Conservation principles and particle-particle reactions

  • #1
New poster has been reminded to use the Homework Help Template in the schoolwork forums
Please can someone help explain these to me? I have completed a-d but I'm not how e works. I thought gamma was an exchange particle so should it then decay further???

 

Attachments

  • Screen Shot 2018-07-24 at 12.12.01 am.png
    Screen Shot 2018-07-24 at 12.12.01 am.png
    8.2 KB · Views: 250
Last edited by a moderator:

Answers and Replies

  • #2
hilbert2
Science Advisor
Insights Author
Gold Member
1,488
514
The ##\gamma## is a photon that forms in electron-positron annihilation in part (e). You're supposed to check that charge conservation, lepton number conservation, energy-momentum conservation and others are satisfied in these reactions. For example, the charge conservation in the reaction (e) is okay because both the reactants and products have total electric charge of zero.
 
  • Like
Likes Jimmy Ridley
  • #3
The ##\gamma## is a photon that forms in electron-positron annihilation in part (e). You're supposed to check that charge conservation, lepton number conservation, energy-momentum conservation and others are satisfied in these reactions. For example, the charge conservation in the reaction (e) is okay because both the reactants and products have total electric charge of zero.

okay so for (e)

charge is conserved
baryon number is conserved
and lepton number is conserved?
 
  • #4
hilbert2
Science Advisor
Insights Author
Gold Member
1,488
514
Yes, charge is conserved, and there are no baryons in the reaction so the baryon number is zero on both sides. The electron and positron have electron lepton numbers of 1 and -1, so they also sum to 0. Now you should also show somehow that the four-momentum can be conserved in that relativistic collision where an electron and positron turn into two photons.
 
  • Like
Likes Jimmy Ridley
  • #5
Yes, charge is conserved, and there are no baryons in the reaction so the baryon number is zero on both sides. The electron and positron have electron lepton numbers of -1 and 1, so they also sum to 0. Now you should also show somehow that the four-momentum can be conserved in that relativistic collision where an electron and positron turn into two photons.
okay thank you so much, am I also right is saying that (f) is not possible, as

charge is conserved
but baryon number is not conserved as it has baryon number 0 on the left, and 1 on the right? (the neutron has baryon number 1 and the photon has baryon number 0)?
 
  • #6
hilbert2
Science Advisor
Insights Author
Gold Member
1,488
514
charge is conserved
but baryon number is not conserved as it has baryon number 0 on the left, and 1 on the right? (the neutron has baryon number 1 and the photon has baryon number 0)?

It would seem like that to me, but let's wait if someone more professional in particles physics agrees with this.
 
  • Like
Likes Jimmy Ridley

Related Threads on Conservation principles and particle-particle reactions

  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
3
Views
3K
Replies
2
Views
1K
Replies
1
Views
1K
Replies
1
Views
15K
Replies
6
Views
2K
  • Last Post
Replies
2
Views
2K
Replies
32
Views
1K
Top