How long can a virtual particles exist in a vacuum state?

[mitrasoumya]

As much as I have understood, virtual particles keep appearing and disappearing in a vacuum state. This leads to zero-point energy, Casimir effect etc. Now, I want to know if there is a lifetime (i.e. a time limit) for which these virtual particles can exist before disappearing. Also can there be a mechanism by which they can be made to stay longer?

 

[A. Neumaier]

I want to know if there is a lifetime (i.e. a time limit) for which these virtual particles can exist before disappearing.

No. Virtual particles have no life and hence no lifetime. See https://www.physicsforums.com/insights/misconceptions-virtual-particles/