
#1
Jan1914, 03:56 PM

P: 3

Hi i cant 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




#2
Jan1914, 04:19 PM

Mentor
P: 10,853

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. 



#3
Jan1914, 10:08 PM

P: 3

Thank you but what do you mean "particles going back in time" can you either explain or send a link thanks again




#4
Jan2014, 02:15 AM

P: 378

Beta plus and Beta minus decay
The feynmann diagrams are generally sketched on space+time axis so the arrows can show mltion backwards in time




#5
Jan2014, 05:07 PM

P: 3

So particles can go back in time? is this proven ?




#6
Jan2014, 05:29 PM

Mentor
P: 10,853

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).




#7
Jan2014, 07:43 PM

P: 378

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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