Re: How real are the "Virtual" partticles?

Arnold Neumaier wrote:
> Eugene Stefanovich wrote:
>
>>
>> Arnold Neumaier wrote:
>>
>>>
>>>> When the S-matrix is calculated,
>>>> we use the Hamiltonian expressed in terms of bare particles
>>>> and we take the initial and final states formed as a^*b^*...|0>
>>>> where a^*, b^*, etc are the same operators of bare particles, and
>>>> |0> is bare vacuum.
>>>
>>>
>>> No. This is only the unrenormalized, meaningless version.
>>> The renormalized, physical version is about the behavior of
>>> physical, dressed states.
>>
>>
>> Why you call this version meaningless?
>
>
> unrenormailzed = meaningless,
> renormalized = physical.
>

I showed you that standard calculation of the S-matrix does not involve
redefinition of particles. Particle creation and annihilation operators
are defined in the beginning and they stay unchanged until the final
calculation of scattering amplitudes. The Hamiltonian is defined
in terms of these particle operators. You can call them "bare"
operators, if you like, but standard approach does not make any
distinction between bare, dressed or physical or "renormalized"
particles.
The renormalization is achieved by adding counterterms to the
Hamiltonian. Correctly chosen counterterms guarantee that
(in the limit of infinite cutoff) all bad terms in the S-matrix
cancel out and we obtain very accurate results.

Standard approach is satisfied with this situation: infinite
counterterms in the Hamiltonian and perfectly accurate S-matrix.
The distinction between bare and dressed particles is important
for those who want to study the time evolution and need a well-defined
Hamiltonian for that. To do that we need dressing.
As I tried to explain a few times the renormalization
and dressing are very different procedures having different goals
and involving different techniques. So, I do not understand what is
your definition of "renormalized particles", and why you say they
are equivalent to "dressed" or "physical" particles.

Eugene Stefanovich.

.

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