Beta plus and Beta minus decay

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Discussion Overview

The discussion centers around the interpretation of Feynman diagrams in the context of beta plus and beta minus decay, specifically focusing on the direction of arrows representing particles and antiparticles. Participants explore the implications of these conventions and their relationship to time in particle physics.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant expresses confusion about why the positron in Feynman diagrams points towards the W+ boson during beta minus decay, questioning the directionality of particles and antiparticles.
  • Another participant explains that the arrows in Feynman diagrams are a convention to differentiate between particles and antiparticles, noting that antiparticles are sometimes mathematically treated as particles moving backwards in time.
  • A participant seeks clarification on the concept of "particles going back in time," requesting further explanation or resources.
  • It is mentioned that Feynman diagrams are sketched on a space-time axis, which can lead to the interpretation of arrows indicating motion backwards in time.
  • One participant questions the validity of the idea that particles can go back in time, seeking confirmation of this concept.
  • Another participant asserts that particles do not actually go back in time, emphasizing that all particles move forward in time according to reasonable definitions.
  • A further explanation is provided regarding the convention of antiparticles moving backwards in time, linking it to issues in relativistic quantum mechanics and the visualization of negative energy solutions.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of time in relation to particle behavior, with some supporting the mathematical convention of antiparticles moving backwards in time while others clarify that this is not a literal representation of physical behavior.

Contextual Notes

The discussion highlights limitations in understanding the implications of Feynman diagrams and the conventions used in particle physics, particularly regarding the treatment of time and energy in relativistic contexts.

Dmitry2017
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Hi i can't understand why is the positron in Feynmans diagram is going towards the w+ boson and not outward, i have a problem understanding why this is happining for beta minus decay also the antielectron neutrino is also going towards the reaction of the w- boson
 
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In both cases, the particles are emitted. The arrows on the lines are just a convention to distinguish between particles and antiparticles in Feynman diagrams.
While those antiparticles have some mathematical similarity to "particles going backwards in time", this is just a mathematical thing.
 
Thank you but what do you mean "particles going back in time" can you either explain or send a link thanks again
 
The feynmann diagrams are generally sketched on space+time axis- so the arrows can show mltion backwards in time
 
So particles can go back in time? is this proven ?
 
No, particles do not go back in time. This is just a way to express how mathematical solutions look like. All particles go forward in time (for any reasonable definition of what that means).
 
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It is just a convention to say that antiparticles move backwards in time, due to some "problems" arising when you try to deal with relativistic quantum mechanics- free solutions with negative energy.
The interpretations over that feature vary and are somewhat equivalent, but the most easy to see is that you can put the minus of energy into the t variable, so you'll get backwards in time moving particles (corresponding to antiparticles). Of course it's just a visualization, and not something that must be taken literally.
 
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