A bstract The invariance of physical observables under redefinitions of the quantum fields is
a well-known and important property of quantum field theory. We study perturbative field …

A bstract Perturbiner expansion provides a generating function for all Berends-Giele
currents in a given quantum field theory. We apply this method to various effective field …

A bstract I present a novel Four-Dimensional Regularization/Renormalization approach
(FDR) to ultraviolet divergences in field theories which can be interpreted as a natural …

A bstract Effective Field Theory calculations used in countless phenomenological analyses
employ dimensional regularization, and at intermediate stages of computations, the operator …

This chapter reviews the formalism of renormalization in quantum field theories with special
regard to effective quantum field theories. It is well known that quantum field theories are …

A bstract While the notion of open quantum systems is itself old, most of the existing studies
deal with quantum mechanical systems rather than quantum field theories. After a brief …

This chapter compiles an introductory set of lectures on the basic ideas and methods of
effective field theories (EFTs). Other lectures in this book go into more detail about the most …

A bstract We present a new method for renormalisation group improvement of the effective
potential of a quantum field theory with an arbitrary number of scalar fields. The method …

A bstract We find a general formula for the two-loop renormalization counterterms of a scalar
quantum field theory with interactions containing up to two derivatives, extending't Hooft's …

We investigate the high-order behavior of perturbative matching conditions in effective field
theories. These series are typically badly divergent, and are not Borel summable due to …