Feynman diagram

  • #1
15
0

Homework Statement


Screen Shot 2018-05-26 at 6.59.37 pm.png


Homework Equations




The Attempt at a Solution


I worked out that the baryon number of X is 0 and the lepton number is +1 which means x is a lepton.
However, when I work out the charge of X, do I add W+ to the left hand side or right hand side of the equation? [/B]
 

Attachments

Answers and Replies

  • #2
Simon Bridge
Science Advisor
Homework Helper
17,857
1,655
Which way does the W+ go?
Hint: law of conservation of charge.
 
  • #3
15
0
Which way does the W+ go?
Hint: law of conservation of charge.
from the proton to the neutron? because proton is +1?
 
  • #4
Orodruin
Staff Emeritus
Science Advisor
Homework Helper
Insights Author
Gold Member
16,829
6,652
Which way does the W+ go?
Hint: law of conservation of charge.
from the proton to the neutron? because proton is +1?
It should be pointed out that internal lines in Feynman diagrams do not ”go” in any direction. As such, the labelling of ##W^+## in the diagram is dubious as the diagram equally well represents the other time ordering where one might say that it is a ##W^-## going from the right to the left. In fact, people often take Feynman diagrams way too literally as if the lines were representing the worldlines of little balls moving around. They are nothing but (very very useful) graphical representations of terms in a mathematical series expansion.

When it comes to charge conservation, you can always draw an arrow on a line representing the charge flow and use charge conservation at each vertex. (You can do this for any charge, not just electric charge.)

You are correct that it must be a lepton. What charge must it have based on the above?
 
  • Like
Likes Simon Bridge
  • #5
15
0
It should be pointed out that internal lines in Feynman diagrams do not ”go” in any direction. As such, the labelling of ##W^+## in the diagram is dubious as the diagram equally well represents the other time ordering where one might say that it is a ##W^-## going from the right to the left. In fact, people often take Feynman diagrams way too literally as if the lines were representing the worldlines of little balls moving around. They are nothing but (very very useful) graphical representations of terms in a mathematical series expansion.

When it comes to charge conservation, you can always draw an arrow on a line representing the charge flow and use charge conservation at each vertex. (You can do this for any charge, not just electric charge.)

You are correct that it must be a lepton. What charge must it have based on the above?
zero? so it is a neutrino?
 
  • #8
nrqed
Science Advisor
Homework Helper
Gold Member
3,737
279

Related Threads on Feynman diagram

  • Last Post
Replies
0
Views
2K
  • Last Post
Replies
7
Views
2K
  • Last Post
Replies
7
Views
3K
  • Last Post
Replies
3
Views
806
  • Last Post
Replies
2
Views
5K
  • Last Post
Replies
0
Views
1K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
3
Views
371
  • Last Post
Replies
14
Views
5K
  • Last Post
Replies
3
Views
1K
Top