  The results of our research on noncommutative perturbative quantum field
theory and its relation to string theory are exposed with details. 1) We give
an introduction to noncommutative quantum field theory and its derivation from
open string theory in an antisymmetric background. 2) We perform a perturbative
Wilson loop calculation for 2D NCYM. We compare the LCG results for the WML and
the PV prescription. With WML the loop is well-defined and regular in the
commutative limit. With PV the result is singular. This is intriguing: in the
commutative theory their difference is related to topological excitations,
moreover PV provides a point-like potential. 3) Commutative 2D YM exhibits an
interplay between geometrical and U(N) gauge properties: in the exact
expression of a Wilson loop with n windings a scaling intertwines n and N. In
the NC case the interplay becomes tighter due to the merging of space-time and
``internal'' symmetries. Surprisingly, in our up to O(g^6) (and beyond) crossed
graphs calculations the scaling we mentioned occurs for large n, N and theta.
4) We discuss the breakdown of perturbative unitarity of noncommutative
electric-type QFT in the light of strings. We consider the analytic structure
of string loop two-point functions suitably continuing them off-shell, and then
study the Seiberg-Witten limit. In this way we pick up how the unphysical
tachyonic branch cut appears in the NC field theory.
