Quantum effects in $QED_{3+1}$ with an extra compactified dimension
  We evaluate one-loop effects for $QED_{3+1}$ in the presence of an extra compactified dimension, in a non-trivial vacuum for the gauge field, such that a non-vanishing magnetic flux is encircled along the extra dimension. We obtain the vacuum polarization tensor and evaluate the exact parity breaking term. 
C. Ccapa Ttira (1), C. D.Fosco (1), A. P. C. Malbouisson (2) and I.   Roditi (2) ((1) Centro At\'omico Bariloche and Institu...