Consider the Feynman diagram below:
in the case of ϕ4 theory where there is no bare mass: L=12∂μϕ∂μϕ−λ4!ϕ4
the contribution of this diagram is given by: I=−iλ2∫ddk(2π)d1k2+iε
typically such integrals are done using Feynman and Schwinger Parameterizations. In this case, however Schwinger parameterization won't work as you will have a completely imaginary exponential. It also appears to be the case that limm→0−iλ2∫ddk(2π)d1k2−m2+iε
which can be done using Schwinger parameterization does not converge onto the same value as I. Thus my question is: what is the most common way to deal with integrals of the form I in QFT ideally using minimal subtraction.
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