IB Physics Unit 7 Structure of Matter (Quarks, Leptons, Mesons, Baryons, Protons, Fundamental Forces). SME 7.3

for May 2024 syllabus

Quark

Fundamental particles; make up protons and neutrons

Hadron

any particle made up of quarks

Examples of Hadrons

Protons and Neutrons

Proton

uud

Neutron

udd

u

Up

c

Charm

t

Top

d

Down

s

Strange

b

Bottom

Relative charge for quarks ‘uct’

+2/3e

Relative charge for quarks ‘dsb’

-1/3e

Baryons

constructed of 3 quarks

Example of Baryons

protons and neutrons

Mesons

quark and anti quark pair

Fundamental

Not made up of any other particles

Examples of fundamental particles

Electrons, Quarks

Strangeness of Strange quark

-1

Leptons

Fundamental particles

e-

electrons

μ-

Muon

𝜏-

Tau

Ve

electron neutrino

Vμ

Muon Neutrino

V𝜏

Tau Neurino

Charge of 𝜏-, μ- & e-

0.0005u

Emitted with electrons (during beta decay)

Electron-Neutrino

Emitted with Muons

Muon-Neutrino

Emitted with Tau

Tau-Neutrino

Leptons Interact with:

Weak interaction, electromagnetic and gravitational forces

Leptons Do Not interact with:

Strong force

Up Antiparticle

Anti-Up

Charm Antiparticle

Anti-Charm

Top Antiparticle

Anti-top

Down Antiparticle

Anti-Down

Strange Antiparticle

Anti-Strange

Bottom Antiparticle

Anti-Bottom

Charge of Anti-Quarks

Reverse symbol of charge

Denotation of Anti-Quarks

Add dash directly on top of symbol

Lepton Number

Number of laptons in an interaction

Baryon Number of quarks

+1/3

Baryon Number of anti quarks

-1/3

Lepton Number of Leptons

+1

Lepton Number of Anti-Leptons

-1

Lepton Number of Any Particle that is not a Lepton

0

Rule of Lepton Number

Lepton Number is Conserved in all interactions

Protons Stability as Baryons

The most Stable Baryon

Protons Half Life as Baryon

Longest Half-life of any Baryon

Protons Relationship between Baryon stability and mass

Protons are the most Stable baryons as a result of them also being the lightest Baryon.

Proton Half-Life order of magnitude

10³² Years

Electron Antiparticle e+

Positron

Beta Decay occurs through…

The Weak Interaction

Four fundamental Forces

Gravity, Electromagnetism, Strong and Weak Nuclear Forces

Summary of Beta- decay

A neutron turns into a proton emitting an electron and antineutrino

In depth of Beta Decay

Neutron turns into proton because
a down quark turns into an up quark

Summary of Beta+ Decay

A proton turns into a neutron emitting a positron and an electron neutrino

In depth of Beta Decay

A proton turns into a neutron because
an up quark turns into a down quark

Hadrons

Subatomic particles made of quarks

Hadrons idenitty

Either Baryon or Mesons

Hadrons Antiparticle

Anti-Hadrons

Anti-Hadrons identity

Anti-Baryons or Anti-mesons

Hadrons and Mesons important note

All possess an Integer (Whole Number) charge
e.g +1e,

Baryon important note

Combinations of quarks and anti quarks do not exist.

Baryon Number B

Number of Baryons in an interaction

Baryon number of Baryons

B = +1

Baryon Number of Anti-Baryons

B = - 1

Baryon Number of Non-Baryons`

B = 0

Rule of Baryon Number

It is conserved.

Baryon number of Quarks Up Down Stange

1/3

Baryon number of Anti Up, Anti Down, and Anti - Strange

-1/3

Baryon Number of Mesons

B = 0

Examples of Mesons

Pions, Kaons, D mesons, B mesons

Pions Charge information

Can be positive, negative or neutral

Pion Antiparticle

Negative pion

Pions mass and stability

Lightest mesons, and therefore most stable

discovery of pions

discovered in cosmic rays

Pions

Exchange particles of the strong nuclear force

Positive pion

up + anti down

neutral pion

up + anti up | down + anti down

negative pion

anti up + down

Kaons

heavy unstable mesons which normally decay into pions

Conservation of strangeness

Not conserved, Nonexistent

Bosons

“Wingman” particles which mediate interactions based on the four fundamental forces

Mediator of Gravitational Forces

Graviton

Mediator of Weak Forces

W+ W- & Z { W-Bosons & Z-Bosons

Mediator of Electromagnetic Forces

Photons γ

Mediator of Strong Nuclear Forces

Gluons (Between quarks) and Plons (between nucleons)

Strong Nuclear forces and Leptons

Leptons Cannot interact with the strong nuclear force, since they are not made of quarks

Graphical interpretation of Strong nuclear force

Becomes zero after 3.0fm

Repulsive (of strong forces)

closer than 0.5fm

Attractive (of strong forces)

up to around 3.0 fm

Exchange particles

Temporary particles that mediate/carry/transmit a fundamental force between interacting particles

The Higgs-Boson

A particle responsible for the mass of all other particles