Classification of particles Flashcards – AQA A-level Physics (7408)

What are hadrons?

Particles that experience the strong interaction.

What are the two classes of hadrons?

Baryons and mesons.

How are protons, neutrons, antiprotons and antineutrons classified?

Protons and neutrons are baryons; antiprotons and antineutrons are their corresponding antibaryons.

What two types of particle are examples of mesons?

Pions and kaons.

Which baryon is stable?

The proton is the only stable baryon.

What do free baryons other than protons eventually decay into?

Particles that include a proton, subject to conservation laws.

What baryon number is assigned to each of the three particle categories: baryons, antibaryons, and particles that are neither?

• Baryons: $+1$
• Antibaryons: $-1$
• Neither: $0$

What does conservation of baryon number require in a particle interaction or decay?

The total baryon number before the process equals the total afterwards.

Which exchange particle mediates the strong nuclear force that binds protons and neutrons in nuclei?

The pion.

Which four particles are leptons?

The electron, muon, electron neutrino and muon neutrino.

Which of the electron, muon and their neutrinos are electrically charged, and which are neutral?

The electron and muon are charged; their neutrinos are neutral.

What corresponding antiparticle does each lepton have?

Each lepton has its own corresponding antiparticle.

What can an unstable muon decay into?

An electron accompanied by neutrinos.

What work do teams of scientists and engineers carry out in particle physics?

They develop experiments, collect and analyse data, and assess results.

What does collaboration bring together in particle physics?

Different areas of expertise.

How does collaboration help validate new particle-physics knowledge?

It enables results to be checked, providing evidence for validation.