Standard Model Physicists have developed a theory called “The Standard Model” that explains what the world is and what holds it together.
Standard Model • It was once thought that the fundamental particles were electrons, protons, neutrons. • Now we find smaller subatomic particles – quarks & leptons that comprise matter. • Forces are carried by particles too!
All matter either Hadrons or Leptons. p+ & no Quarks can’t exist alone.
Protons, Neutrons:baryons made of only up & down quarks. • How many up & down quarks in a p+? • Charge = +1 • Baryons have 3 quarks only. • 2 up & 1 down. • u + u + d • +2/3 +2/3 – 1/3 = +1
How many up & down quarks in a no? • Charge = 0 • 1 up & 2 down. • u d d • +2/3 -1/3 -1/3 = 0
Leptons • The most familiar member of this group is the electron e, but there are also heavier particles called the muon m and the tau t. • For each of those, there is a smaller “partner” called a neutrino n . • The leptons are all capable of independent existence.
All particles have anti-particles same mass. Antiparticles behave just like their corresponding matter particles, except they have opposite charges. A proton is electrically positive - an antiproton is negative. Gravity affects matter and antimatter the same way. When a matter & corresponding antimatter meet, they annihilate into pure energy!
A particle is composed of 2 charm, & 1 bottom quark. • Write the symbols & charges for all the particles. • Is it a meson, lepton or baryon? • c c b • +2/3 +2/3 -1/3 What is it’s charge? • +1. • Baryon.
A particle is composed of 1 anti-strange, & 1 down quark. • Write the symbols & charges for all the particles. • Is it a meson, lepton or baryon? • s d • +1/3 -1/3 What is it’s charge? • 0. • Meson.
Forces & Force Exchange Particles4 Fundamental Forces The universe exists because the fundamental particles interact. These interactions include 4 attractive & repulsive forces, decay, & annihilation. • Strong Nuclear (Nuclear) • Electromagnetic • Weak (Nuclear) • Gravity
Strong Force • Short Range, Attractive only – holds nuclear particles together. • Particle = gluons.
Electromagnetic Force • Long range. Attracts & repels charged particles (Coulomb’s Law). • Carrier particle = photon.
Weak Force • In the nucleus. Involved with decay of particles. Short range. The carrier particles of the weak interactions are the W+, W-, and the Z bosons.
Gravity • Long range weakest force. Attractive only. • The gravity force carrier particle has not been found. It, however, is predicted to exist and may someday be found: the graviton.
Quarks & Leptons 5:40 min.http://www.youtube.com/watch?v=aTFCKbZw8QY Hwk: Read Text 25-4 pg 917-923 Do pg 923 #1,2 Pg 928 #30 - 37
List 2 pieces of evidence that light is a wave. • Diffraction • Interference. List 1 piece of evidence that light is a stream of particles. • Photoelectric effect List 1 piece of evidence for the Bohr model of the atom. • Emission or Absorption spectra
The charge on an anti-up quark would be: • +1 • -1 • +2/3 • -2/3 Note: Antiparticles have a bar over the symbol.
This particle is a: • Lepton • Proton • Meson • neutron
Cern Standard Modelhttp://www.youtube.com/watch?v=V0KjXsGRvoA&feature=related5 minutes
Comprehensive Standard Model Summery(15 minutes)Cassiopeiahttp://www.youtube.com/watch?v=K6i-qE8AigE
Quantum Song • http://www.youtube.com/watch?feature=player_detailpage&v=DZGINaRUEkU
What is Higgs Boson 3:30 • http://www.youtube.com/watch?v=RIg1Vh7uPyw • What now for the Higgs 8:00 min w/ad. • http://www.youtube.com/watch?v=649iUqrOKuE