how virtual are the real particles?

Alejandro Rivero

Consider a non interacting field, and a one particle excitation there.
We calculate the propagator using path integral, and to do this we add
all the trajectories; most of them of course violate classical
mechanics preservation laws and they are weighted down. Well, usual
business.

Now, I wonder, can we tell that in some sense the trajectories we are
contemplating are off-shell? And if so, can we tell that particle
propagation is always "virtual"?

Alejandro

FrediFizzx

"Alejandro Rivero" <Al.Rivero@gmail.com> wrote in message
news:ab741577.0504190725.2fd7e1c8@posting.google.com...
| Consider a non interacting field, and a one particle excitation there.
| We calculate the propagator using path integral, and to do this we add
| all the trajectories; most of them of course violate classical
| mechanics preservation laws and they are weighted down. Well, usual
| business.
|
| Now, I wonder, can we tell that in some sense the trajectories we are
| contemplating are off-shell? And if so, can we tell that particle
| propagation is always "virtual"?

I think in the current interpretation a "real" particle has no
"virtualness" when "non-interacting". But I think we have to consider
that there is really no such thing as a "particle field" or even field
that is non-interacting. IOW, it is impossible to have a "bare"
fermion. So maybe the first part of your statement; "Consider a non
interacting field..." is not possible to consider really. What would be
an example of a real physical non-interacting field? This seems to be
very abstract to me.

FrediFizzx