Particles/antiparticles Flashcards
what is antimatter
its made of antiparticles. all particles have antiparticles. they have the same mass and energy but opposite charge
antiparticles of protons, neutrons, electrons and neutrinos
anti-proton
anti-neutron
positron
anti-neutrino
how are antiparticles notated
with a line above the regular notation
what are the four fundamental forces
weak force
strong force
electromagnetism
gravity
what is the weak force
it affects all particles. it’s responsible for beta plus/minus decay. it’s very weak and short-ranged
what is the strong force
the strongest of the four forces but is very short-ranged. only experienced by hadrons. its attractive is the distance is over 0.5fm and repulsive is less
what is gravity
the weakest of the four forces, experience by all matter. Purley attractive force
what is the electromagnetic force
it’s very strong and very long-ranged. it’s responsible for the interaction between charged objects. most forces we experience are because of it
what is an exchange particle
the particles responsible for the interaction between two forces
the fundamental forces exchange particles
strong- gluon, pions
weak- W+ , W- , Z^0 bosons
electromagnetism- virtual photon (Y)
gravity- unknown
why is it called a virtual photon
it only exists fora very short time.
what direction to exchange particles travel for objects to feel a force
away from each other
whats a Feynman diagram
diagrams that represent particle interactions
rules for drawing a Feynman diagram (7)
- particles move upwards
- particles have straight lines
- exchange particles have wiggle lines
- hadrons on left, leptons on right
- particles cant cross paths
- charge entering equals the charge exiting
- a W+ from left to right is same as W- from right to left
what is beta minus decay (Feynman diagram)
a neutron decays into a proton and a W- boson which decays into an electron and antineutrino
what is beta plus decay (Feynman diagram)
a proton decays into a neutron and a W+ boson which decays into a positron and neutrino
difference between electron capture and an electron-proton collision on a Feynman diagram
the boson. W+ for capture and W- for collision
what is a hadron
particles that feel the strong nuclear force, they are made of quarks
what are baryons
a type of hadron made of 3 quarks. protons are the only stable baryon. all others will eventually decay into protons
what is a quantum number
a number that can only be an integer
waht is the baryon number
a number (B) that notates the number of baryons present. its a quantum number. it must be conserved
what are mesons
a type of hadron made of a quark and antiquark. they have a baryon number B=0 (they aren’t baryons)
what are pions and kaons
types of mesons. pions are the exchange particles of the strong force. kaons are massive pions and will decay into pions. notations- π+ , π- , π^0(pions) or K+ , K- , K^0 (kaons)
what are leptons
fundamental particles (not made of smaller particles). they don’t feel the strong nuclear force. (e.g. electrons, neutrinos)
what are muons
a type of lepton. negative charge, heavier than electrons, unstable and decay into electrons
what are neutrinos
a type of lepton. electrons and muons have there own types of neutrino (Ve and Vμ). they are almost massless and have zero charges.
whats the lepton number
a number(Le or Lμ) notating the number of leptons. it’s different for each type of lepton. its a quantum number. each must be conserved individually.
what is strangeness
a property of matter. its a quantum number. strange quarks have strangeness -1 and the anti versions have +1. its only conserved in the strong interaction
how are strange particles made and decay
they are made by the strong interaction but decay via the weak one which is why they are produced in pairs
the fundamental properties of matter
charge
mass
strangeness
baryon number
the three types of quarks
up
down
strange
properties of the three quarks
name: symbol: charge: baryon number: strangeness:
up u 2/3 1/3 0
down d -1/3 1/3 0
strange s -1/3 1/3 -1
properties of antiquarks
opposite to regular versions. and the symbols have a line over the top
what is a proton made of
two up and one down quarks. charge adds to +1 and baryon number adds to +1
what is a neutron made of
two down and one up quarks. charge adds to 0 and baryon number adds to +1
what are antiprotons and antineutrons made of
the same quarks but their anti versions. the charge of the anti-proton adds to -1 and antineutron to 0. the baryon number of both adds to -1
what are pions and kaons made of
pions have up and down (and anti version) quarks only
kaons have one strange/ anti-strange quark
can quarks change type
yes- via the weak interaction
how do we know that beta decay governed by the weak force
a proton decays into a neutron or a neutron decays into a proton meaning a quark has to change type which can only be down by the weak force
