Questions and Answers
What distinguishes elementary particles from composite particles?
Which of the following is NOT a fundamental fermion?
How are matter and anti-matter particles related?
What is the primary function of bosons in the Standard Model?
Signup and view all the answers
Which of the following is NOT one of the quantum numbers used to describe elementary particles?
Signup and view all the answers
What does the equation $1e = \frac{2}{3}e + \frac{2}{3}e - \frac{1}{3}e$ exemplify about particles?
Signup and view all the answers
How many flavours of quarks are present in the Standard Model?
Signup and view all the answers
What is the significance of the Standard Model in particle physics?
Signup and view all the answers
What is the sum of the Baryon Numbers for a combination of three Quarks?
Signup and view all the answers
Which combination of particles satisfies the colour charge requirement for a Baryon?
Signup and view all the answers
Which particles are examples of Leptons?
Signup and view all the answers
What type of combination defines a Meson?
Signup and view all the answers
Which fundamental force is associated with the exchange of gluons?
Signup and view all the answers
What is required for a valid particle interaction concerning charge?
Signup and view all the answers
Which Gauge Boson is responsible for the Weak Nuclear Force?
Signup and view all the answers
Which of the following describes a Pair production phenomenon?
Signup and view all the answers
How many types of Colour Charge are there for Quarks?
Signup and view all the answers
What is a characteristic of Mesons?
Signup and view all the answers
What does the Baryon Number conservation principle indicate?
Signup and view all the answers
What is the reverse process where a photon creates matter?
Signup and view all the answers
Which of the following is an example of charge conservation during a neutron decay?
Signup and view all the answers
Which concept allows physicists to predict the existence of new particles?
Signup and view all the answers
Study Notes
Elementary Particles
- Elementary particles are the smallest known building blocks of the universe, with no internal structure and considered zero-dimensional points.
- Types of elementary particles included are fundamental fermions (matter and antimatter) and bosons (mediators of forces).
- Composite particles contain two or more elementary particles.
Matter and Antimatter
- Each matter particle has a corresponding antimatter particle, denoted with a line above its symbol.
- Matter and antimatter particles share the same mass but have opposite electric charges and quantum numbers.
- When a matter particle collides with its antimatter counterpart, they annihilate, producing other subatomic particles.
Standard Model
- The Standard Model is the mathematical framework that describes elementary particles and their interactions.
- Quantum numbers guide the classification of particles, including charge, spin, baryon number, and color charge.
- Example: A proton has a charge of +1e consisting of two up quarks and one down quark.
Fermions
- There are 12 fermions in the Standard Model, categorized into quarks and leptons.
- Six flavors of quarks: up, down, charm, strange, top, and bottom; their charges are either +2/3e or -1/3e.
- Hadrons, made of quarks, are categorized as baryons (3 quarks) or mesons (2 quarks).
Color Charge
- Color charge is essential for forming stable combinations of quarks, assigned as red, green, and blue (and corresponding anti-colors).
- Baryons require combinations that yield a color-neutral (white) status, with protons and neutrons as common examples.
- Quarks carry a baryon number of +1/3, while anti-quarks have -1/3, ensuring overall baryon number conservation.
Leptons
- Unlike quarks, leptons exist independently and interact via weak nuclear force.
- Common leptons include the electron, muon, and tau, each with a corresponding neutrino.
- Example of interaction: Beta-minus decay involves the emission of an electron and anti-neutrino.
Fundamental Forces and Gauge Bosons
- Four fundamental forces govern interactions: strong, electromagnetic, weak, and gravitational.
- Gauge bosons are mediators for these forces:
- Gluon: mediates the strong nuclear force.
- Photon: carries the electromagnetic force.
- Z and W bosons: mediate weak nuclear force.
- The graviton is a theoretical particle proposed for gravitational interactions.
Conservation Laws
- Conservation of mass-energy and momentum is vital; annihilation produces energy based on E=mc².
- Charge conservation dictates that the total charge before and after interactions must remain equal.
- Baryon and lepton number conservation is essential during particle interactions to avoid discrepancies.
Neutron Decay Example
- Neutron decays to a proton demonstrating conservation laws:
- Mass-energy: 939.57 → 938.27 + 0.511 + 0 + 0.779
- Charge: 0e → 1e + -1e + 0 + 0
- Baryon number: 1 → 1 + 0 + 0 + 0
- Lepton number: 0 → 0 + 1 + -1 + 0
Symmetries in Physics
- Charge reversal: interactions hold when all particles are replaced with their antiparticles.
- Parity symmetry: laws of physics remain unchanged if particle movements are inverted.
- Time reversal: interactions can occur in reverse without violating physical laws.
CPT Symmetry
- CPT (Charge, Parity, Time) symmetry implies a mirror-image universe follows the same physical laws as our own.
Supersymmetry
- Supersymmetry extends the Standard Model, predicting partner particles for every Standard Model particle.
- Addresses limitations in the Standard Model, particularly regarding the Higgs boson mass.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
