The effects of enhanced Z penguins on lepton polarizations in $B \to X_s   \ell^+ \ell^-$
  The sensitivity of the $B \to \pi K$ mode to electroweak penguins and the recent experimental data for the $B \to \pi \pi$, $\pi K$ modes has given rise to what is known as the ``$B \to \pi K$ puzzle''. Recently it has been observed that this {\sl puzzle} can be resolved by considering the new physics which can enter via $Z^0$ penguins. In this note we analyze the effect of this enhanced $Z^0$ penguins on the lepton polarization asymmetries of $b \to s \ell^+ \ell^-$. 
S. Rai Choudhury, A. S. Cornell and Naveen Gaur