Effects of new physics in the rare decays B → Kl+l− and B → K∗l+l−

We parametrize phenomenologically possible new physics effects and calculate their influence on the invariant dilepton mass spectrum and the Dalitz plot for the decays B → Kl+l− and B → K∗l+l−. Especially the decay into K∗ yields a wealth of new information on the form of the new interactions since the Dalitz plot is sensitive to subtle interference effects. We also show how transversely polarized K∗-mesons give additional information.