• Support PF! Buy your school textbooks, materials and every day products Here!

Particle decay and relativity

  • Thread starter faen
  • Start date
140
0
1. Homework Statement

A particle with mass M decays into 2 particles of equal mass m.

1: Calculate the speed of the decay particles

2: Concider the case ρ->[tex]\Pi\Pi[/tex]: M = 770 MeV and m[tex]\Pi[/tex]= 140 MeV

2. Homework Equations

m = [tex]\gamma[/tex]m(restmass) ?

3. The Attempt at a Solution

I suppose M/2 is restmass and found an expression for the speed. However since the mass increase when the speed approaches the speed of light, this would imply that m is a larger number than M/2. But in task 2, it says M/2 is larger than m[tex]\Pi[/tex], which implies i've done something wrong.

Please help me solve this task or find out what i did wrong.
 

Answers and Replies

nrqed
Science Advisor
Homework Helper
Gold Member
3,540
181
1. Homework Statement

A particle with mass M decays into 2 particles of equal mass m.

1: Calculate the speed of the decay particles

2: Concider the case ρ->[tex]\Pi\Pi[/tex]: M = 770 MeV and m[tex]\Pi[/tex]= 140 MeV

2. Homework Equations

m = [tex]\gamma[/tex]m(restmass) ?

3. The Attempt at a Solution

I suppose M/2 is restmass and found an expression for the speed. However since the mass increase when the speed approaches the speed of light, this would imply that m is a larger number than M/2. But in task 2, it says M/2 is larger than m[tex]\Pi[/tex], which implies i've done something wrong.

Please help me solve this task or find out what i did wrong.

The question is ambiguous since you don't say in what frame the calculation is done. I assume in the rest frame of the decaying particle? Then the eenrgy of each produced particle is M/2 and this is equal to [tex] \gamma m c^2 [/tex] where m is the mass of each produced particle.
 
140
0
The question is ambiguous since you don't say in what frame the calculation is done. I assume in the rest frame of the decaying particle? Then the eenrgy of each produced particle is M/2 and this is equal to [tex] \gamma m c^2 [/tex] where m is the mass of each produced particle.
Ok now i understand it, thank you for the answer. :)
 
Last edited:

Related Threads for: Particle decay and relativity

  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
12
Views
10K
Replies
8
Views
6K
  • Last Post
Replies
2
Views
2K
Replies
6
Views
972
Replies
1
Views
4K
  • Last Post
2
Replies
36
Views
3K
  • Last Post
Replies
3
Views
2K
Top