Chapter 2: Fundamental Particles Flashcards
What are antiparticles?
Fundamental particles with the same mass and energy as their corresponding particles but opposite charge and conservation numbers
What are quarks?
Fundamental particles that make up hadrons (eg baryons and mesons). They exert the strong nuclear force on one another.
What are gluons?
One of the four exchange particles responsible for the nuclear strong force. They act between quarks holding them together and have a very short range.
What are exchange particles?
Particles involved in the interaction of particles via the four fundamental forces of nature on the quantum scale. They are created, emitted, absorbed and destroyed between the interacting particles.
What is the exchange particle for electromagnetic force?
Virtual photons
Acts between charged particles
What is the exchange particle for the strong nuclear force?
Gluons
Acts between quarks
What is the exchange particle for the weak nuclear force?
W+, W- Z 0 bosons
Responsible for radioactive decay (not alpha) and nuclear fusion
What is the weak force?
A force a million times weaker than the strong force and acting over a shorter range. It is responsible for beta decay, electron capture and electron-proton collision.
What are leptons?
Fundamental particles that do not feel the strong force (as they are not made of quarks). Includes electron, muons, neutrinos, tauons.
What are hadrons?
Subatomic particles that are made of quarks so feel the strong force. Include baryons and mesons.
What are baryons?
A class of hadron that are made of three quarks. The only stable baryon is the proton. Includes protons and neutrons.
What are mesons?
A class of hadron that is made of a quark and antiquark pair. Includes pions, kaons.
What is lepton number?
A quantum number that is conserved in all particle interactions. Both electron lepton numbers and muon lepton numbers must be conserved.
What particles have a lepton number of 1?
Electron lepton number: electrons, electron neutrino
Muon lepton number: muons, muon neutrino
What is a muon?
A heavy electron (x200 the mass). It decays into an electron (or positron) and two neutrinos.
What are the quark compositions of protons and neutrons (and their anti particles)?
Proton: uud
Neutron: udd
Antiproton: ūūð
Antineutron: ūðð
What are the quark compositions of the pions?
π+ : uð
π- : dū
π° : uū or dð
What are the quark compositions of the kaons?
K+ : uš
K- : sū
K° : dš
What is baryon number, B?
A quantum number that is conserved in all particle interactions. Baryons have a baryon number of +1, anti-baryons have a baryon number of -1 and non-baryons have a baryon number of 0.
What baryon numbers do quarks and antiquarks have?
Quarks: +1/3
Antiquarks: -1/3
What is strangeness?
A quantum number that is conserved in strong interactions but not in weak interactions. This reflects that strange particles are always produced in pairs. Strange quarks have a strangeness of -1.
What are strange particles?
Particles that are produced through the strong interaction but decay through the weak interaction.
What quantities are always conserved?
Charge
Mass-energy
Momentum
Lepton numbers
Baryon number
What quantity is not always conserved in the weak interaction?
Strangeness. Can change by -1, 0 or +1.
