Measurement of the Decays $\mathit{B}\to \mathit{\phi }\mathit{K}$ and $B\to \phi {\mathit{K}}^{*}$

We have observed the decays $B\to \phi K$ and $\phi K^{*}$ in a sample of over 45 million $B$ mesons collected with the BABAR detector at the PEP-II collider. The measured branching fractions are $B(B^{+}\to \phi K^{+})=({7.7}_{-1.4\mathrm{}}^{+1.6\mathrm{}}\pm 0.8)\times {10}^{-6\mathrm{}}$, $B(B^0\to \phi K^0)=({8.1}_{-2.5\mathrm{}}^{+3.1\mathrm{}}\pm 0.8)\times {10}^{-6\mathrm{}}$, $B(B^{+}\to \phi K^{*+})=({9.7}_{-3.4\mathrm{}}^{+4.2\mathrm{}}\pm 1.7)\times {10}^{-6\mathrm{}}$, and $B(B^0\to \phi K^{*0\mathrm{}})=({8.7}_{-2.1\mathrm{}}^{+2.5\mathrm{}}\pm 1.1)\times {10}^{-6\mathrm{}}$. We also report the upper limit $B(B^{+}\to \phi {\pi }^{+})<1.4\mathrm{}\times {10}^{-6\mathrm{}}$ ( $90\%$ C.L.).