Particles and Waves: 1 - The Standard Model Flashcards
What is the standard model?
The Standard Model is a model of fundamental particles and interactions.
Where does the evidence for the existence of quarks come from?
The evidence for the existence of quarks comes from high-energy collisions between electrons and nucleons, carried out in particle accelerators.
What is a nucleon?
A proton or a neutron.
What are hadrons?
Composite particles that are made up of quarks.
How many types of hadron are there and what are they called?
- Baryons and Mesons.
What are baryons?
Baryons are like protons and neutrons and are made up of 3 quarks.
What are Mesons made up of?
Mesons are made up of quark - antiquark pairs so they are very unstable, e.g. a pion (π+) is made of an up quark and a down anti - quark.
What are examples of Mesons?
A pion (π+).
What are examples of Baryons?
Protons and Neutrons.
Are Mesons unstable?
Yes they are very unstable.
What are protons made of?
2 up and 1 down quarks.
What are neutrons made of?
2 down and 1 up quarks.
What is this (π+) pion made of?
1 up and 1 down anti - quark.
What are leptons?
Leptons are the fundamental particles, i.e. they can’t be split into anything smaller.
What are the 1st generation leptons?
The electron.
What are the 2nd generation leptons?
The muon.
What are the 3rd generation leptons?
The tau.
What do all leptons have in common?
They are negatively charged.
What is the charge of a neutrino and what does this mean for the neutrino?
Neutrinos have no charge,because of this they never interact with any other particles.
How were neutrinos initially discovered?
Neutrinos were initially discovered in radioactive beta decay experiments.
In beta decay what does a neutron decay into, why must another particle be admitted and what is the other particle that is admitted.
In beta decay, a neutron decays into a proton and an electron. In order for mass charge and energy to be conserved another particle must be admitted. This particle is the neutrino.
What is the equation of the beta decay of a neutron?
A neutron
->
proton + electron + neutrino
What are facts about the Strong (nuclear) Force?
- Electrostatic theory predicts that the protons in the nucleus should fly apart. This does not happen so there must be another force and holds the nucleons together.
- Extremely short range force that holds particle of the same charge together - holds quarks together to form hadrons. (HOLDS TOGETHER PARTICLES IN THE NUCLEUS)
What is the exchange particle/force carrier for the strong (nuclear force)?
The gluon because they glue particles together.
What are facts about the weak (Nuclear) force?
- Involved in radioactive beta decay.
- Extremely short range force.
- Is weaker than the strong nuclear force (hence its name).
- Experienced in quark and lepton interactions.
- ASSOCIATED WITH RADIOACTIVE BETA DECAY
What is the exchange particle/force carrier of the weak (nuclear) force?
The W and Z bosons.
What are facts about the electromagnetic force?
- Combination of electrostatic and magnetic forces.
- Has infinite range
- ACTS BETWEEN CHARGES
What is the exchange particle/force carrier of the electromagnetic force?
The photon.
What are facts about the gravitational force?
- Has infinite range
- Weakest of the 4 fundamental forces
- ACTS BETWEEN MASSES - requires large masses to produce significant forces.
What is the exchange particle/force carrier for the gravitational force?
The graviton
What do fermions consist of?
Fermions, the matter particles, consist of quarks (six types: up, down, strange, charm, top, bottom) and leptons (electron, muon and tau, together with their
neutrinos).
In the standard model what does each particle have and what is evidence for this?
In the Standard Model, every particle has an antiparticle and the production of energy in the annihilation of particles is evidence for the existence of antimatter.
Why are protons and the neutrons not fundamental particles?
They are composed of other particles/quarks, (fundamental particles are not). (they are composite
particles).
All baryons are hadrons, but not all hadrons are baryons why is this statement correct?
Baryons are (hadrons as they are) composed of (three) quarks. Mesons/some hadrons are made from a quark - anti-quark pair so are not baryons.
