Introduction to a field-theoretical treatment of neutrino oscillations

We discuss the main features of the field-theoretical approach to neutrino oscillations where one combines neutrino production and detection processes in a single Feynman graph. The 'oscillating neutrinos' are represented by inner lines of this graph and appear in the calculation of the cross sectio n of the total process as propagators of the neutrino mass ei,eigenfields. We show that this field-theoretical approach leads to a transparent treatme nt of neutrino oscillations without ambiguities and provides the correct an swer in cases where the standard approach fails.