The effect of S-wave interference on the $B^0 \to K^{\ast 0}\ell^+\ell^-$ angular observables

Understand

The rare decay $B^0 \to K^{\ast 0}\ell^+\ell^-$ is a flavour changing neutral current decay with a high sensitivity to physics beyond the Standard Model.

• Nearly all theoretical predictions and all experimental measurements so far have assumed a $K^{\ast 0}$ P-wave that decays into the $K^+\pi^-$ final state.
• In this paper the addition of an S-wave within the $K^+\pi^-$ system of $B^0 \to K^{\ast 0}\ell^+\ell^-$ and the subsequent impact of this on the angular distribution of the final state particles is explored.
• The inclusion of the S-wave causes a distinction between the values of the angular observables obtained from counting experiments and those obtained from fits to the angular distribution.