Understanding the penguin amplitude in $B \to φK$ decays

We calculate the branching ratios for pure penguin decay modes, the $B\to \phi K$ decays using perturbative QCD approach. Our results of branching ratios are consistent with the experimental data and larger than those obtained from the naive factorization assumption and the QCD-improved factorization approach. This is due to the penguin enhancement in perturbative QCD approach.