1 / 12

Fundamental Forces/Interactions

Fundamental Forces/Interactions. Virtual Particles, Messenger Particles, and Vacuum Fluctuations Energy-time uncertainty relation: Assume a force has a range of 1.5 x 10 -15 m. Estimate the mass of the messenger particle for this force. ConcepTest #94

ainsley-velez
Télécharger la présentation

Fundamental Forces/Interactions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Fundamental Forces/Interactions

  2. Virtual Particles, Messenger Particles, and Vacuum Fluctuations Energy-time uncertainty relation: Assume a force has a range of 1.5 x 10-15 m. Estimate the mass of the messenger particle for this force.

  3. ConcepTest #94 Compare a virtual g photon (the messenger particle for the electromagnetic interaction) and a virtual W particle (a messenger for the weak nuclear interaction). Which lives longer and which has the shorter range? Hold up one card from each column.

  4. Feynman (Interaction) Diagrams, part I Some Rules: time g Virtual particles begin and end on diagram All interactions at a “vertex” Each vertex only gets three lines; must have at least one incoming and at least one outgoing. • At each vertex, • (Electric) Charge must be conserved • Color (Charge) must be conserved • Baryon Number must be conserved • Lepton Number must be conserved (by family) time Feynman Diagram Animations http://www.departments.bucknell.edu/physics/animations/Feynman_diagrams/

  5. Quarks and Color and Camouflage, oh my! What is the quark content of the D++?

  6. ConcepTest #94 Consider the following color combinations in various hadrons or anti-hadrons: Which color combination above correspond to the following? Hold up as many cards as necessary: a) Meson b) Anti-Meson c) Baryon d) Violates the colorless rule

  7. Consider the quark from part b). What was the color of this second quark before it absorbed the gluon? CAMOUFLAGE ConcepTest #95 Consider the complete set of colors and anti-colors: a) A quark emits a green-antired ( ) gluon. What is the color of this quark after the gluon emission? b) Another quark absorbs this green-antired ( ) gluon. What is the color of this quark after it absorbsthis gluon?

  8. The “Gumby” Rule Consider the following (incomplete) Feynman diagram showing a quark changing color as it emits a gluon. Recall that this incomplete Feynman diagram is called a vertex. Which of the following vertices describe allowed reactions?

  9. W effect on leptons: In the vertex diagram shown below, an electron emits a W– particle. What particle (??) emerges after this interaction? W effect on quarks: In the vertex diagram shown below, a Bd quark emits a W– particle. What particle (??) emerges after this interaction? ?? W– time ?? e– W– time Bd Feynman Diagram Animations http://www.departments.bucknell.edu/physics/animations/Feynman_diagrams/

  10. Decay Reactions and Particle Lifetimes Consider the following four particle decays. Determine the interaction through which each particle decays. Then rank the particles in terms of lifetime.

More Related