B Is CP Symmetry Violation the Key to Explaining Matter-Antimatter Imbalance?

AI Thread Summary
The discussion centers on the relationship between CP symmetry violation and the matter-antimatter imbalance in the universe. It highlights the phenomenon of muon neutrinos transforming into electron flavors more frequently than the reverse process, suggesting potential CP violation. The conversation also questions whether pair production and annihilation are time-reversed processes, emphasizing the role of conservation of momentum. Participants debate the implications of these processes and their relevance to understanding the universe's composition. Ultimately, the discourse reflects on the complexities of symmetry violations in particle physics.
Clever Penguin
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Consider a photon undergoing pair production and turn into a particle-antiparticle pair.

Now play this in reverse, you got a particle and an antiparticle colliding to create a single photon. But in annihilation, the result is two or more photons. Violation of T symmetry?

There also seems to be evidence of CP symmetry violation: '[There have been] 32 sightings of muon neutrinos morphing into the electron flavour, compared with just 4 muon antineutrinos becoming the anti-electron variety.'

Source: (https://www.newscientist.com/articl...at-why-antimatter-didnt-blow-up-the-universe/)

Although the above observations have only reached 2 sigma, many believe that this could be the reason why there is more matter than antimatter in the universe. In order for there to be more matter than antimatter in the universe, there has to be a process that violates CP symmetry, so why is this surprising?
 
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Clever Penguin said:
Violation of T symmetry?

No. Why do you think it is? In particular, why do you think pair production in the presence of material is the time-reversed process of annihilation in the vacuum?
 
Clever Penguin said:
Consider a photon undergoing pair production and turn into a particle-antiparticle pair.
This never happens due to conservation of momentum. There is always either another photon or a massive particle involved.
 
Vanadium 50 said:
No. Why do you think it is? In particular, why do you think pair production in the presence of material is the time-reversed process of annihilation in the vacuum?
Because they are the opposite process to each other. Like integration and differentiation. If I was to integrate 'backwards' it would be differentiation. :smile:
Dale said:
This never happens due to conservation of momentum. There is always either another photon or a massive particle involved.
I see. :smile:
 
Clever Penguin said:
Because they are the opposite process to each other.

Why do you think they are? Let me repeat, with emphasis:

"why do you think pair production in the presence of material is the time-reversed process of annihilation in the vacuum?"
 
Vanadium 50 said:
Why do you think they are? Let me repeat, with emphasis:

"why do you think pair production in the presence of material is the time-reversed process of annihilation in the vacuum?"

I see they are not... ?:)
 

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