I'm little confused about the unitarity and perturbativity constrains which imposed on a potential's parameters, like 2HD potential.
First, what is most essential ? I mean if unitarity constraind $\lambda$ to say less than 20 and as it's well known perturbativity constraind $\lambda$ to < 4 pi, so what's the most restricted value for $\lambda$ ?
I think being the coupling perturbative is essential so that the theory be finite at higher order correction , so the coupling value in general can't exceed 4 pi .. is it right ?
Hi,
I thought perturbation should be applied on any coupling, even Like Yukawa coupling. About unitarity tell now I don't know much about..
But in general I were talking about 2HD potential, see for example [arXiv:1507.03618v3[hep-ph]] and SM theory pluse colored doublet scalar, see [arXiv:1303.2426v2[hep-ph]], subsection (III, A)..
Example: QED has unitarity problem for vacuum Fmu,ny 2 mean, though it's not seen from initial Lagrangian. It looks like this is not perturbative effect.
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