Unit 1 section 1 particle interactions

exchange particle: a virtual particle which allows forces to act in a particle interaction.

repulsion:

- skaters facing each other

- they throw a ball to each other

- each timer the ball is thrown and caught it transfers momentum, which is mass multiplied by velocity.

attraction:

- skaters facing away from each other.

- each time a boomerang is thrown and caught it pushes the people together.

the people represent particles and the thrown object represents the exchange particle that causes the force.

the strong interaction has the gluon, g as its exchange particle and the particles it affects are hadrons

the electromagnetic interaction has the virtual photon, y as its exchange particle and the particles it affects are only charged particles.

the weak interaction has the W+/W- boson as its exchange particle and it affects all types of particles

gravity possibly has the graviton as its exchange particle and it affect all types of particles.

- exchange particles are represented by wiggly lines.

- other particles are represented by straight lines.

- incoming particles start at the bottom of the diagram and move upwards.

- baryons and leptons stay on seperate sides of the diagram.

- the W boson carries charge from one side of the diagram to the other - makes sure charges balance.

- a W- particle going left has the same affect as a W+ particle going to the right.