Despite our excitement, open theoretical questions remain that prevent us from definitively claiming that physics beyond the Standard Model has been observed. The most serious question arises from so-called "charming penguins," a set of processes present in the Standard Model, whose contributions are extremely tricky to predict. Recent estimates of these charming penguins suggest their effects are not large enough to explain our data.

In the diagram of the bottom quark decay, the virtual particles appear as a loop and a series of squiggles. The final drawing—first introduced by Mikhail Shifman, Arkady Vainshtein and Valentin Zakharov—almost resembles a bird with a head, a round, white belly and two feet.