Why doesnt neutron scattering violate charge conservation?

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rwooduk
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Two quark-line diagrams in red: left, a proton (u d u) and neutron (u d d) exchanging a pi-minus formed from d and u-bar quarks via gluon lines; right, a simple vertex diagram with incoming p and n, dashed pi- exchange line, outgoing n and p.


p + n -> p + n + ∏^-

check charge conservation:

+ 1 + 0 = +1 + 0 -1

it doesn't equal so it wouldn't be possible? please could someone suggest why this is, or if I'm doing something wrong?

thanks in advance.

edit is it because the pion is the force carrier therefore should not be included in the reaction and check above?
 
No it's because the pion is absorbed on the right hand side and is not part of the final configuration.

You just have p + n -> n + p which conserves charge

Or you can split it into two interactions:

n -> p + [itex]\pi[/itex]- and then p + [itex]\pi[/itex]- -> n

both of which conserve charge
 
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kjhskj75 said:
No it's because the pion is absorbed on the right hand side and is not part of the final configuration.

You just have p + n -> n + p which conserves charge

Or you can split it into two interactions:

n -> p + [itex]\pi[/itex]- and then p + [itex]\pi[/itex]- -> n

both of which conserve charge

explains it perfectly, many thanks!