1. Validity of Born approximation { If BA applicable |Correction | = (evaluated at r=0) condition for validity of BA Sakurai p386 c.f.1.19

3. The Lipmann Schwinger Equation – operator formalism Bra- ket- notation … independent of representation choice

4. Plane wave states : stationary states Orthonormality and completeness

5. The Lipmann Schwinger Equation – operator formalism ( up to complications coming from singular nature of the inverse operator Solution to (2.1) We will prove a consistent regularisation procedure is

6. In position basis

7. The Green function