Classification of particles Flashcards
What are hadrons?
Hadrons are a group of subatomic particles made up of quarks
Can hadrons feel the strong nuclear force name two classes of hadrons? (quarks?)
Yes:
Baryons (3 quarks)
Mesons(quark and anti-quark pair)
Name two common baryons
Protons and neutrons
Name two common mesons
Pions and Kaons
Have quarks ever been discovered on their own
No not to public knowledge in 2022
Could a combination of quarks and anti-quarks exist for baryons?
No (not yet as of 2022) because all baryons and mesons have whole number charges so for baryons they are either all quarks or all anti-quarks in the case of an anti-baryon
How does an anti-meson differ from a meson?
The quark becomes an anti-quark and the original anti-quark becomes a quark.
What is the baryon number?
The number of baryons in an interaction and depends on whether the particle is a baryon, anti-baryon or neither
Which particles have a baryon number of 1
protons, neutrons, (sigma particles tbc)
which particles have a baryon number of 0
leptons and mesons
Which particles have a baryon number of -1
anti-protons and anti-neutrons
what is the baryon number for each of the quarks and name the three different types.
Up: 1/3
Down: 1/3
Strange:1/3
what is the baryon number for each anti-quark?
-1/3
which particle is the most stable baryon?
What does this mean in terms of decay?
proton
Has the longest half-life (10^32 years roughly) of any baryon and is the particle that other baryons eventually decay into
name the most stable baryon and explain why?
proton is the lightest baryon and radioactive decay occurs when heavier particles decay into lighter particles
What would violate the conservation of baryon number and why?
A decay of the proton as it is the lightest baryon and radioactive decay occurs when heavier particles decay into lighter particles
what is the antiparticle of a neutral pion
Itself
which particle is the lightest mesons
Pions
How were pions originally discovered
In cosmic rays and then cloud chamber
What are the four fundamental interactions
the strong force
the weak force
the electromagnetic force
the gravitational force
What does the strong force do?
The strong force keeps the protons and neutrons bound together in a nucleus
What are the four fundamental interactions caused by
an exchange particle/virtual particle
What is the exchange particle of the strong force? and what does this mean?
Pions (are said to MEDIATE the strong nuclear force)
Strong force is transmitted between a proton and neutron by exchange of a pion
What is peculiar about the pions mediating the strong nuclear force?
The pion created is a temporary violation of energy and mass conservation but since it is a virtual particle, it is not directly observed.
Name another particle that is an exchange particle of the strong force.
Gluons
Difference between pions and gluons as mediators of this force are:
Glouns are responsible for binding quarks together, which is called strong interaction
Pions are responsible for binding nucleons together. This is referred to as the strong nuclear force.
Collectively they are referred to as the strong force.
How are kaons produced?
By the strong interaction between pions and protons
Describe the characteristics of Kaons
They are heavy and unstable so normally decay into pions but kaons have long lifetime.
Why do Kaons have unusually long lifetimes?
They contain a strange quark and longer lifetimes is a characteristic of particles containing strange quarks.
How do Kaons decay and give an example of a neutral kaon decaying?
Decay through weak interaction
neutral kaon decaying into a positive pion and negative pion.
What are leptons?
A group of fundamental (elementary) particles - not made up of any other particles so no quarks
Which fundamental force do leptons not interact with other particles via?
Strong nuclear force
They do interact via the weak, gravitational or electromagnetic interactions
Common examples of leptons
The electron, electron neutrino, muon and muon neutrino
