Randall-Sundrum with Kalb-Ramond field: return of the hierarchy problem?
  We show that when the antisymmetric Kalb-Ramond field is included in the Randall-Sundrum scenario, although the hierarchy problem can be solved, it requires an extreme fine tuning of the Kalb-Ramond field (about 1 part in $10^{62}$). We interpret this as the return of the problem in disguise. Further, we show that the Kalb-Ramond field induces a small negative cosmological constant on the visible brane. 
Saurya Das (U of Lethbridge), Anindya Dey (HRI, Allahabad), Soumitra   SenGupta (IACS, Kolkata)