A new CY elliptic fibration and tadpole cancellation
  Tadpole cancellation in Sen limits in F-theory was recently studied by Aluffi and Esole. We extend their results, generalizing the elliptic fibrations they used and obtaining a new case of universal tadpole cancellation, at least numerically. We could not find an actual Sen limit having the correct brane content, and we argue that such a limit may not exist. We also give a uniform description of the fibration used by Aluffi and Esole as well as a new, simple, fibration which has non-Kodaira type fibers. 
Sergio L. Cacciatori, Andrea Cattaneo and Bert Van Geemen
hep-th math-ph math.MP