Why Do Matter-Antimatter Pairs Annihilate Instead of Sticking Together?

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Discussion Overview

The discussion centers around the behavior of matter-antimatter pairs, specifically why they tend to annihilate each other rather than forming stable structures, akin to how ordinary matter interacts. The scope includes theoretical considerations and examples from particle physics.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant questions why matter-antimatter pairs annihilate instead of "sticking" together like ordinary matter with opposite charges.
  • Another participant points out that matter-antimatter pairs, such as electrons and positrons, can form a bound state called positronium, which can exist for a limited time before annihilation.
  • A third participant mentions that a relativistic positron can annihilate with an atomic electron, providing a specific probability for this interaction based on energy levels.
  • A later reply expresses gratitude for the feedback received in the discussion.

Areas of Agreement / Disagreement

Participants present differing viewpoints on the behavior of matter-antimatter pairs, with some highlighting the possibility of temporary bound states while others focus on the conditions under which annihilation occurs. The discussion remains unresolved regarding the primary reasons for annihilation versus binding.

Contextual Notes

Some assumptions about the conditions necessary for annihilation versus binding are not fully explored, and the discussion does not clarify the implications of the probabilities mentioned.

quantumkiko
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Why does an matter-antimatter pair annihilate each other instead of "sticking" together (i.e. like ordinary matter with opposite charges do)?
 
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In fact, they don't always annihilate right away. For example, an electron and a positron may form a bound state called positronium. Positronium doesn't live forever, but a certain form of it can live for a relatively long amount of time, more than 100 nanoseconds! That may not sound like much, but it does show that matter and anti matter don't have to immediately annihilate.

http://prl.aps.org/abstract/PRL/v90/i20/e203402
http://physicsworld.com/cws/article/news/17559
http://en.wikipedia.org/wiki/Positronium

Hope this helps.
 
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A relativistic positron can annihilate in flight with an atomic electron in matter. The integrated probability for a 50-MeV stopping positron is ~ 15%. See pages 384-6 in Heitler "The Quantum Theory of Radiation" Fourth Edition.
Bob S
 
Thank you very much for the feedbacks! I appreciate it. =)
 

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