Exchange Particles And Feynman Diagrams

Question 0

Particle exchange explain repulsion and ……

Answer 0

Attraction

Question 1

What are forces caused by

Answer 1

Particle exchange

Question 2

What are the exchange particles called

Answer 2

GAUGE BOSONS

Virtual particles- only exist very short time

Question 3

What is the repulsion between two protons caused by

Answer 3

Exchange of VIRTUAL PHOTONS- the gauge bosons of the electromagnetic force

Question 4

Name the 4 fundamental forces, each gauge boson and the particles affected

Answer 4

Type of interaction/Gauge boson/Particles affected
Strong/gluon/hadrons only
Electromagnetic/photon(y)/charge particles only
Weak/W+W-Z0/all types
Gravity/graviton?/all types

Question 5

Why do particle physicist never bother about gravity

Answer 5

Incredibly FEEBLY comPared to other types of interaction
Only really matters BIG MASSES- stars planets

Graviton may exist- no evidence

Question 6

The larger the mass of a gauge boson the …. The range of force

Answer 6

Shorter

Question 7

Why does the W boson have a very SHORT RANGE

Answer 7

Mass of 100 times that of a proton

Creating a virtual W particle used so much ENERGY
that it can only EXIST short time
And can’t TRAVEL far

Question 8

Name which gauge boson has an infinite range and why

Answer 8

PHOTON as it has ZERO MASS

Question 9

How are GAUGE BOSONS represented in Feynman diagrams

Answer 9

Wiggly lines

Question 10

How are other particles represented in Feynman diagrams

Answer 10

Straight lines

Question 11

What are the three rules for drawing Feynman diagrams

Answer 11

1) INCOMING particles start at the BOTTOM of the diagram and move upwards
2) The BARYONS stay on one side and the LEPTONS stay on the other
3) CHARGES on both sides must be balanced

Question 12

What happens in electromagnetic repulsion

Answer 12

When 2 particles with EQUAL CHARGES get close to each other, they REPEL

(Exchange of a virtual photon) going to the LEFT

Question 13

Explain electron capture

Answer 13

Of course E & P attracted by ELECTROMAGNETIC INTERACTION between them
But if P CAPTURED an E
The WEAK INTERACTION can make this happen

Question 14

Explain the Feynman diagram for electron capture

Answer 14

Bottom left PROTON
Bottom right ELECTRON

Gauge boson of W+ going RIGHT

Top left NEUTRON
Top right ELECTRON-NEUTRINO

Question 15

What is a electron-proton collision

Answer 15

Electron COLLIDES with a proton

Equation same as electron capture but (W-) boson (left)

Question 16

A W- particle going to the left has the same effect as a W+ particle going to the ….

Answer 16

Right

Question 17

What does the W bosons carry from one side of a Feynman diagram to the other

Answer 17

Charge

In order to make each side balanced

Question 18

Describe the Feynman diagram for a beta-plus(minus) decay

Answer 18

Bottom NEUTRON (proton)

W- gauge boson traveling right

Top left PROTON (neutron)
Top right ELECTRON (positron)
Top right second ANTINEUTRINO (neutrino)

Question 19

Talk about electron capture in more detail

Answer 19

Orbiting electron
Interacts with proton from nucleus
U quark changes to a D quark
(Neutron gives off from proton)

Question 20

State one difference between a W exchange particle and a photon

Answer 20

Photon has 0 mass

Question 21

Similarities between Hadrons and leptons

Answer 21

Both have rest mass
Both affected by weak interaction
Both experience electromagnetic interaction