Particle Annihilation in Interacting Fields: Frequency and Bound State Quanta

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Discussion Overview

The discussion revolves around the concept of particle annihilation in the context of interacting fields within quantum field theory (QFT). Participants explore the frequency of annihilation events, the nature of bound versus free quanta, and the implications for atomic structures, particularly in relation to carbon atoms and their constituents.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about the frequency of quanta annihilation and whether bound state quanta can undergo annihilation, suggesting a focus on fermion fields.
  • Another participant emphasizes that in QFT, particle propagation involves creation and annihilation events, indicating that such events are common but may not change the total number of particles.
  • There is a discussion about the annihilation of particles in bound states, with a specific example of electron-positron annihilation through positronium, which involves intermediate states before annihilation.
  • Some participants clarify that the term "quanta that make up carbon" is misleading, as particles in a carbon atom interact continuously, and annihilation is a mathematical description rather than a literal vanishing of atoms.
  • Questions arise regarding the implications of particle creation and annihilation in many-particle systems, particularly whether this applies to all particles or just those not forming part of stable structures like carbon atoms.
  • A reference is made to the historical context of bound states in quantum electrodynamics, specifically mentioning positronium and its role in hyperfine splitting.

Areas of Agreement / Disagreement

Participants express differing views on the nature of quanta in bound states and the implications of annihilation events. There is no consensus on whether bound state quanta can be annihilated or how this affects atomic structures.

Contextual Notes

Participants highlight limitations in understanding the mathematical tools of QFT and the distinction between real particles and virtual interactions. The discussion reflects uncertainty regarding the implications of annihilation for atomic stability and structure.

I2004
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I need some advice. I have read that interacting fields can lead to quanta annihilation? How often does this happen, and can bound state quanta annihilate or is it just free quanta?

Thanks
 
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Quanta of what?
 
K^2 said:
Quanta of what?

quanta of a fermion field. Can bound quanta of a fermion field be annihilated or is it just unbound quanta that can get annihilated.how common is particle annihilation in quantum field theory
 
In QFT, the very propagation of particles is described with creation-annihilation events. So I'd say common. :) But that's a little different, since either number of particles doesn't change, or virtual particles are involved.

As far as particle-anti-particle annihilation, it actually tends to happen from bound state. Consider ep annihilation. It usually takes place via intermediate state of positronium, which will usually collapse to ground state first, and only then annihilate. That's what gives you the zero angular momentum condition on the emitted photons.
 
IM proberly not getting my point across. The quanta that make up carbon are all in a bound state, can these quantum get annihilated, and if they do and it happens often, does this lead to atoms changing form?
 
There are no "quanta that make up carbon".
Particles in a carbon atom interact with each other and their environment all the time, quantum field theory describes those interaction with creation and annihilation operators. This is a mathematical tool. It is not like a carbon atom would vanish somehow (unless you shoot antiparticles on it).
 
mfb said:
There are no "quanta that make up carbon".
Particles in a carbon atom interact with each other and their environment all the time, quantum field theory describes those interaction with creation and annihilation operators. This is a mathematical tool. It is not like a carbon atom would vanish somehow (unless you shoot antiparticles on it).

what does this mean? when the carbon atom interacts with itself and other atoms, parts of it/all of it are created and annihilated?
 
I think you ran into some misconception about QFT here.
In QFT, particles are created and annihilated all the time - but they are not like billard balls, it is just a description of their interaction. The total number of real electrons and valence quarks (the quarks which define the type of nucleus -> proton vs. neutron) is constant.
 
mfb said:
I think you ran into some misconception about QFT here.
In QFT, particles are created and annihilated all the time - but they are not like billard balls, it is just a description of their interaction. The total number of real electrons and valence quarks (the quarks which define the type of nucleus -> proton vs. neutron) is constant.
what does that mean in terms of many particle systems? as they are made of particles, are the parts of these systems always being created and annihilated or is it just single particles that are annihilated? the ones not making up a carbon atom for example
 
  • #10
A familiar example of bound state comes from quantum electrodynamics in which a hydrogen like thing called positronium which consists of electron and positron can go for a two photon annihilation.It contributes a big part in hyperfine splitting of it.The original method for treating such bound states were developed by karplus and klein.
 
  • #11
as they are made of particles
And all those particles behave like all other particles. This should answer your question.

Do not send me PMs please, I can see your reply in the subscribed threads.
 

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