Quarks and Leptons Flashcards
What are cosmic rays?
High energy particles that travel through space from the stars. including the sun.
What do cosmic rays do?
They collide with gas atoms in the atmosphere, creating showers of particles and antiparticles which can be detected at ground level.
What does a kaon decay into?
Pions, or muon and antineutrino, or antimuon and neutrino.
What does a charged pion decay into?
A muon and an antineutrino, or antimuon and neutrino.π 0 meson decays into high energy photons.
What is a muon, and what does it decay into?
It is a heavy electron, it decays into an electron and an anitneutrino and an muon neutrino.
How are kaons produced?
They’re produced in two’s through the strong interaction.
How do kaons decay?
They decay through the weak interaction. These properties lead them to being called strange particles.
What are hadrons?
Particles/antiparticles that interact through the strong force - E.G - protons, neutrons, pi mesons and k mesons
What are leptons?
Particles/antiparticles which don’t interact through the strong interaction. E.G: electrons, muons and neutrinos.
What do leptons interact through?
mostly the weak interaction but also a bit through the gravitational interaction and electromagnetic interaction if charged.
What can hadrons interact through?
All four fundamental interactions. They interact through the electromagnetic interaction if charged.
Apart from hadrons, which is stable, what do hadrons tend to decay through?
The weak interaction
What are baryons?
Protons and all other hadrons that decay into protons, either directly or indirectly. They are made up of 3 quarks.
What are mesons?
Hadrons that don’t include protons in their decay products. So kaons and pions aren’t baryons. Made up of quark antiquark.
What do leptons produce when they interact?
Hadrons.
Name some leptons
electron, muon, neutrino and corresponding antiparticles.
In an interaction between a lepton and a hadron, what changes into what?
A neutron/neutrino can change into a lepton.
What happens in muon decay?
A muon changes into a muon neutrino, and an electron is created to conserve charge. A corresponding antineutrino is created to conserve lepton number.
What do strange particles decay through?
The weak interaction.
When is strangeness always conserved? When can it change?
During the strong interaction it is always conserved. In the weak interaction it can change by 0, +1 or -1.
What is the quark combination for a meson?
Quark, antiquark. π0 meson can be any quark - corresponding antiquark combination.
What is the quark composition for baryons and antibaryons?
Three quarks for a baryon and three anti quarks for an antibaryon.
What is the quark composition for a proton?
uud
What is quark composition for a neutron?
udd
What is the quark change in beta minus decay and beta plus decay?
Beta minus: down turns into an up quark.
beta plus: Up turns into a down quark.
What is always conserved in particle interactions?
Energy, charge, lepton number, baryon number.
what values are assigned for leptons, baryons and strange particles
Leptons - +1, anti leptons - (-1)
Baryons - +1, antibaryons - (-1)
Strange particle - (-1), anti strange particle - (+1)
What are leptons?
They are fundamental particles that don’t interact through the strong force.
