Particle Physics and The Standard Model

What are the Most Important Questions? A large portion of particle physics asks: “What is the smallest?”

What are the Most Important Questions Atomic Theory

What are the Most Important Questions Once we understood the atom, we realized there were different kinds of atoms ….so we organized them

The Standard Model A theory that explains the properties, behaviors and interactions of the elementary particles and the fundamental forces

The Standard Model 12 Particles 4 Forces 6 Quarks 6 Leptons Model is composed of … 12 Particles 6 Quarks 6 Leptons 4 Forces Bosons (Force Carriers/Gauge Bosons)

Disclaimer *This material touches on the origins of the universe *This material is presented to ensure your awareness of the current scientific theory, not to influence any belief systems.

How did we know there was anything smaller? Cosmic Rays (from outer space) Earth receives high- energy beams of radiation from outer space. Beams strike and interact with particles in our atmosphere

Cosmic Rays Caused particles to break apart into smaller pieces We began to study these, but could not accurately predict where these rays would hit

On Earth, without producing Cosmic Rays, we break atoms apart with ‘atom smashers’ aka particle accelerators Most Famous: Large Hadron Collider (LHC) 17 miles in diameter Spans across the France- Swiss Border

When Atoms Smash… Particles are accelerated close to the speed of light and then… Particles break apart into…Energy …which then forms into any number of different particles

The Standard Model - Hadrons *We used to think protons, neutrons, and electrons were as small as we could go… WRONG! Protons and Neutrons are particles in a category called Hadrons Hadrons  made up of … Quarks

The Standard Model - Quarks Quarks – Fundamental particles that make up other particles. Never seen alone, always in combinations Quarks: Up Charm Top Down Strange Bottom

The Standard Model - Leptons Leptons – Fundamental particles not involved with the nucleus, nor do they combine with other leptons Leptons: Electron Muon Tau Electron Neutrino Muon Neutrino Tau Neutrino

When do I see these? Likelihood of seeing a particle is based on stability and weight. Generation one - lightest and most stable. Generation two - next in stability Generation three - largest and least stable

The Standard Model - Forces All of the universe can be explained by four fundamental forces 4 Gravitational Force 2 Electromagnetic Force 1 Strong Force 3 Weak Force …Strongest force? At the beginning of the universe, it has been hypothesized that these four forces were united in a grand unified theory

The Standard Model - Bosons Bosons – Have different properties than quarks and leptons. But also differ in function. Force Carrier Bosons: Photon - Force carrier for electromagnetic forces Z and W Bosons - Force carriers for the weak force Gluon- Force carrier for the strong force

Main Categories Bosons Hadrons Mesons Fermions Baryons Composite Particles (Made from combinations of fermions) Involved with the Fundamental Forces Mesons Fermions Baryons Fundamental Particles (Nothing smaller that we know of) Protons and Neutrons Quarks Leptons

The Standard Model – Higgs Boson Higgs Boson – Same properties as the other bosons (physically) BUT has a different function This particle gives mass to other particles. Without mass, particles cannot interact.

The Standard Model – The Higgs Field Higgs particles are part of the Higgs Field – which all other particles interact with. As particles move through the Higgs Field, some have a high level of interactions, more mass Some have less interactions, less mass

Why Do We Need Mass? Newton’s Law of Universal Gravitation A force of attraction exists between any objects with mass