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Graviton and other particle interections 
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#1
Aug1414, 09:24 AM

P: 78

We know that graviton spin is 2 so other lepton and quarks spin is 1/2 I am confused because If Graviton and a quark or maybe a lepton make an interaction than the last spin must be 3/2 or 5/2 but theres no particle exist in this spin quantity.It means theres no particle called graviton or I dont know I am confused
Thanks 


#2
Aug1414, 09:27 AM

P: 928

You only add spins if you have a particle which is the bound state of other particles. But not all kinds of interactions give bound states!



#3
Aug1414, 09:36 AM

P: 78

Whats bound state I googled but its hard to understand



#4
Aug1414, 09:37 AM

P: 928

Graviton and other particle interections



#5
Aug1414, 09:51 AM

P: 78

I lookes there But I didnt undertsand I am 16 years old and I dont know QM. Its complicated and I dont know english very well.



#6
Aug1414, 09:54 AM

P: 78

Can you tell me more specific so you are trying to tell me theres a graviton but is not interact with other particles.
Or its interacts ? 


#7
Aug1414, 09:59 AM

P: 928

OK. The point is, in some situations, the interaction is somehow that the particles are going to remain close to each other. In these situations, we say that they formed a bound state, a composite particle. Like a proton which is formed from two up quarks and one down quark.
But for some other situations, the particles just attract or repel each other for some time and then leave each other alone. These are called scattering processes or sometimes collisions. 


#8
Aug1414, 10:17 AM

P: 78

I ask it because I read a book about particle phyiscs and the author said that spin is conserved its true or not ?
And thanks for explanation Thanks I understand it 


#9
Aug1414, 12:41 PM

Mentor
P: 12,053

Total angular momentum is conserved. Spin is one part, but the motion of particles can contribute to the angular momentum as well.
Yes a (hypothetical) graviton would interact with other particles. 


#10
Aug1414, 07:53 PM

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PF Gold
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#11
Aug1414, 08:03 PM

P: 1,027

As for the photonalpha particle interactions, in case the alpha particle absorbs a photon, it's going to get excited and so will get orbital momentum to conserve the angular momentum. Is giving composite particles for this case good?



#12
Aug1514, 01:58 AM

P: 78

Am I wrong. 


#13
Aug1514, 05:37 AM

Emeritus
Sci Advisor
PF Gold
P: 16,462




#14
Aug1514, 05:59 AM

P: 1,027

if it doesn't absorb the photon then the alpha+gamma will give alpha+gamma



#15
Aug1514, 07:33 AM

Emeritus
Sci Advisor
PF Gold
P: 16,462

Chris, you are not helping. What I am trying to get across is the idea that you can have an interaction with no exchange of angular momentum. Quibbling does not help.



#16
Aug1614, 09:30 AM

Mentor
P: 12,053

Collision with i. 


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