Neutral Pion Decay: Exploring Spin Conservation

In summary, the conversation discusses the decay of a neutral pion into two photons and the potential issue of spin conservation. The question of whether anti-particles and anti-quarks have negative spin is also raised. It is suggested that perhaps the pion does not have spin 1, which would make the question about spin conservation a moot point. Additionally, it is noted that even if the pion did have spin 1, it is still possible for it to decay into two photons. However, it is then mentioned that according to a study by Yang in 1950, a spin-1 particle cannot decay into two photons, adding further confusion to the discussion.
  • #1
simon96c
11
0
Hi everyone,
I am curious about how a neutral pion decays in two photons. I don't understand how it is possible since the pion has spin = 1 and the photons have spin = 1 as well: doesn't this mean that spin is not conserved in this decay? What am I missing?

Another question I have is about spin: do anti-particles and anti-quarks have negative spin, or is the spin always positive?

Sorry for the silly questions and thanks to everyone in advance :)
 
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  • #2
simon96c said:
Hi everyone,
I am curious about how a neutral pion decays in two photons. I don't understand how it is possible since the pion has spin = 1 and the photons have spin = 1 as well: doesn't this mean that spin is not conserved in this decay? What am I missing?

Another question I have is about spin: do anti-particles and anti-quarks have negative spin, or is the spin always positive?

Sorry for the silly questions and thanks to everyone in advance :)

Perhaps the pion doesn't have spin 1? If the pion has spin 0, say, that might indeed make it a silly question.
 
  • #3
simon96c said:
What am I missing?

How sure are you that the pion has spin 1?
 
  • #4
PeroK said:
Perhaps the pion doesn't have spin 1? If the pion has spin 0, say, that might indeed make it a silly question.
Apart from this, it is perfectly possible for two spin-1 particles to couple to a spin-1 so even if the pion had spin 1 it would not be that strange.
 
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Likes PeroK
  • #5
Actually, a spin-1 particle cannot decay to two photons. See Yang, Physical Review 77: 242–245 (1950).
 
  • #6
Vanadium 50 said:
Actually, a spin-1 particle cannot decay to two photons. See Yang, Physical Review 77: 242–245 (1950).
Not disputing that. All I am saying is that it is not as easy as saying ##1+1 \neq 1##.
 

Question 1: What is a neutral pion and how does it decay?

Neutral pion is a subatomic particle made up of two quarks (one up quark and one anti-down quark) and its corresponding antiquarks. It decays into two photons through the strong nuclear force.

Question 2: What is spin conservation and why is it important in neutral pion decay?

Spin conservation is the principle that the total spin of a system remains constant before and after a decay or interaction. In neutral pion decay, spin conservation is important because it helps determine the angular momentum of the particles involved in the decay.

Question 3: How is spin conservation observed in neutral pion decay experiments?

In experiments, the spin of the neutral pion is determined by measuring the spin of its decay products, the two photons. The spin of the photons should add up to the spin of the initial neutral pion in order to conserve spin.

Question 4: What is the significance of studying neutral pion decay and spin conservation?

Studying neutral pion decay and spin conservation can help us better understand the fundamental laws of the universe, such as the conservation of angular momentum and the behavior of subatomic particles. It also has practical applications in fields such as nuclear physics and medical imaging.

Question 5: Are there any current or future research projects focused on neutral pion decay and spin conservation?

Yes, there are ongoing research projects at various particle accelerators and laboratories around the world, such as the Large Hadron Collider at CERN and the Thomas Jefferson National Accelerator Facility. These projects aim to further our understanding of neutral pion decay and spin conservation, as well as other related topics in particle physics.

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