Chapter 2 Flashcards
Muon
A heavy electron (symbol μ) a negatively charged particle with a rest mass over 200 times the rest mass of the electron.
Pion
Or a meson π a particle which can be positively charged or negatively charged or neutral and has a rest mass greater than a muon but less than proton.
Kaon
Or K meson which also can be positively charged (K+) negatively charged (K-) or neutral (K0) and has a rest mass greater than a pion still less than a proton.
Decaying particles
kaon
Kaon can decay into pions or a muon and an anti muon
Or an neutrino or an antineutrino
Decaying particles
Charged pion
Decay into a muon and an anti muon
Or an neutrino and an antineutrino
A meson can decay into high energy photons.
Decaying particles
Muon
Decays into electrons and an antineutrino
An antimuon decays into a positron and a neutrino
Decays always obey the conservation rules for energy momentum and charged
What are the two groups
Hadrons - particles and antiparticles that can interact through the strong interaction
Leptons - electrons, positrons, muons and anti muons, neutrinos and their antiparticles are classified as leptons because they cannot interact through the strong interaction. They interact through the weak interaction and in this case of electrons, positrons, muons and anti muons through the electromagnetic interaction.
Two defining characteristics of hadrons
They can interact via the strong nuclear force
They are not fundamental particles, they have a structure
Two defining characteristics of leptons
They do not interact with a strong interaction they interact through weak interactions
Experience strong nuclear force
respond only to the electromagnetic force, weak force, and gravitational force and are not affected by the strong force.
The rest energy of the products
Total energy before - the kinetic energy of products
Baryons
Have 3 quarks which decay into protons which are directly or indirectly.
Mesons
Have 2 quarks, quarks and anitquarks which do not decay into a proton
Mesons are hadrons that do not include protons in their decay products kaons and pions but not baryons
Baryons and Anti Baryons
Anti proton
Anti neutron
Neutron
Proton
Mesons
Kaon
Pion
Quark
Protons and neutrons and other hadrons which consists of quarks. There are three types of quarks, the up quark the down quark the strange quark.
Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. All commonly observable matter is composed of up quarks, down quarks and electrons.
Anti quark
The anti particle of a quark
Neutrino
Neutrino travel as fast as light, they are produced in much smaller numbers when particles in accelerators collide.
Neutrinos and antineutrinos are produced in beta decays were different from those produced by muon decays. In effect neutrinos and Anti neutrinos from muon and antimuon decays create only muons and no electrons when they interact with protons and neutrons.
Lepton rule
Leptons can change into leptons through the weak interaction and can be produced or annihilation in particle - antiparticle interactions.
Eg
N = p + e-
Charge = 1 = +1 -1 = balanced
Lepton = 0 = 0 +1 -1
Full eq
N = p + e- + -Ve
Strangeness number
A strangeness number is assigned to every particle and antiparticle on the basis that strangeness is always conserved in the strong interaction but not in a weak interaction pr a decay involving a strange quark or antiquark
Strangeness
Strangeness is always conserved in a strong interaction whereas strangeness can change by 0,+1,-1 in weak interactions.
Quark combination
Mesons
Mesons are hadrons each can be consisting of a quark and an antiquark.
A meson can be an quark corresponding antiquark combination
Each pair of changed mesons is a particle-anti particle pair
There are two uncharged koans the K0 meson and the -k0 meson
The antiparticle of any meson is a quark-antiquark pair and therefore another meson
Quark combination
Baryons and anti baryons
Are hadrons that consists of three quarks fro baryons or three antiquarks for an anti baryon
A proton is the uud combination
A neutron is the udd combination
An antiproton is the -u-u-d combination
The Σ particle is a baryon containing a strange quark
The proton is the only stable baryon. A free neutron decays into a proton releasing an electron and an electron antineutrino as beta - decay
Conservation rule
Conservation of engery, momentum, charge, bayron number and lepton number applies to all particle interactions. Conservation of strangeness applies to strong interactions only.
Particles
Particles and antiparticles posses energy they may be charged or uncharged they may have non zero strangeness and they may not be stable. They obtain conservation rule when they interact.
Conservation of enrgy and conservation of charge
this applies t all chnages in science not just to all particle and antiparticle interactions and decays. Rember conservation of energy includes the rest energy of the particles.
Conservation rule used only for paeticles and anitparticle interaction and decays
These are essentially particle counting rules based on, what reactions are observed and what reactions are not observed.
Conservation law for leptons
In any change the total lepton number for each lepton branch before the change is equal to the total lepton number for that branch after the change.
When is strangeness conserved
In any strong interaction
Plain what happens during beta plus decay in terms of quarks
An up quark in a proton(uud) of the nucleus changes into a down quark so the proton E comes a neutron (udd).
Hadrons
made up of quarks
made up of smaller particles
baryons = 3 quarks
decays into protons
Mesons = 2 quarks
one quark , one qntiquark
Do not decay into protons
K Mesons decays down
π mesons = never gave a strange or antistrange quark
Experience a strong interaction
Conserved
Baryon
Charge
Lepton
Not conserved
Strangeness
Strong interaction
Gluon
Weak interaction
Boson
Beta minus
The proton emitting an electron and an anti electron and neutrino
⁰_₁ B + -Ve
Beta plus
Proton turns into a neutron emitting a positron and an electron neutrino
A = tope number
A
B + ve
\+1
