?

Which of the following statements is not correct?

The K⁺ meson has a strangeness of +1.

What is the quark structure for a K⁺ meson?

Which of the following statements is true?

A protactinium nucleus decays into a nucleus of Th–230, a beta-plus particle and particle X.

What is a property of particle X?

Which row in the table gives the correct quark combination for the particle?

	particle	category	quark combination
A	proton	baryon
B	positive pion	meson
C	neutron	meson
D	negative pion	meson

A possible decay of the K⁺ is shown in the following equation

What could particle X be?

Some particles are made up of a combination of three quarks.

Which particle would not have a charge of either +1.6 × 10^–19 C or zero?

The composition of four different hadrons are shown in the diagram below.

One of the hadrons is a Σ⁰ particle. It has a charge of 0, and a strangeness of –1.

Which of the following hadrons, A to D, could the Σ⁰ particle be?

Which of the following rows, A to D, correctly describes the properties of strange particles and strangeness?