$q=u,d,s,c,b$, are referred to as QCD penguin operators, and $$\begin{aligned}
\label{EWp}
   Q_7 &=& \frac32\,(\bar b_\alpha s_\alpha)_{V-A}\,\sum_q\,e_q\,
    (\bar q_\beta q_\beta)_{V+A} \,, \nonumber\\
   Q_8 &=& \frac32\,(\bar b_\alpha s_\beta)_{V-A}\,\sum_q\,e_q\,
    (\bar q_\beta q_\alpha)_{V+A} \,, \nonumber\\
   Q_9 &=& \frac32\,(\bar b_\alpha s_\alpha)_{V-A}\,\sum_q\,e_q\,
    (\bar q_\beta q_\beta)_{V-A} \,, \nonumber\\
   Q_{10} &=& \frac32\,(\bar b_\alpha s_\beta)_{V-A}\,\sum_q\,e_q\,
    (\bar q_\beta q_\alpha)_{V-A} \,,\end{aligned}$$ with $e_q$ denoting the electric charges of the quarks, are called electroweak penguin operators. The notation $(\bar q_1 q_2)_{V\pm A}$ implies $\bar q_1\gamma^\mu
(1\pm\gamma_5)q_2$. The terminology of QCD and electroweak penguins is slightly misleading insofar as the Wilson coefficients of the QCD penguin operators also receive small contributions from electroweak penguin and box diagrams. However, in the SM there are no strong-interaction contributions to the coefficients of the electroweak penguin operators. The operator $Q_{8g}
=\frac{g_s m_b}{8\pi^2}\,\bar b\,\sigma^{\mu\nu}(1-\gamma_5)
G_{\mu\nu}s$ in (\[Heff\]) is the chromomagnetic dipole operator. The analogous electromagnetic dipole operator and semileptonic operators containing products of a quark current with a lepton current can be safely discarded from the effective Hamiltonian for hadronic $B$ decays.

In general, physics beyond the SM can induce a much larger set of penguin operators, and it is therefore unavoidable for our purposes to generalize the standard nomenclature reviewed above. However, for all the models 