  If the very rare $B_d^0 \to \mu^+\mu^-$ decay is enhanced to (3--4) $\times
10^{-10}$ level or higher, it can be discovered with existing 2011-2012 LHC
data. It might then cast some doubt on the Higgs boson nature of the 126 GeV
boson, since the likely explanation would be due to the fourth generation
$t^\prime$ quark. There is a mild motivation from the known tension in
$\sin2\beta/\phi_1$. If discovery is made before the 13 TeV run, then the $b
\to d$ quadrangle (modulo $m_{t'}$) would suddenly fall into our lap. Continued
pursuit in future runs can probe below $3 \times 10^{-10}$.
