Question about Feynman diagram showing annihilation

[songoku]

Homework Statement

Please see below

Relevant Equations

Feynman Diagram

This is Feynman diagram of annihilation I get from wikipedia
https://en.wikipedia.org/wiki/Annihilation

I don't understand what the middle line with arrow to the right is. If I consider the left vertex and conservation of charge, it means the horizontal line with arrow to the right should carry negative charge. So it is W^-?

Thanks

 

[Orodruin]

It is an electron line.

A W-line would violate both Lorentz symmetry and electroweak gauge symmetry.

 

[songoku]

It is an electron line.

A W-line would violate both Lorentz symmetry and electroweak gauge symmetry.

Can the horizontal line be removed so the diagram only shows two lines (one for electron and one for positron) and two photons?

Thanks

 

[Orodruin]

Can the horizontal line be removed so the diagram only shows two lines (one for electron and one for positron) and two photons?

Thanks

No, absolutely not.

 

[songoku]

No, absolutely not.

Is the reason related to post #2? And maybe also related to conservation of energy and momentum?

Thanks